PI Manufacturing AC generators User Manual

Installation, Service & Maintenance

Manual

AC generators with the following for prefixes:

UCI; UCM; UCD 224 & 274 .

SAFETY PRECAUTIONS

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Before operating the generating set, read the generating
set operation manual and this generator manual and
become familiar with it and the equipment.

SAFE AND EFFICIENT OPERATION
CAN ONLY BE ACHIEVED IF THE
EQUIPMENT IS CORRECTLY
OPERATED AND MAINTAINED.

Many accidents occur because of failure to follow
fundamental rules and precautions.

ELECTRICAL SHOCK CAN CAUSE
SEVERE PERSONAL INJURY OR
DEATH.

Observe all WARNING/CAUTION notices.

• Ensure installation meets all applicable safety and
local electrical codes. Have all installations
performed by a qualified electrician.

• Do not operate the generator with protective covers,
access covers or terminal box covers removed.

• Disable engine starting circuits before carrying out
maintenance.

• Disable closing circuits and/or place warning notices
on any circuit breakers normally used for connection
to the mains or other generators, to avoid accidental
closure.

Observe all IMPORTANT, CAUTION, WARNING, and
DANGER notices, defined as:

Important ! Important refers to hazard or unsafe

method or practice which can result in
product damage or related equipment
damage.

Caution refers to hazard or unsafe

Caution !

Warnin

Danger !

Due to our policy of continuous improvement, details in this manual which
were correct at time of printing, may now be due for amendment.
Information included must therefore not be regarded as binding.

Front Cover Photograph

This photograph is representative only. Several variations are available
within the range of generators covered by this manual.

method or p ractice w hi ch can resul t
in product damage or personal
injury.

Warning refers to a hazard or unsafe
method or practice which CAN result
in severe personal injury or possible
death.

!

Danger refers to immediate hazards
which WILL result in severe personal
injury or death.

FOREWORD

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The function of this book is to provide the user of the
Stamford generator with an understanding of the
principles of operation, the criteria for which the generator
has been designed, and the installation and maintenance
procedures. Specific areas where the lack of care or use
of incorrect procedures could lead to equipment damage
and/or personal injury are highlighted, with WARNING
and/or CAUTION notes, and it is important that the
contents of this book are read and understood before
proceeding to fit or use the generator.

STAMFORD Service, Sales and Technical staff of are
always ready to assist and reference to the company for
advice is welcomed.

Incorrect installation, operation,
servicing or replacement of parts can
result in severe personal injury or
death, and/or equipment damage.
Service personnel must be qualified

Warnin

EC DECLARATION OF INCORPORATION

All Stamford generators are supplied with a declaration of
incorporation for the relevant EC legislation, typically in
the form of a label as below.

!

to perform electrical and mechanical
service.

ELECTROMAGNETIC COMPATIBILITY

Additional Information
European Union

Council Directive 89/336/EEC

For installations within the European Union, electrical
products must meet the requirements of the above
directive, and STAMFORD ac generators are supplied on
the basis that:

• They are to be used for power-generation or related
function.

• They are to be applied in one of the following
environments:

Portable (open construction - temporary site supply)
Portable (enclosed - temporary site supply)
Containerised (temporary or permanent site supply)
Ship-borne below decks (marine auxiliary power)
Commercial vehicle (road transport / refrigeration
etc) Rail transport (auxiliar y power)
Industrial vehicle (earthmoving, cranes etc)
Fixed installation (industrial - factory / process plant)
Fixed installation (residential, commercial and light
industrial - home / office / health)
Energy management (Combined heat and power
and/or peak lopping)
Alternative energy schemes

• The standard generators are designed to meet the
‘industrial’ emissions and immunity standards.
Where the generator is required to meet the
residential, commercial and light industrial emissions
and immunity standards reference should be made
to document reference N4/X/011, as additional
equipment may be required.

• The installation earth ing scheme involves c onnection
of the generator frame to the site protective earth
conductor using a minimum practical lead length.

• Maintenance and servicing with anything other than
factory supplied genuine STAMFORD parts will
invalidate warranty and our liability for EMC
compliance.

• Installation, maintenance and servicing is carried out
by adequately trained personnel fully aware of the
requirements of the relevant EC directives

.

Under the EC Machinery Directive section 1.7.4. It is the
responsibility of the generator set builder to ensure the
generator identity is clearly displayed on the front cover
of this book.

CONTENTS

SAFETY PRECAUTIONS
FOREWORD 1
CONTENTS 2&3
SECTION 1 INTRODUCTION 4

1.1 INTRODUCTION 4

1.2 DESIGNATION 4

1.3 SERIAL NUMBER LOCATION
AND IDENTITY NUMBER LOCATION 4

1.4 RATING PLATE AND CE MARKING 4

SECTION 2 PRINCIPLE OF OPERATION 5

2.1 SELF-EXCITED AVR CONTROLLED GENERATORS 5

2.2 PERMANENT MAGNET GENERATOR (PMG) EXCITED ­ AVR CONTROLLED GENERATORS 5

2.3 AVR ACCESSORIES 5

2.4 TRANSFORMER CONTROLLED GENERATORS 5

SECTION 3 APPLICATION OF THE GENERATOR 6
SECTION 4 INSTALLATION - PART 1 8

4.1 LIFTING 8

4.2 ASSEMBLY 8

4.2.1 NO FOOT OPTION 8

4.2.2 TWO BEARING GENERATORS 9

4.2.3 SINGLE BEARING GENERATORS 9

4.3 EARTHING 9

4.4 PRE-RUNNING CHECKS 9

4.4.1 INSULATION CHECK 9

4.4.2 DIRECTION OF ROTATION 10

4.4.3 VOLTAGE AND FREQUENCY 10

4.4.4 AVR SETTINGS 10

4.4.4.1 TYPE SX460 AVR 10

4.4.4.2 TYPE SX440 AVR 10

4.4.4.3 TYPE SX421 AVR 11

4.4.4.4 TYPE MX341 AVR 11

4.4.4.5 TYPE MX321 AVR 11

4.4.5 TRANSFORMER CONTROLLED
EXCITATION SYSTEM (Series 5) 12

4.5 GENERATOR SET TESTING 12

4.5.1 TEST METERING/C AB LING 12

4.6 INITIAL START-UP 12

4.7 LOAD TESTING 13

4.7.1 AVR CONTROLLED GENERATORS - AVR ADJUSTMENTS 13

4.7.1.1 UFRO (Under Frequency Roll Off)
(AVR Types SX460, SX440, SX421, MX341 and MX321) 13

4.7.1.2 EXC TRIP (Excitation Trip) 14

4.7.1.3 OVER/V (Over Voltage) 14

4.7.1.4 TRANSIENT LOAD SWITCHING ADJUSTMENTS 14

4.7.1.5 RAMP BUILD UP TIME 15

4.7.2 TRANSFORMER CONTROLLED GENERATORS ­ TRANSFORMER ADJUSTMENT 15

4.8 ACCESSORIES 15

SECTION 5 INSTALLATION - PART 2 16

5.1 GENERAL 16

5.2 GLANDING 16

5.3 EARTHING 16

5.4 PROTECTION 16

5.5 COMMISSIONING 16

CONTENTS

SECTION 6 ACCESSORIES 17

6.1 REMOTE VOLTAGE ADJUST (ALL AVR TYPES) 17

6.2 PARALLEL OPERATION 17

6.2.1 DROOP 17

6.2.1.1 SETTING PROCEDURE 18

6.2.2 ASTATIC CONTROL 18

6.3 MANUAL VOLTAGE REGULATOR (MVR) ­ MX341 and MX321 AVR 18

6.4 OVERVOLTAGE DE-EXCITATION BREAKER
SX421 and MX321 AVR 18

6.4.1 RESETTING THE BREAKER 19

6.5 CURRENT LIMIT - MX321 AVR 19

6.5.1 SETTING PROCEDURE 19

6.6 POWER FACTOR CONTROLLER (PFC3) 20

SECTION 7 SERVICE AND MAINTENANCE 21

7.1 WINDING CONDITION 21

7.1.1 WINDING CONDITION ASSESSMENT 21

7.1.2 METHODS OF DRYING OUT GENE RATORS 21

7.2 BEARINGS 23

7.3 AIR FILTERS 23

7.3.1 CLEANING PROCEDURE 23

7.4 FAULT FINDING 23

7.4.1 SX460 AVR - FAULT FINDING 23

7.4.2 SX440 AVR - FAULT FINDING 24

7.4.3 SX421 AVR - FAULT FINDING 24

7.4.4 TRANSFORMER CONTROL - FAULT FINDING 24

7.4.5 MX341 AVR - FAULT FINDING 25

7.4.6 MX321 AVR - FAULT FINDING 25

7.4.7 RESIDUAL VOLTAGE CHECK 26

7.5 SEPARATE EXCITATION TEST PROCEDURE 26

7.5.1 GENERATOR WINDINGS, ROTATING DIODES and
PERMANENT MAGNET GENERATOR (PMG) 26

7.5.1.1 BALANCED MAIN TERMINAL VOLTAGES 26

7.5.1.2 UNBALANCED MAIN TERMINAL VOLTAGES 27

7.5.2 EXCITATION CONTROL TEST 27

7.5.2.1 AVR FUNCTION TEST 27

7.5.2.2 RANSFORMER CONTROL 28

7.5.3 REMOVAL AND REPLACEMENT OF COMPONENT
ASSEMBLIES 28

7.5.3.1 REMOVAL OF PERMANENT MAGNET GENERATOR (PMG) 28

7.5.3.2 REMOVAL OF BEARINGS 28

7.5.3.3 REMOVAL OF ENDBRACKET AND EXCITER STATOR 28

7.5.3.4 REMOVAL OF THE ROTOR ASSEMBLY 29

7.6 RETURNING TO SERVICE 29

SECTION 8 SPARES AND AFTER SALES SERVICE 30

8.1 RECOMMENDED SPARES 30

8.2 AFTER SALES SERVICE 30

SECTION 9 PARTS IDENTIFICATION 32

TYPICAL SINGLE BEARING GENERATOR (Fig. 11) 33
TYPICAL TWO BEARING GENERATOR (Fig. 12) 35
TYPICAL TWO BEARING (SERIES 5) GENERATOR (Fig. 13) 37
ROTATING RECTIFIER ASSEMBLY (Fig. 14) 38

SECTION 1

INTRODUCTION

1.1 INTRODUCTION

The UC22/27 range of generators is of brushless rotating field
design, available up to 660V/50Hz (1500 rpm) or 60Hz (1800
rpm), and built to meet BS5000 Part 3 and international
standards.
All the UC22/27 range are self-excited with excitation power
derived from the main output windings, using either the
SX460/SX440/SX421 AVR. The UC22 is also available with
specific windings and a transformer controlled excitation
system.

A permanent magnet generator (PMG) powered excitation
system is available as an option using either the MX341 or
MX321 AVR.

Detailed specification sheets are available on request.

1.2 DESIGNATION

1.3 SERIAL NUMBER LOCATION AND IDENTITY
NUMBER LOCATION

Each generator is metal stamped with it’s own unique serial
number, the location of this number is described below.

UCI and UCM generators have their serial number stamped
into the upper section of the drive end frame to end bracket
adaptor ring, shown as item 31 in the parts lists at the back of
this book.

UCD generators have their serial number stamped into the
top of the drive end adaptor /fan shroud casting. If for any
reason this casting is removed, it is imperative that care is
taken to refit it to the correct generator to ensure correct
identification is retained.

Inside the terminal box two adhesive rectangular labels have
been fixed, each carrying the generators unique identity
number. One label has been fixed to the inside of the terminal
box sheet metal work, and the second label fixed to the main
frame of the generator.

1.4 RATING PLATE

The generator has been supplied with a self adhesive rating
plate label to enable fitting after final assembly and painting.

It is intended that this label will be stuck to the outside of the
terminal box on the left hand side when viewed from the
N.D.E. To assist with squarely positioning the label, location
protrusions have been made in the sheet metalwork.

A CE Mark label is also supplied loose for fitment after f inal
assembly and painting. This should be attached to an external
surface of the Generator at a suitable location where it will not
be obscured by the customer's wiring or other fittings.

The surface in the area where a label is to be stuck must be
flat, clean, and any paint finish be fully dry before attempting
to attach label. Recommended method for attaching label is
peel and fold back sufficient of the backing paper to expose
some 20 mm of label adhesive along the edge which is to be
located against the sheet metal protrusions. Once this first
section of label has been carefully located and stuck into
position the backing paper can be progressively removed, as
the label is pressed down into position. The adhesive will
achieve a permanent bond in 24 hours.
.

SECTION 2

PRINCIPLE OF OPERATION

2.1 SELF-EXCITED AVR CONTROLLED

The main stator provides power for excitation of the exciter
field via the SX460 (SX440 or SX421) AVR which is the
controlling device governing the level of excitation provided to
the exciter field. The AVR responds to a voltage sensing
signal derived from the main stator winding. By controlling the
low power of the exciter field, control of the high power
requirement of the main field is achieved through the rectified
output of the exciter armature.

The SX460 or SX440 AVR senses average voltage on two
phases ensuring close regulation. In addition it detects engine
speed and provides voltage fall off with speed, below a pre­selected speed (Hz) setting, preventing over-excitation at low
engine speeds and softening the effect of load switching to
relieve the burden on the engine.

The SX421 AVR in addition to the SX440 features has three
phase rms sensing and also provides for over voltage
protection when used in conjunction with an external circuit
breaker (switchboard mounted).

2.2 PERMANENT MAGNET GENERATOR (PMG)
EXCITED - AVR CONTROLLED GENERATORS

The permanent magnet generator (PMG) provides power for
excitation of the exciter field via the AVR (MX341 or MX321)
which is the controlling device governing the level of excitation
provided to the exciter field. The AVR responds to a voltage
sensing signal derived, via an isolating transformer in the
case of MX321 AVR, from the main stator winding. By
controlling the low power of the exciter field, control of the
high power requirement of the main field is achieved through
the rectified output of the exciter armature.

The PMG system provides a constant source of excitation
power irrespective of main stator loading and provides high
motor starting capability as well as immunity to waveform
distortion on the main stator output created by non linear
loads, e.g. thyristor controlled dc motor.

The MX341 AVR senses average voltage on two phases
ensuring close regulation. In addition it detects engine speed
and provides an adjustable voltage fall off with speed, below a
pre-selected speed (Hz) setting, preventing over-excitation at
low engine speeds and softening the effect of load switching
to relieve the burden on the engine. It also provides over­excitation protection which acts following a time delay, to de­excite the generator in the event of excessive exciter field
voltage.

The MX321 provides the protection and engine relief features
of the MX341 and additionally incorporates 3 phase rms
sensing and over-voltage protection.
The detailed function of all the AVR circuits is covered in the
load testing (subsection 4.7).

2.3 AVR ACCESSORIES

The SX440, SX421, MX341 and MX321 AVRs incorporate
circuits which, when used in conjunction with accessories, can
provide for parallel operation either with 'droop' or 'astatic'
control, VAR/PF control and in the case of the MX321 AVR,
short circuit current limiting.

Function and adjustment of the accessories which can be
fitted inside the generator terminal box are covered in the
accessories section of this book.

Separate instructions are provided with other accessories
available for control panel mounting.

2.4 TRANSFORMER CONTROLLED GENERATORS

The main stator provides power for excitation of the exciter
field via a transformer rectifier unit. The transfo rmer com bines
voltage and current elements derived from the main stator
output to form the basis of an open-loop control system, which
is self regulating in nature. The system inherently
compensates for load current magnitude and power factor
and provides short circuit maintenance in addition to a good
motor starting performance.

Three phase generators normally have a three phase
transformer control for improved performance with
unbalanced loads but a single phase transformer option is
available.

No accessories can be provided with this control system.

SECTION 3

APPLICATION OF THE GENERATOR

The generator is supplied as a component part for installation
in a generating set. It is not, therefore, practicable to fit all the
necessary warning/hazard labels during generator
manufacture. The additional labels required are packaged
with this Manual, together with a drawing identifying their
locations. (See below).

It is the responsibility of the generating set manufacturer to
ensure that the correct labels are fitted, and are clearly visible.

The generators have been designed for use in a maximum
ambient temperature of 40°C and altitude less than 1000m
above sea level in accordance with BS5000.

Ambients in excess of 40°C and altitudes above 1000m can
be tolerated with reduced ratings - refer to the generator
nameplate for rating and ambient. In the event that the
generator is required to operate in an ambient in excess of the
nameplate value or at altitudes in excess of 1000 metres
above sea level, refer to the factory.

The generators are of air-ventilated screen protected drip­proof design and are not suitable for mounting outdoors
unless adequately protected by the use of canopies. Anti­condensation heaters are recommended during storage and
for standby duty to ensure winding insulation is maintained in
good condition.

When installed in a clo sed ca nopy it mu st be en sured t hat t he
ambient temperature of the cooling air to the generator does
not exceed that for which the generator has been rated.

The canopy should be designed such that the engine air
intake to the canopy is separated from the generator intake,
particularly where the radiator cooling fan is required to draw
air into the canopy. In addition the generator air intake to the
canopy should be designed such that the ingress of moisture
is prohibited, preferably by use of a 2 stage filter.

The air intake/outlet must be suitable for the air flow given in
the following table with additional pressure drops less than or
equal to those given below :

Frame

UC22
UCD22
UC27
UCD27

Important ! Reduction in cooling air flow or inadequate

Dynamic balancing of the generator rotor assembly has been
carried out during manufacture in accordance with BS 6861
Part 1 Grade 2.5 to ensure vibration limits of the generator are
in accordance with BS 4999 Part 142.

The main vibration frequencies produced by the component
generator are as follows:- :

4 pole 1500 rpm 25 Hz
1800 rpm 30 Hz

However, vibrations induced by the engine are complex and
contain frequencies of 1.5, 3, 5 or more times the fundamental
frequency of vibration. These induced vibrations can result in
generator vibration levels higher than those derived from the
generator itself. It is the responsibility of the generating set
designer to ensure that the alignment and stiffness of the
bedplate and mountings are such that the vibration limits of
BS5000 Part 3 are not exceeded.

Air Flow
50Hz 60Hz

0.216m³/sec 0.281m³/sec 6mm water gauge
458cfm 595cfm (0.25”)

0.25m³/sec 0.31m³/sec 6mm water gauge
530cfm 657cfm (0.25”)

0.514m³/sec 0.617m³/sec 6mm water gauge
1090cfm 1308cfm (0.25”)

0.58m³/sec 0.69m³/sec 6mm water gauge
1230cfm 1463cfm (0.25”)

protection to the generator can result in
damage and/or failure of windings.

Additional
(intake/outlet)
Pressure Drop

In standby applications where the running time is limited and

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reduced life expectancy is accepted, higher levels than
specified in BS5000 can be tolerated, up to a maximum of
18mm/sec.

Two bearing generators open coupled require a substantial
bedplate with engine/generator mounting pads to ensure a
good base for accurate alignment. Close coupling of engine to
generator can increase the overall rigidity of the set. For the
purposes of establishing set design the bending moment at
the engine flywheel housing to generator adaptor interface
should not exceed 1000ft.lb. (140 kgm). A flexible coupling,
designed to suit the specific engine/generator combination, is
recommended to minimise torsional effects.

Belt driven applications of two bearing gen erators require t he
pulley diameter and design to be such that the side load or
force applied to the shaft is central to the extension and does
not exceed the values given in the table below : -

Frame

UC22 408 4000 110
UC27 510 5000 140

Side Load

kgf N

Shaft

Extension

mm

In instances where shaft extensions greater than specified in
the table have been supplied reference must be made to the
factory for appropriate loadings.

Alignment of single bearing generators is critical and vibration
can occur due to the flexing of the flanges between the engine
and generator. As far as the generator is concerned the
maximum bending moment at this point must not exceed
1000ft.lb. (140kgm). A substanial bedplate with
engine/generator mounting pads is required.

It is expected that the generator will be incorporated into a
generating set operating in an environment, where the
maximum shock load experienced by the generator will not
exceed 3g. in any plane. If shock loads in excess of 3g are to
be encountered, anti-vibration mountings must be
incorporated into the generating set to ensure they absorb the
excess.

The maximum bending moment of the engine flange must be
checked with the engine manufacturer.

Generators can be supplied without a foot, providing the
option for customers own arrangement. See SECTION 4.2.1
for assembly procedure.

Torsional vibrations occur in all engine-driven shaft systems
and may be of a magnitude to cause damage at certain
critical speeds.

It is therefore necessary to consider the torsional vibration
effect on the generator shaft and couplings. It is the
responsibility of the generator set manufacturer to ensure
compatibility, and for this purpose drawings showing the shaft
dimensions and rotor inertias are available for customers to
forward to the engine supplier. In the case of single bearing
generators coupling details are included.

Important ! Torsional incompatibility and/or excessive

vibration levels can cause damage or failure
of generator and/or engine components.

The terminal box is constructed with removable panels for
easy adaptation to suit specific glanding requirements. Within
the terminal box there are insulated terminals for line and
neutral connections and provision for earthing. Additional
earthing points are provided on the generator feet.

The neutral is NOT connected to the frame.
The main stator winding has leads brought out to the

terminals in the terminal box.

No earth connections are made on the
generator and reference to site
regulations for earthing must be made.
Incorrect earthing or protection

Warnin

Fault current curves (decrement curves), together with
generator reactance data, are available on request to assist
the system designer to select circuit breakers, calculate fault
currents and ensure discrimination within the load network.

Warnin

arrangements can result in personal

!

injury or death.

Incorrect installation, service or
replacement of parts can result in severe
personal injury or death, and/or
equipment damage. Service personnel
must be qualified to perform electrical

!

and mechanical service.

SECTION 4

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INSTALLATION - PART 1

4.1 LIFTING

Incorrect lifting or inadequate lifting
capacity can result in severe personal
injury or equipment damage. MINIMUM
LIFTING CAPACITY REQUIRED IS 750Kg.
Generator lifting lugs should NOT be used

Warnin

Two lifting lugs are provided for use with a shackle and pin
type lifting aid. Chains of suitable length and lifting capacity
must be used. Lifting points are designed to be as close to the
centre of gravity of the generator as possible, but due to
design restrictions it is not possible to guarantee that the
generator frame will remain horizontal while lifting. Care is
therefore needed to avoid personal injury or equipment
damage. The correct lifting arrangement is shown on the label
attached to the lifting lug. (See sample below).

Single bearing generators are supplied fitted with a rotor
retaining bar at the non-drive end of the shaft.

To remove retaining bar :

1. Remove the four screws holding the sheet metal cover at
the non drive end and remove cover

2. Remove central bolt holding the retaining bar to the shaft

3. Refit sheet metal cover.

for lifting the complete generator set.

!

Once the bar is removed, to couple the rotor to engine, the
rotor is free to move in the frame, and care is needed during
coupling and alignment to ensure the frame is kept in the
horizontal plane.

Generators fitted with a PMG excitation system are not fitted
with retaining bar. Refer to frame designation to verify
generator type (subsection 1. 2)

4.2 ASSEMBLY

During the assembly of the generator to the engine it will be
necessary firstly to carefully align, then rotate, the combined
generator rotor - engine crankshaft assembly, as part of the
construction process, to allow location, insertion and
tightening of the coupling bolts. This requirement to rotate the
combined assemblies exists for both single and two bearing
units.

During the assembly of single bearing units it is necessary to
align the generator's coupling holes with the engine flywheel
holes; it is suggested that two diametrically opposite location
dowel pins are fitted to the engine flywheel, over which the
generator coupling can slide into final location into the engine
flywheel spigot recess. The dowels must be removed and
replaced by coupling bolts before the final bolt tightening
sequence.

While fitting and tightening the coupling bolts it will be
necessary to rotate the engine crankshaft - generator rotor
assembly. Care should be taken to ensure that rotation is
carried out in an approved manner that ensures safe working
practice when reaching inside the machine to insert or tighten
coupling bolts, and that no component of the assembly is
damaged by nonapproved methods of assembly rotation.

Engine manufacturers have available a proprietary tool or
acility designed to enable manual rotation of the crankshaft
assembly. This must always be used, having been
engineered as an approved method of assembly rotation,
engaging the manually driven pinion with the engine flywheel
starter ring-gear.

Before working inside the generator,

Caution !

during the aligning and fitting of coupling
bolts, care should be taken to lock the
assembly to ensure there is no possibility
of rotational movement.

4.2.1 NO FOOT OPTION

Generators can be supplied without a foot providing the option
for customers own arrangement. For details of mounting this
arrangement, see the general arrangement drawing supplied
with the generator. Alternatively refer to the STAMFORD
factory for a copy of the latest general arrangement drawing
showing the 'NO FOOT OPTION' appropriate to your
generator.

4.2.2 TWO BEARING GENERATORS

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A flexible coupling should be fitted and aligned in accordance
with the coupling manufacturer's instruction. If a close
coupling adaptor is used the alignment of machined faces
must be checked by offering the generator up to the engine.
Shim the generator feet if necessary. Ensure adaptor guards
are fitted after generator/engine assembly is complete. Open
coupled sets require a suitable guard, to be provided by the
set builder. In the case of belt driven generators, ensure
alignment of drive and driven pulleys to avoid axial load on
the bearings. Screw type tensioning devices are
recommended to allow accurate adjustment of belt tension
whilst maintaining pully alignment. Side loads should not
exceed values given in SECTION 3. Belt and pulley guards
must be provided by the set builder.

Important ! Incorrect belt tensioning will result in

excessive bearing wear.
Incorrect guarding and/or generator

Caution !

4.2.3 SINGLE BEARING GENERATORS

Alignment of single bearing generators is critical. If necessary
shim the generator feet to ensure alignment of the machined
surfaces.

For transit and storage purposes the generator frame spigot
and rotor coupling plates have been coated with a rust
preventative.
This MUST BE

A practical method for removal of this coating is to clean the
mating surface areas with a de-greasing agent based on a
petroleum solvent.

Caution !

The sequence of assembly to the engine should generally be
as follows:

1. On the engine check the distance from the coupling
mating face on the flywheel to the flywheel housing
mating face. This should be within +/-0.5mm of nominal
dimension. This is necessary to ensure that a thrust is not
applied to the a.c. generator bearing or engine bearing.

1. Check that the bolts securing the flexible plates to the
coupling hub are tight and locked into position. Torque
tightening is 24.9kgfm (244Nm; 180 lb ft).

2a. UCD224 Only

Torque tightening is 15.29 kgfm (150Nm; 110 lb ft).

1. Remove covers from the drive end of the generator to
gain access to coupling and adaptor bolts.

1. Check that coupling discs are concentric with adaptor
spigot. This can be adjusted by the use of tapered
wooden wedges between the fan and adaptor.
Alternatively the rotor can be suspended by means of a
rope sling through the adaptor opening.

alignment can result in personal injury
and/or equipment damage.

removed before assembly to engine.

Care should be taken not to allow any
cleaning agent to come into prolonged
contact with skin.

1. Offer the a.c. generator to engine and engage both
coupling discs and housing spigots at the same time,
finally pulling home by using the housing and coupling
bolts. Use heavy gauge washers between bolt head and
discs on disc to flywheel bolts.

1. Tighten coupling disc to flywheel. Refer to engine manual
for torque setting of disc to flywheel bolts.

1. Remove wooden wedges.

Caution !

Incorrect guarding and/or generator
alignment can result in personal injury
and/or equipment damage.

4.3 EARTHING

The generator frame should be solidly bonded to the
generating set bedplate. If antivibration mounts are fitted
between the generator frame and its bedplate a suitably rated
earth conductor (normally one half of the cross sectional area
of the main line cables) should bridge across the antivibration
mount.

Warnin

Refer to local regulations to ensure that
the correct earthing procedure has been
followed.

!

4.4 PRE-RUNNING CHECKS

4.4.1 INSULATION CHECK

Before starting the generating set, both after completing
assembly and after installation of the set, test the insulation
resistance of windings. The AVR should be disconnected
during this test. A 500V Megger or similar instrument should
be used. Disconnect any earthing conductor connected
between neutral and earth and megger an output lead
terminal U, V or W to earth. The insulation resistance reading
should be in excess of 5MΩ to earth. Should the insulation
resistance be less than 5MΩ the winding must be dried out as
detailed in the Service and Maintenance section of this
Manual.

Important ! The windings have been H.V. tested durin g

manufacture and further H.V. testing may
degrade the insulation with consequent
reduction in operating life. Should it be
necessary to demonstrate H.V. testing, for
customer acceptance, the tests must be
carried out at reduced voltage levels i.e.
Test Voltage= 0.8 (2 X Rated Voltage + 1000)

4.4.2 DIRECTION OF ROTATION

The generator is supplied to give a phase sequence of U V W
with the generator running clockwise looking at the drive end
(unless otherwise specified at the time of ordering). If the
generator phase rotation has to be reversed after the
generator has been despatched apply to factory for
appropriate wiring diagrams.

UCI224, UCI274, UCM224, UCM274

Machines are fitted with bi-directional fans and are suitable for
running in either direction of rotation.

UCD224, UCD274

Machines are fitted with uni-directional fans and are suitable
for running in one direction only.

4.4.3 VOLTAGE AND FREQUENCY

Check that the voltage and frequency levels required for the
generating set application are as indicated on the generator
nameplate.

Three phase generators normally have a 12 ends out
reconnectable winding. If it is necessary to reconnect the
stator for the voltage required, refer to diagrams in the back of
this manual.

4.4.4 AVR SETTINGS

To make AVR selections and adjustments remove the AVR
cover and refer to 4.4.4.1, 4.4.4.2, 4.4.4.3, 4.4.4.4 or 4.4.4.5
depending upon type of AVR fitted. Reference to the
generator nameplate will indicate AVR type (SX460, SX440,
SX421, MX341 or MX321).

Most of the AVR adjustments are factory set in positions
which will give satisfactory performance during initial running
tests. Subsequent adjustment may be required to achieve
optimum performance of the set under operating conditions.
Refer to 'Load Testing' section for details.

4.4.4.1 TYPE SX460 AVR

The following 'jumper' connections on the AVR should be
checked to ensure they are correctly set for the generating set
application. Refer to Fig. 1 for location of selection links.

1. Frequency selection

50Hz operation LINK C-50
60Hz operation LINK C-60

2. External hand trimmer selection

No external hand trimmer LINK 1-2
External hand trimmer required - REMOVE LINK 1-2 and

connect trimmer across
terminals 1 and 2.

3. AVR Input Selection

High voltage (220/240V) Input NO LINK
Low voltage (110/120V) I nput LINK 3-4

Refer to diagram in the back of this manual to determine
wiring.

4.4.4.2 TYPE AS440 AVR

The following 'jumper' connections on the AVR should be
checked to ensure they are correctly set for the generating set
application.

Refer to Fig. 2 for location of selection links.

1. Frequency selection terminals

50Hz operation LINK C-50
60Hz operation LINK C-60

2. Stability selection terminals

Frame UC22 LINK A-C
Frame UC27 LINK B-C

3. Sensing selection terminals

LINK 2-3
LINK 4-5
LINK 6-7

4. Excitation Interruption Link

LINK K1-K2

4.4.4.4 TYPE MX341 AVR

The following 'jumper' connections on the AVR should be
checked to ensure they are correctly set for the generating set
application.

Refer to Fig. 4 for location of setting links.

1. Frequency selection terminals

50Hz operation LINK 2-3
60Hz operation LINK 1-3

2. Stability selection terminals

Frame UC22 LINK A-C
Frame UC27 LINK B-C

3. Sensing selection terminals *

LINK 2-3
LINK 4-5
LINK 6-7

4. Excitation Interruption Link

LINK K1-K2

4.4.4.5 TYPE MX321 A V R

The following 'jumper' connections on the AVR should be
checked to ensure they are correctly set for the generating set
application.

Refer to Fig. 5 for location of setting links.

Fig. 5

1. Frequency selection terminals

50Hz operation LINK 2-3
60Hz operation LINK 1-3

2. Stability selection terminals

Frame UC22 LINK A-C
Frame UC27 LINK B-C

3. Terminals K1 - K2

Excitation circuit breaker closed.
If this option not fitted, K1 - K2 linked at auxiliary terminal
block.

Fig. 4

4.4.5 TRANSFORMER CONTROLLED EXCITATION

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SYSTEM (Series 5)

This control system is identified with the digit 5 as the last digit
of the frame size quoted on the nameplate.

The excitation control is factory set for the specific voltage
shown on the nameplate and requires no adjustment.

4.5 GENERATOR SET TESTING

During testing it may be necessary to
remove covers to adjust controls exposing
'live' terminals or components. Only
personnel qualified to perform electrical
service should carry out testing and/or

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adjustments.

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4.5.1 TEST METERING/CABLING

Connect any instrument wiring and cabling required for initial
test purposes with permanent or spring-clip type connectors.
Minimum instrumentation for testing should be line - line or
line to neutral voltmeter, Hz meter, load current metering and
kW meter. If reactive load is used a power factor meter is
desirable.

Important ! When fitting power cables for load testing

purposes, ensure cable voltage rating is at
least equal to the genrator rated voltage.
The load cable termination should be placed
on top of the winding lead termination and
clamped with the nut provided.

Check that all wiring terminations for
internal or external wiring are secure, and

Caution !

fit all terminal box covers and guards.
Failure to secure wiring and/or covers may
result in personal injury and/or equipment
failure.

4.6 INITIAL START-UP

During testing it may be necessary to
remove covers to adjust controls exposing
'live' terminals or components. Only
personnel qualified to perform electrical
service should carry out testing and/or

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On completion of generating set assembly and before starting
the generating set ensure that all engine manufacturer's
prerunning procedures have been completed, and that
adjustment of the engine governor is such that the generator
will not be subjected to speeds in excess of 125% of the rated
speed.

Important ! Overspeeding of the generator during initial

In addition remove the AVR access cover (on AVR controlled
generators) and turn VOLTS control fully anti-clockwise. Start
the generating set and run on no-load at nominal frequency.
Slowly turn VOLTS control potentiometer clockwise until rated

adjustments. Refit all access covers after

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adjustments are completed.

setting of the speed governor can result in
damage to the generator rotating
components.

voltage is reached. Refer to Fig. 6a, 6b, 6c, 6d or 6e for
control potentiometer location.

Important ! Do not increase the voltage above the rated

generator voltage shown on the generator
nameplate.

The STABILITY control potentiometer will have been pre-set
and should normally not require adjustment, but should this
be required, usually identified by oscillation of the voltmeter,
refer to Fig. 6a, 6b, 6c, 6d or 6e for control potentiometer
location and proceed as follows :-

1. Run the generating set on no -load and check that speed
is correct and stable

2. Turn the STABILITY control potentiometer clockwise,
then turn slowly anti-clockwise until the generator voltage
starts to become unstable.

The correct setting is slightly clockwise from this position (i.e.
where the machine volts are stable but close to the unstable
region).

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4.7 LOAD TESTING

During testing it may be necessary to
remove covers to adjust controls
exposing 'live' terminals or components.
Only personnel qualified to perform
electrical service should carry out testing

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and/or adjustments. Refit all access

!

covers after adjustments are completed.

4.7.1 AVR CONTROLLED GENERATORS – AVR

ADJUSTMENTS

Refer to Fig. 6a, 6b, 6c, 6d or 6e for control potentiometer
locations.

Having adjusted VOLTS and STABILITY during the initial
startup procedure, other AVR control functions should not
normally need adjustment.

If however, poor voltage regulation on-load or voltage
collapse is experienced, refer to the following paragraphs on
each function to a) check that the symptoms observed do
indicate adjustment is necessary, and b) to make the
adjustment correctly.

4.7.1.1 UFRO (Under Frequency Roll Off) (AVR

Types SX460, SX440, SX421, MX341 and MX321)

The AVR incorporates an underspeed protection circuit which
gives a voltage/speed (Hz) characteristic as shown :

The UFRO control potentiometer sets the "knee point".
Symptoms of incorrect setting are a) the light emitting diode

(LED) indicator, just above the UFRO Control potentiometer,
being permanently lit when the generator is on load, and b)
poor voltage regulation on load, i.e. operation on the sloping
part of the characteristic.

Clockwise adjustment lowers the frequency (speed) setting of
the "knee point" and extinguishes the LED. For Optimum
setting the LED should illuminate as the frequency falls just
below nominal frequency, i.e. 47Hz on a 50Hz generator or
57Hz on a 60Hz generator.

Important ! With AVR Types MX341 and MX321. If the

LED is illuminated and no output voltage is
present, refer to EXC TRIP and/or OVER/V
sections below.

Fig. 7

4.7.1.2 EXC TRIP (Excitation Trip)
AVR Types MX341 and MX321

An AVR supplied from a permanent magnet generator
inherently delivers maximum excitation power on a line to line
or line to neutral short circuit or large overload. In order to
protect the generator windings the AVR incorporates an over
excitation circuit which detects high excitation and removes it
after a pre-determined time, i.e. 8-10 seconds.

Symptoms of incorrect setting are the generator output
collapses on load or small overload, and the LED is
permanently illuminated.

The correct setting is 70 volts +/-5% between terminals X and
XX.

4.7.1.3 OVER/V (Over Voltage)
AVR Type SX421, MX321

Over voltage protection circuitry is included in the AVR to
remove generator excitation in the event of loss of AVR
sensing input.

The MX321 has both internal electronic de-excitation and
provision of a signal to operate an external circuit breaker.

The SX421 only provides a signal to operate an external
breaker, which MUST be fitted if over voltage protection is
required.

Incorrect setting would cause the generator output voltage to
collapse at no-load or on removal of load, and the LED to be
illuminated.

The correct setting is 300 volts +/-5% across terminals E1,
E0. Clockwise adjustment of the OVER/V control
potentiometer will increase the voltage at which the circuit
operates.

4.7.1.4 TRANSIENT LOAD SWITCHING
ADJUSTMENTS
AVR Types SX421, MX341 and MX321

The additional function controls of DIP and DWELL are
provided to enable the load acceptance capability of the
generating set to be optimised. The overall generating set
performance depends upon the engine capability and
governor response, in conjunction with the generator
characteristics.

It is not possible to adjust the level of voltage dip or recovery
independently from the engine performance, and there will
always be a 'trade off' between frequency dip and voltage dip.

DIP
AVR Types SX421, MX341 and MX321

AVR Types SX421, MX341 and MX321
The dip function control potentiometer adjusts the slope of the
voltage/speed (Hz) characteristic below the knee point as
shown below :

Fig. 8

DWELL
AVR Type MX321

The dwell function introduces a time delay between the
recovery of voltage and recovery of speed.

The purpose of the time delay is to reduce the generator kW
below the available engine kW during the recovery period,
thus allowing an improved speed recovery.

Again this control is only functional below the "knee point", i.e.
if the speed stays above the knee point during load switching
there is no effect from the DWELL function setting.

Clockwise adjustment gives increased recovery time.

The graphs shown above are representations only, since it is
impossible to show the combined effects of voltage regulator
and engine governor performance.

4.7.1.5 RAMP

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AVR Type MX321

The RAMP potentiometer enables adjustment of the time
taken for the generator's initial build up to normal rated
voltage during each start and run up to speed. The
potentiometer is factory set to give a ramp time of three
seconds, which is considered to be suitable for most
applications. This time can be reduced to one second by
turning the pot. fully counter clockwise, and increased to eight
seconds by turning the pot. fully clockwise.

4.7.2 TRANSFORMER CONTROLLED
GENERATORS - TRANSFORMER ADJUSTMENT

Normally no adjustment is required but should the no-load
voltage and/or on-load voltage be unacceptable, adjustment
of the transformer air gap can be made as follows.

Stop the generator. Remove transformer cover box. (Normally
left hand side of the terminal box when viewed from the non
drive end).

Slacken the three transformer mounting bolts along the top of
the transformer.

Start the set with a voltmeter connected across the main
output terminals.

Adjust the air gap between the transformer top lamination
section and the transformer limbs to obtain required voltage
on no-load. Slightly tighten the three mounting bolts. Switch
load 'on' and 'off' two or three times. Application of load will
normally raise the voltage setting slightly. With the load 'off'
recheck the no-load voltage.

Readjust air gap and finally tighten mounting bolts.
Refit the access cover.

Failure to refit covers can result in
operator personal injury or death.

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!

4.8 ACCESSORIES

Refer to the "ACCESSORIES" - Section 6 of t his Manual for
setting up procedures related to generator mounted
accessories.

If there are accessories for control panel mounting supplied
with the generator refer to the specific accessory fitting
procedures inserted inside the back cover of this book.

SECTION 5

g

INSTALLATION - PART 2

5.1 GENERAL

The extent of site installation will depend upon the generating
set build, e.g. if the generator is installed in a canopied set
with integral switchboards and circuit breaker, on site
installation will be limited to connecting up the site load to the
generating set output terminals . In this case reference should
be made to the generating set manufacturer's instruction book
and any pertinent local regulations. If the generator has been
installed on a set without switchboard or circuit breaker the
following points relating to connecting up the generator should
be noted.

5.2 GLANDING

The terminal box is most conveniently glanded on either the
right or left hand side. Both panels are removable for
drilling/punching to suit glands/or glanding boxes. If single
core cables are taken through the terminal box side panel an
insulated or non-magnetic gland plate should be fitted.

Incoming cables should be supported from either below or
above the box level and at a sufficient distance from the
centre line of the gener ating set so as to avoid a tight radius
at the point of entry into the terminal box panel, and allow
movement of the generator set on its anti-vibration mountings
without excessive stress on the cable.

Before making final connections, test the insulation resistance
of the windings. The AVR should be disconnected during this
test.

A 500V Megger or similar instrument should be used. Should
the insulation resistance be less than 5MΩ the windings must
be dried out as detailed in the Service and Maintenance
section of this manual.

When making connections to the terminals the incoming cable
termination should be placed on top of the winding lead
termination(s) and clamped with the nut provided.

Important ! To avoid the possibility of swarf entering

any electrical components in the terminal
box, panels must be removed for drilling.

5.3 EARTHING

The neutral of the generator is not bonded to the generator
frame as supplied from the factory. An earth terminal is
provided inside the terminal box adjacent to the main
terminals. Should it be required to operate with the neutral
earthed a substantial earth conductor (normally equivalent to
one half of the section of the line conductors) must be
connected between the neutral and the earth terminal inside
the terminal box. Additional earth terminals are provided on
the generator feet. These should be already bonded to the
generating set bedplate by the generating set builder, but will
normally be required to be connected to the site earth system.

Reference to local electricity regulations

Caution !

or safety rules should be made to ensure
correct earthing procedures have been
followed.

5.4 PROTECTION

It is the responsibility of the end user and his
contractors/subcontractors to ensure that the overall system
protection meets the needs of any inspectorate, local
electricity authority or safety rules, pertaining to the site
location.

To enable the system designer to achieve the necessary
protection and/or discrimination, fault current curves are
available on request from the factory, together with generator
reactance values to enable fault current calculations to be
made.

Incorrect installation and/or protective
systems can result in personal injury
and/or equipment damage. Installers must
be qualified to perform electrical

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installation work.

!

5.5 COMMISSIONING

Ensure that all external cabling is correct and that all the
generating set manufacturer's pre-running checks have been
carried out before starting the set.

The generator AVR controls will have been adjusted during
the generating set manufacturer's tests and should normally
not require further adjustment.

Should malfunction occur during commissioning refer to
Service and Maintenance section 'Fault Finding' procedure
(subsection 7.4).

SECTION 6

ACCESSORIES

Generator control accessories may be fitted, as an option, in
the generator terminal box. If fitted at the time of supply, the
wiring diagram(s) in the back of this book shows the
connections. When the options are supplied separately, fitting
instructions are provided with the accessory.

The following matrix indicates availability of accessories with
the differing AVRs.

Note the SX460 is not suitable for operation with accessories.

Paralleling

AVR Model

SX460 X X X X

AS440 O O O
MX341 O O O
MX321 O O O

Droop or

Astatic

6.1 REMOTE VOLTAGE ADJUST (ALL AVR TYPES)

A remote voltage adjust (hand trimmer) can be fitted.
SX460 Remove link 1-2 on the AVR and

AS440 Remove link 1-2 at the auxiliary
MX341 and MX321 and connect adjuster to terminals 1

6.2 PARALLEL OPERATION

Understanding of the following notes on parallel operation is
useful before attempting the fitting or setting of the droop kit
accessory. When operating in parallel with other generators or
the mains, it is essential that the phase sequence of the
incoming generator matches that of the busbar and also that
all of the following conditions are met before the circuit
breaker of the incoming generator is closed on to the busbar
(or operational generator).

1. Frequency must match within close limits.

2. Voltages must match within close limits.

3. Phase angle of voltages must match within close limits.
A variety of techniques, varying from simple
synchronising lamps to fully automatic synchronisers, can
be used to ensure these conditions are met.

Important ! Failure to meet conditions 1, 2, and 3 when

closing the cricuit breaker, will generate
excessive mechanical and electrical
stresses, resulting in equipment damage.

Once connected in parallel a minimum instrumentation level
per generator of voltmeter, ammeter, wattmeter (measuring
total power per generator), and frequency meter is required in
order to adjust the engine and generator controls to share kW
in relation to engine ratings and kVAr in relation to generator
ratings.

Manual
Voltage

Regulator

connect adjuster to terminals 1 and 2.

terminals
and 2.

Var/PF
Control

Current

Limit

It is important to recognise that :

1. True kW are derived from the engine, and speed
governor characteristics determine the kW sharing
between sets

and

2. kVAr are derived from the generator, and excitation
control characteristics determine the kVAr sharing.
Reference should be made to the generating set
manufacturer's instructions for setting the governor
controls.

6.2.1 DROOP

The most commonly used method of kVAr sharing is to create
a generator voltage characteristic which falls with decreasing
power factor (inc re as in g kV Ar). This is achieved wit h a c urrent
transformer (C.T.) which provides a signal dependent on
current phase angle (i.e. power factor) to the AVR.

The current transformer has a burden resistor on the AVR
board, and a percentage of the burden resistor voltage is
summed into the AVR circuit. Increasing droop is obtained by
turning the DROOP control potentiometer clockwise.

The diagrams below indicate the effect of droop in a simple
two generator system

: -

Generally 5% droop at full load current zero p.f. is sufficient to
ensure kVAr s haring.

If the droop accessory has been supplied with the generator it
will have been tested to ensure correct polarity and set to a
nominal level of droop. The final level of droop will be set
during generating set commissioning.

The following setting procedure will be found to be helpful.

6.2.1.1 SETTING PROCEDURE

Depending upon available load the following settings should
be used - all are based on rated current level.

0.8 P.F. LOAD (at full load current) SET DROOP TO 3%
Zero P.F. LOAD (at full load current) SET DROOP TO 5%

Setting the droop with low power factor load is the most
accurate. Run each generator as a single unit at rated
frequency or rated frequency + 4% depending upon type of
governor and nominal voltage. Apply available load to rated
current of the generator. Adjust 'DROOP' control
potentiometer to give droop in line with above table.
Clockwise rotation increases amount of droop. Refer to Fig
9a, 9b, 9c or 9d for potentiometer locations.

Note 1)
Reverse polarity of the C.T. will raise the generator voltage

with load. The polarities S1-S2 shown on the wiring diagrams
are correct for clockwise rotation of the generator looking at
the drive end. Reversed rotation requires S1-S2 to be
reversed.

Note 2)
The most important aspect is to set all generators equal. The

precise level of droop is less critical.
Note 3)

A generator ope rated as a single un it with a droop cir cuit set
at rated load 0.8 power factor is unable to maintain the usual
+/-0.5% regulation. A shorting switch can be connected
across S1-S2 to restore regulation for single running.

Important ! LOSS OF FUEL to an engine can cause its

generator to motor with consequent damage
to the generator windings. Reverse power
relays should be fitted to trip main circuit
breaker.
LOSS OF EXCITATION to the generator can
result in large current oscillations with
consequent damage to generator windings.
Excitation loss detection equipment should
be fitted on trip main circuit breaker.

6.2.2 ASTATIC CONTROL

The 'droop' current transformer can be used in a connection
arrangement which enables the normal regulation of the
generator to be maintained when operating in parallel. This
feature is only supplied from the factory as a fitted droop kit,
however, if requested at the time of order, the diagrams inside
the back cover of this book will give the necessary site
connections. The end user is required to provide a shorting
switch for the droop current transformer secondary.

Should the generator be required to be converted from
standard droop to 'astatic' control, diagrams are available on
request.

The setting procedure is exactly the same as for DROOP.
(Subsection 6.2.1.1)

Important ! When using this connection arrangement a

shorting switch is required across each C.T.
burden (terminals S1 and S2.)The switch
must be closed a) when a generating set is
not running and b) when a generating set is
selected for single running.

6.3 MANUAL VOLTAGE REGULATOR (MVR) -

MX341 and MX321 AVR

This accessory is provided as an 'emergency' excitation
system, in the event of an AVR failure.

Powered from the PMG output the unit is manually set, but
automatically controls the excitation current, independent of
generator voltage or frequency.

The unit is provided with 'MANUAL', 'OFF', 'AUTO' switching
facility.

'MANUAL'

- position connects the exciter field to the MVR output.

Generator output is then controlled by the operator adjusting
the excitation current.

'OFF'

- disconnects the exciter field from both MVR and the normal

AVR.

'AUTO'

- connects the exciter field to the normal AVR and the

generator output is controlled at the pre-set voltage under
AVR control.

switching mode of operation should be carried out with the
generator set stationary to avoid voltage surges on the
connected load, although neither the MVR nor AVR will be
damaged should the switching be carried out with the set
running.

6.4 OVERVOLTAGE DE-EXCITATION BREAKER

MX321 AVR

This accessory provides positive interruption of the excitation
power in the event of overvoltage due to loss of sensing or
internal AVR faults including the output power device.

With the MX321 AVR this accessory is supplied loose for
fitting in the control panel.

Important ! When the circuit breaker is supplied loose,

the AVR is fitted with a link on terminals K1­K2 to enable operation of the AVR. When
connecting the circuit breaker this link must
be removed.

6.4.1 RESETTING THE BREAKER

In the event of operation of the circuit breaker, indicated by
loss of generator output voltage, manual resetting is required.
When in the "tripped" state the circuit breaker switch lever
shows "OFF". To reset move the switch lever to the position
showing "ON".

When fitted in the generator, access to the breaker is gained
by removal of the AVR access cover.

Terminals which are LIVE with the
generating set running are exposed when
the AVR access cover is removed.
Resetting of the circuit breaker MUST be

Danger !

The circuit breaker is mounted on the AVR mounting bracket
either to the left or to the right of the AVR depending upon
AVR position. After resetting the circuit breaker replace the
AVR access cover before restarting the generating set.
Should resetting of the circuit breaker not restore the
generator to normal operation, refer to subsection 7.5.

carried out with the generating set
stationary, and engine starting circuits
disabled.

6.5 CURRENT LIMIT - MX321 AVR

These accessories work in conjunction with the AVR circuits
to provide an adjustment to the level of current delivered into
a fault. One current transformer (CT) per phase is fitted to
provide current limiting on any line to line or line to neutral
fault.

Note: The W phase CT can also provide "DROOP". Refer to

6.2.1.1 for setting droop independent of current limit.

Adjustment means is provided with the "I/LIMIT" control
potentiometer on the AVR. Refer to Fig. 9d for location. If
current limit transformers are supplied with the generator the
limit will be set in accordance with the level specified at t he
time of order, and no further adjustment will be necessary.
However, should the level need to be adjusted, refer to the
setting procedure given in 6.5.1.

6.5.1 SETTING PROCEDURE

Run the generating set on no-load and check that engine
governor is set to control nominal speed.

Stop the generating set. Remove the link between terminals
K1-K2 at the auxi liary termi nal block and connec t a 5A swit ch
across the terminals K1-K2.

Turn the "I/LIMIT" control potentiometer fully anticlockwise.
Short circuit the stator winding with a bolted 3 phase short at
the main terminals. An AC current clip-on ammeter is required
to measure the winding lead current.

With the switch across K1-K2 open start the generating set.
Close the switch across K1-K2 and turn the "I/LIMIT" control

potentiometer clockwise until required current level is
observed on the clip-on ammeter. As soon as correct setting
is achieved open the K1-K2 switch.

Should the current collapse during the setting procedure, the
internal protective circuits of the AVR will have operated. In
this event shut down the set and open the K1-K2 switch.
Restart the set and run for 10 minutes with K1-K2 switch
open, to cool the generator windings, before attempting to
resume the setting procedure.

Important ! Failure to carry out the correct COOLING

procedure, may cause overheating and
consequent damage to the generator
windings.

6.6 POWER FACTOR CONTROLLER (PFC3)

This accessory is primarily designed for those generator
applications where operation in parallel with the mains supply
is required.

Protection against loss of mains voltage or generator
excitation is not included in the unit and the system designer
must incorporate suitable protection.

The electronic control unit requires both droop and kVAr
current transformers. When supplied with the generator,
wiring diagrams inside the back cover of this manual show the
connections and the additional instruction leaflet provided
gives details of setting procedures for the power factor
controller (PFC3).

The unit monitors the power factor of the generator current
and adjusts excitation to maintain the power factor constant.

This mode can also be used to control the power factor of the
mains if the point of current monitoring is moved to the mains
cables. Refer to the factory for appropriate details.

It is also possible to operate the unit to control kVAr of the
generator if required. Refer to the factory for appropriate
details.

SECTION 7

g

SERVICE AND MAINTENANCE

As part of routine maintenance procedures, periodic attention
to winding condition (particularly when generators have been
idle for a long period) and bearings is recommended. (Refer
to subsections 7.1 and 7.2 respectively).

When generators are fitted with air filters regular inspection
and filter maintenance is required. (Refer to subsection 7.3).

7.1 WINDING CONDITION

Service and fault finding procedures
present hazards which can result in severe
personal injury or death. Only personnel
qualified to perform electrical and
mechanical service should carry out these
procedures. Ensure engine starting

Warnin

Guidance of Typical Insulation Resistance [IR]

Values

The following is offered as general information about IR
values and is aimed at providing guidance about the typical IR
values for generators from new through to the point of
refurbishment.

New Machines

The generators Insulation Resistance, along with many other
critical factors, will have been measured during the alternator
manufacturing process. The generator will have been
transported with an appropriate packaging suitable for the
method of delivery to the Generating Set assemblers works.
Where we expect it to be stored in a suitable location
protected from adverse environmental conditions.

However, absolute assurance that the generator will arrive at
the Gen-set production line with IR values still at the factory
test levels of above 100 MΩ cannot be guaranteed.

At Generating Set Manufacturers Works

The generator should have been transported and stored such
that it will be delivered to the assembly area in a clean dr y
condition. If held in appropriate storage conditions the
generator IR value should typically be 25 MΩ.

If the unused/new generators IR values fall below 10 MΩ then
a drying out procedure should be implemented by one of the
processes outlined below before being despatched to the end
customer’s site. Some investigation should be undertaken into
the storage conditions of the generator while on site.

Generators in Service

Whilst It is known that a generator will give reliable service
with an IR value of just 1.0 MΩ. For a relatively new generator
to be so low it must have been subjected to inappropriate
operating or storage conditions.

circuits are disabled before commencing

!

service or maintenance procedures.
Isolate any anti-condensation heater
supply.

Any temporarily reduction in IR values can be restored to
expected values by following one of the drying out
procedures.

7.1.1 WINDING CONDITION ASSESSMENT

Caution !

The condition of the windings can be assessed by
measurement of insulation resistance [IR] between phase to
phase, and phase to earth.

Measurement of winding insulation should be carried out : -

1. As part of a periodic maintenance plan.

2. After prolonged periods of shutdown.

3. When low insulation is suspected, e.g. damp or wet
windings.

Care should be taken when dealing with windings that are
suspected of being excessively damp or dirty. The initial
measurement of the [IR] Insulation Resistance should be
established using a low voltage (500V) megger type
instrument. If manually powered the handle should initially be
turned slowly so that the full test volta ge will not be applied,
and only applied for long enough to very quickly assess the
situation if low values are suspected or immediately indicated.

Full megger tests or any other form of high voltage test should
not be applied until the windings have been dried out and if
necessary cleaned.

The AVR should be disconnected and the
Resistance Temperature Detector (R.T.D.)
leads grounded during this test.

Procedure for Insulation Testing

Disconnect all electronic components, AVR, electronic
protection equipment etc. Ground the [RTD's] Resistance
Temperature Detection devices if fitted. Short out the diodes
on the rotating diode assembly. Be aware of all components
connected to the system under test that could cause false
readings or be damaged by the test voltage.

Carry out the insulation test in accordance with the ‘operating
instructions for the test equipment.

The measured value of insulation resistance for all windings
to earth and phase to phase should be compared with the
guidance given above for the various 'life stages' of a
generator. The minimum acceptable value must be greater
than 1.0 MΩ.

If low winding insulation is confirmed use one or more of
the methods, given below, for drying the winding should
be carried out.

1. METHODS OF DRYING OUT GENERATORS

Cold Run

Consider a good condition generator that has not been run for
some time, and has been standing in damp, humid conditions.

It is possible that simply running the gen set unexcited – AVR
terminals K1 K2 open circuit - for a period of say 10 minutes
will sufficiently dry the surface of the windings and raise the IR
sufficiently, to greater than 1.0 MΩ , and so allow the unit to
be put into service.

Blown Air Drying

Remove the covers from all apertures to allow the escape of
the water-laden air. During drying, air must be able to flow
freely through the generator in order to carry off the moisture.

Direct hot air from two electrical fan heaters of around 1 – 3
kW into the generator air inlet apertures. Ensure the heat
source is at least 300mm away from the windings to avoid
over heating and damage to the insulation.

Apply the heat and plot the insulation value at half hourly
intervals. The process is complete when the parameters
covered in the section entitled, ‘Typical Drying Out Curve’, are
met.

Remove the heaters, replace all covers and re-commission as
appropriate .

If the set is not to be run immediately ensure that the
anticondensation heaters are energised, and retest prior to
running.

Short Circuit Method

NOTE: This process should only be performed by a
competent engineer familiar with safe operating practices
within and around generator sets of the type in question.

Ensure the generator is safe to work on, initiate all mechanical
and electrical safety procedures pertaining to the genset and
the site.

Bolt a short circuit of adequate current carrying capacity,
across the main terminals of the ge nerator. The sho rting link
should be capable of taking full load current.

Disconnect the cables from terminals “X” and “XX” of the
AVR.

Connect a variable dc supply to the “X” (positive) and “XX”
(negative) field cables. The dc supply must be able to provide
a current up to 2.0 Amp at 0 - 24 Volts.

Position a suitable ac ammeter to measure the shorting link
current.

Set the dc supply voltage to zero and start the generating set.
Slowly increase the dc voltage to pass current through the
exciter field winding. As the excitation current increases, so
the stator current in the shorting link will inc rease. This stator
output current level must be monitored, and not allowed to
exceed 80% of the generators rated output current.

After every 30 minutes of this exercise:
Stop the generator and switch off the separate excitation

supply, and measure and record the stator winding IR values,
and plot the results. The resulting graph should be compared
with the classic shaped graph. This drying out procedure is
complete when the parameters covered in the section entitled
'Typical Drying Out Curve' are met.

Once the Insulation Resistance is raised to an acceptable
level - minimum value 1.0 MΩ − the dc supply may be
removed and the exciter field leads “X” and “XX” re-connected
to their terminals on the AVR.

Rebuild the genset, replace all covers and re-commission as
appropriate.

If the set is not to be run immediately ensure that the
anticondensation heaters are energised, and retest the
generator prior to running.

TYPICAL DRYING OUT CURVE

Whichever method is used to dry out the generator the
resistance should be measured every half-hour and a curve
plotted as shown. (fig 6.)

The illustration shows a typical curve for a machine that has
absorbed a considerable amount of moisture. The curve
indicates a temporary increase in resistance, a fall and then a
gradual rise to a steady state. Point ‘A’, the steady state, must
be greater than 1.0 MΩ. (If the windings are only slightly
damp the dotted portion of the curve may not appear).

For general guidance expect that the typical time to reach
point 'A' will be :

1 hour for a BC16 /18,
2 hours for a UC22/27
3 hours for an HC4,5,6&7
Drying should be continued after point “A” has been reached
for at least one hour.

It should be noted that as winding temperature increases,
values of insulation resistance may significantly reduce.
Therefore, the reference values for insulation resistance can
only be established with windings at a temperature of
approximately 20°C.

If the IR value remains below 1.0 MΩ, even after the above
drying methods have been properly conducted, then a
Polarisation Index test [PI] should be carried out.

If the minimum value of 1.0 MΩ for all components cannot be
achieved rewinding or refurbishment of the generator will be
necessary.

The generator must not be put into service until the
minimum values can be achieved.

Important ! The short circuit must not be applied with

the AVR connected in circuit. Current in
excess of the rated generator current will
cause damage to the windings.

After drying out, the insulation resistances should be
rechecked to verify minimum resistances quoted above are
achieved.
On re-testing it is recommended that the main stator
insulation resistance is checked as follows :­Separate the neutral leads

Ground V and W phase and megger U phase to ground
Ground U and W phase and megger V phase to ground
Ground U and V phase and megger W phase to ground

If the minimum value of 1.0MΩ is not obtained, drying out
must be continued and the test repeated.

All bearings are supplied sealed for life and are, therefore, not
regreasable.

Important ! The life of a bearing in service is subject to

the working conditions and the
environment.

Important ! Long stationary periods in an environment

where there is vibration can cause false
brinnelling which puts flats on the ball and
grooves on the races. Very humid
atmospheres or wet conditions can emulsify
the grease and cause corrosion.

Important ! High axial vibration from the engine or

misalignment of the set will stress the
bearing.

The bearing, in service, is affected by a variety of factors that
together will determine the beari ng life. We recommend that
the health of the bearings be monitored, using ‘spike energy’
vibration monitoring equipment. This will allow the timely
replacement of bearings, that exhibit a deteriorating trend,
during a major engine overhaul.

If excessive heat, noise or vibration is detected, change the
bearing as soon as practicable. Failure to do so could result in
bearing failure.

In the event that ‘spike energy’ vibration monitoring equipment
is not available, it is strongly recommend that consideration
be given to changing the bearing during each ‘major engine
overhaul’.

Belt driven application will impose an additional load on
bearings. The bearing life will therefore be significantly
affected. It is important that the side load limits given in
SECTION 3 are not exceeded and the health of the bearing is
monitored more closely.

7.2 BEARINGS

7.3 AIR FILTERS

The frequency of filter maintenance will depend upon the
severity of the site conditions. Regular inspection of the
elements will be required to establish when cleaning is
necessary.

7.3.1 CLEANING PROCEDURE

Removal of filter elements enables access
to LIVE parts. Only remove elements with
the generator out of service.

Danger !

Remove the filter elements from the filter frames. Immerse or
flush the element with a suitable detergent until the element is
clean. Dry elements thoroughly before refitting.

7.4 FAULT FINDING

Important ! Before commencing any fault finding

procedure examine all wiring for broken or
loose connections.

Four types of excitation control system, involving four types of
AVR, can be fitted to the range of generators covered by this
manual. The systems can be identified by a combination of
AVR type, where applicable, and the last digit of the generator
frame size designation. Refer to the generator nameplate then
proceed to the appropriate subsection as indicated below :-

DIGIT EXCITATION CONTROL SUBSECTION

6 SX460 AVR 7.4.1
4 AS440 AVR 7.4.2
4 7.4.3
5 Transformer control 7.4.4
3 MX341 AVR 7.4.5
3 MX321 AVR 7.4.6

7.4.1 SX460 AVR - FAULT FINDING

1. Check speed

No voltage

build-up when

starting set

Unstable voltage
either on no-load

or with load

High voltage

either on no-load

or with load

Low voltage

no-load

Low voltage

on-load

2. Check residual voltage. Refer to
subsection 7.4.7.

3. Follow Separate Excitation Test
Procedure to check generator and
AVR.

1. Check speed stability.

2. Check stability setting. Refer to
subsection 4.6.

1. Check speed.

2. Check that generator load is not
capacitive (leading power factor).

1. Check speed.

2. Check link 1-2 or external hand
trimmer leads for continuity.

1. Check speed.

2. Check UFRO setting. Refer to
subsection 4.7.1.1.

3. Follow Separate Excitation
Procedure to check generator and
AVR. Refer to subsection 7.5.

7.4.2 SX440 AVR - FAULT FINDING

1. Check link K1-K2 on auxiliary
terminals.

No voltage

build-up when

starting set

Unstable voltage
either on no-load

or with load

High voltage

either on no-load

or with load

Low voltage

no-load

Low voltage

on-load

2. Check speed

3. Check residual voltage. Refer to
subsection 7.4.7.

4. Follow Separate Excitation Test
Procedure to check generator and
AVR. Refer to subsection 7.5.

1. Check speed stability.

2. Check stability setting. Refer to
subsection 4.6.

1. Check speed.

2. Check that generator load is not
capacitive (leading power factor).

1. Check speed.

2. Check link 1-2 or external hand
trimmer leads for continuity.

1. Check speed.

2. Check UFRO setting. Refer to
subsection 4.7.1.1.

3. Follow Separate Excitation
Procedure to check generator and
AVR. Refer to subsection 7.5.

7.4.3 SX421 AVR - FAULT FINDING

1. Check circuit breaker ON. Refer to
subsection 6.4.1.

No voltage

build-up when

starting set

Unstable voltage
either on no-load

or with load

High voltage

either on no-load

or with load

Low voltage

no-load

Low voltage

on-load

Excessive

voltage/speed

dip on load

switching

2. Check speed

3. Check residual voltage. Refer to
subsection 7.4.7.

4. Follow Separate Excitation Test
Procedure to check generator and
AVR. Refer to subsection 7.5.

1. Check speed stability.

2. Check stability setting. Refer to
subsection 4.6.

1. Check speed.

2. Check link 1-2 or external hand
trimmers leads for continuit y. Check
continuity of leads 7-8 and P3-P2 for
continuity.

3. Check that generator load is not
capacitive (leading power factor).

1. Check speed.

2. Check link 1-2 or external hand
trimmer leads for continuity.

1. Check speed.

2. Check UFRO setting. Refer to
subsection 4.7.1.1.

3. Follow Separate Excitation
Procedure to check generator and
AVR. Refer to subsection 7.5.

1. Check governor response.

2. Refer to generating set manual.
Check ‘DIP’ setting. Refer to
subsection 4.7.1.4.

7.4.4 TRANSFORMER CONTROL - FAULT FINDING

No voltage

build-up when

starting set

Low voltage

High voltage

Excessive

voltage/speed

dip on load

switching

1. Check transformers rectifiers.

2. Check transformer secondary
winding for open circuit.

1. Check speed.

2. Check transformer air gap setting.
Refer to subsection 4.7.2.

1. Check speed.

2. Check transformer air gap setting.
Refer to subsection 4.7.2.

3. Check transformer secondary
winding for open circuit.

1. Check speed drop on-load.

2. Check transformers rectifiers.

3. Check transformer air gap setting.
Refer to subsection 4.7.2.

7.4.5 MX341 AVR - FAULT FINDING

1. Check link K1-K2 on auxiliary

No voltage

build-up when

starting set

Loss of voltage

when set runninig

Generator
voltage high
followed by

collapse

Voltage unstable,

either on no-load

or with load

Low voltage

on-load

Excessive

voltage/speed

dip on load

switching

Sluggish

recovery on load

switching

terminals

2. Follow Separate Excitation Test
Procedure to check machine and
AVR. Refer to subsection 7.5.

1. First stop and restart set. If no
voltage or voltage collapses after
short time, follow Separate Excitation
Test Procedure. Refer to subsection

7.5.

1. Check sensing leads to AVR.

2. Refer to Separate Excitation Test
Procedure. Refer to subsection 7.5.

1. Check speed stability.

2. Check “STAB” setting. R efer to Load
Testing section for procedure. Refer
to subsection 4.6.

1. Check speed.

2. If correct check “UFRO” setting.
Refer to subsection 4.7.1.1.

1. Check governor response. Refer to
generating set manual. Check “DIP”
setting. Refer to subsection 4.7.1.4.

1. Check governor response. Refer to
generating set manual.

7.4.6 MX321 AVR - FAULT FINDING

No voltage

build-up when

starting set

Voltage very slow

to build up

Loss of voltage

when set running

Generator
voltage high
followed by

collapse

Voltage unstable,
either on no-load

or with load

Low voltage

on-load

Excessive

voltage/speed dip

on load switching

Sluggish

recovery on load

switching

1. Check link K1-K2 on auxiliary
terminals. Follow Separate Excitation
Test Procedure to check machine
and AVR. Refer to subsection 7.5.

1. Check setting of ramp potentiometer.
Refer to 4.7.1.5.

1. First stop and restart set. If no
voltage or voltage collapses after
short time, follow Separate Excitation
Test Procedure. Refer to subsection

7.5.

1. Check sensing leads to AVR.

2. Refer to Separate Excitation Test
Procedure. Refer to subsection 7.5.

1. Check speed stability.

2. Check “STAB” setting. Refer to Load
Testing section for procedure. Refer
to subsection 4.6.

1. Check speed.

2. If correct check “UFRO” setting.
Refer to subsection 4.7.1.1.

1. Check governor response. Refer to
generating set manual. Check “DIP”
setting. Refer to subsection 4.7.1.4.

1. Check governor response. Refer to
generating set manual. Check
“DWELL” setting. Refer to Load
Testing section 4.7.1.4.

7.4.7 RESIDUAL VOLTAGE CHECK

This procedure is applicable to generators with either SX460
or SX440 or SX421 AVR.

With the generator set stationary remove AVR access cover
and leads X and XX from the AVR.

Start the set and measure voltage across AVR terminals 7-8
on SX460 AVR or P2-P3 on SX440 or SX421 AVR.

Stop the set, and replace leads X and XX on the AVR
terminals. If the measured voltage was above 5V the
generator should operate normally.

If the measured voltage was under 5V follow the procedure
below.

Using a 12 volt d. c. battery as a supply clip leads from battery
negative to AVR terminal XX, and from battery positive
through a diode to AVR terminal X. See Fig. 10.

Important ! A diode must be used as shown below to

ensure the AVR is not damaged.

Important ! If the generating set battery is used for field

flashing the generator main stator neutral
must be disconnected from earth.

Restart the set and note output voltage from main stator,
which should be approximately nominal voltage, or voltage at
AVR terminals 7 and 8 on SX460, P2-P3 on SX440 or SX421
which should be between 170 and 250 volts.

Stop the set and unclip battery supply from terminals X and
XX. Restart the set. The generator should now operate
normally. If no voltage build-up is obtained it can be assumed
a fault exists in either the generator or the AVR circuits.
Follow the SEPARATE EXCIT ATION TEST PROCEDURE to
check generator windings, rotating diodes and AVR. Refer to
subsection 7.5.

7.5 SEPARATE EXCITATION TEST PROCEDURE

The generator windings, diode assembly and AVR can be
checked using the appropriate following section.

7.5.1 GENERATOR WINDINGS, ROTATING DIODES and
PERMANENT MAGNET GENERATOR (PMG)

7.5.2 EXCITATION CONTROL TEST.

7.5.1 GENERATOR WINDINGS, ROTATING DIODES
and PERMANENT MAGNET GENERATOR (PMG)

Important ! The resistances quoted apply to a standard

winding. For generators having windings or
voltages other than those specified refer to
factory for details. Ensure all disconnected
leads are isolated and free from earth.

Important ! Incorrect speed setting will give

proportional error in voltage output.

CHECKING PMG

Start the set and run at rated speed. Measure the voltages at
the AVR terminals P2, P3 and P4. These should be balanced
and within the following ranges :-

50Hz generators - 170-180 volts
60Hz generators - 200-216 volts

Should the voltages be unbalanced stop the set, remove the
PMG sheet metal cover from the non drive endbracket and
disconnect the multipin plug in the PMG output leads. Check
leads P2, P3, P4 for continuity. Check the PMG stator
resistances between output leads. These should be balanced
and within +/-10% of 2.3 ohms. If resistances are unbalanced
and/or incorrect the PMG stator must be replaced. If the
voltages are balanced but low and the PMG stator winding
resistances are correct - the PMG rotor must be replaced.

CHECKING GENERATOR WINDINGS AND
ROTATING DIOD E S

This procedure is carried out with leads X and XX
disconnected at the AVR or transformer control rectifier bridge
and using a 12 volt d.c. supply to leads X and XX.

Start the set and run at rated speed.
Measure the voltages at the main output terminals U, V and

W. If voltages are balanced and within +/-10% of the
generator nominal voltage, refer to 7.5.1.1.

Check voltages at AVR terminals 6, 7 and 8. These should be
balanced and between 170-250 volts.

If voltages at main terminals are balanced but voltage at 6, 7
and 8 are unbalanced, check continuity of leads 6, 7 and 8.
Where an isolating transformer is fitted (MX321 AVR) check
transformer windings. If faulty the transformer unit must be
replaced.

If voltages are unbalanced, refer to 7.5.1.2.

7.5.1.1 BALANCED MAIN TERMINAL VOLTAGES

If all voltages are balanced within 1% at the main termina ls, it
can be assumed that all exciter windings, main windings and
main rotating diodes are in good order, and the fault is in the
AVR or transformer control. Refer to subsection 7.5.2 for test
procedure.

If voltages are balanced but low, there is a fault in the main
excitation windings or rotating diode assembly. Proceed as
follows to identify :-

Rectifier Diodes

The diodes on the main rectifier assembly can be checked
with a multimeter. The flexible leads connected to each diode
should be disconnected at the terminal end, and the forward
and reverse resistance checked. A healthy diode will indicate
a very high resistance (infinity) in the reverse direction, and a
low resistance in the forward direction. A faulty diode will give
a full deflection reading in both directions with the test meter
on the 10,000 ohms scale, or an infinity reading in both
directions.

On an electronic digital meter a healthy diode will give a low
reading in one direction, and a high reading in the other.

Replacement of Faulty Diodes

The rectifier assembly is split into two plates, the positive and
negative, and the main rotor is connected across these plates.
Each plate carries 3 diodes, the negative plate carrying
negative biased diodes and the positive plate carrying positive
biased diodes. Care must be taken to ensure that the correct
polarity diodes are fitted to each respective plate. When fitting
the diodes to the plates they must be tight enough to ensure a
good mechanical and electrical contact, but should not be
overtightened. The recommended torque tightening is 4.06 -

4.74Nm (36-42lb in).

Surge Suppresso r

The surge suppressor is a metal-oxide varistor connected
across the two rectifier plates to prevent high transient
reverse voltages in the field winding from damaging the
diodes. This device is not polarised and will show a virtually
infinite reading in both directions with an ordinary resistance
meter. If defective this will be visible by inspection, since it will
normally fail to short circuit and show signs of disintegration.
Replace if faulty.

Main Excitation Windings

If after establishing and correcting any fault on the rectifier
assembly the output is still low when separately excited, then
the main rotor, exciter stator and exciter rotor winding
resistances should be checked (see Resistance Charts), as
the fault must be in one of these windings. The exciter stator
resistance is measured across leads X and XX. The exciter
rotor is connected to six studs which also carry the diode lead
terminals. The main rotor winding is connected across the two
rectifier plates. The respective leads must be disconnected
before taking the readings.

Resistance values should be within +/-10% of the values
given in the table below :-

SIZE

UC22C 0.59 21 28 138 0.142
UC22D 0.64 21 28 138 0.142
UC22E 0.69 20 30 155 0.156
UC22F 0.83 20 30 155 0.156
UC22G 0.94 20 30 155 0.156

UC27C 1.12 20 - - 0.156
UC27D 1.26 20 - - 0.156
UC27E 1.34 20 - - 0.182
UC27F 1.52 20 - - 0.182
UC27G 0.69 20 - - 0.182
UC27H 0.82 20 - - 0.182

Main

Rotor

Exciter Stator FRAME

Type 1 Type 2* Type 3**

Exciter

Rotor

UCD27J 2.08 20 - - 0.182
UCD27K 2.08 20 - - 0.182

* Used with 1 phase transformer controlled 3 phase or 1
phase generators.
** Used with 3 phase transformer controlled 3 phase
generators.

7.5.1.2 UNBALANCED MAIN TERMINAL VOLTAGES

If voltages are unbalanced, this indicates a fault on the main
stator winding or main cables to the circuit breaker.
NOTE : Faults on the stator winding or cables may also cause
noticeable load increase on the engine when excitation is
applied. Disconnect the main cables and separate the winding
leads U1-U2, U5-U6, V1-V2, V5-V6, W1-W2, W5-W6 to
isolate each winding section. (U1-L1, U2-L4 on single phase
generators).

Measure each section resistance - values should be balanced
and within +/-10 % of the value given b elow:-

AVR CONTROLLED GENERATORS

FRAME

SIZE

UC22C 0.09 0.14 0.045 0.03
UC22D 0.065 0.1 0.033 0.025
UC22E 0.05 0.075 0.028 0.02
UC22F 0.033 0.051 0.018 0.012
UC22G 0.028 0.043 0.014 0.01

UC27C 0.03 0.044 0.016 0.011
UC27D 0.019 0.026 0.01 0.007
UC27E 0.016 0.025 0.009 0.008
UC27F 0.012 0.019 0.007 0.005
UC27G 0.01 0.013 0.006 0.004

UC27H 0.008 0.014 0.004 0.004
UCD27J 0.006 0.009 - ­UCD27K 0.006 0.009 - -

WINDING

311

SECTION RESISTANCES

WINDING

17

WINDING

05

WINDING

06

TRANSFORMER CONTROLLED GENERATOR

FRAME

SIZE

UC22C 0.059 0.078 0.082 0.055 0.059

UC22D 0.054 0.056 0.057 0.049 0.054

UC22E 0.041 0.05 0.053 0.038 0.041

UC22F 0.031 0.032 0.033 0.025 0.031

UC22G 0.022 0.026 0.028 0.021 0.022

SECTION RESISTANCES, 3 PHASE WINDINGS
380V 400V 415V 416V 460V
50Hz 50Hz 50Hz 60Hz 60Hz

Measure insulation resistance between sections and each
section to earth.

Unbalanced or incorrect winding resistances and/or low
insulation resistances to earth indicate rewinding of the stator
will be necessary. Refer to removal and replacement of
component assemblies subsection 7.5.3.

7.5.2 EXCITATION CONTROL TEST

7.5.2.1 AVR FUNCTION TEST

All types of AVR's can be tested with this procedure :

1. Remove exciter field leads X & XX (F1 & F2) from the
AVR terminals X & XX (F1 & F2).

2. Connect a 60W 240V household lamp to AVR terminals
X & XX (F1 & F2).

3. Set the AVR VOLTS control potentiometer fully
clockwise.

4. Connect a 12V, 1.0A DC supply to the exciter field leads
X & XX (F1 & F2) with X (F1) to the positive.

5. Start the generating set and run at rated speed.

6. Check that the generator output voltage is within +/-10%
of rated voltage.

Voltages at AVR terminals 7-8 on SX460 AVR or P2-P3 on
SX440 or SX421 AVR should be between 170 and 250 volts.
If the generator output voltage is correct but the voltage on 7­8 (or P2- P3) is low, check auxiliary leads and connections to
main terminals.

Voltages at P2, P3, P4 terminals on MX341 and MX321 hould
be as given in 7.5.1.

The lamp connected across X-XX should glow. In the case of
the SX460, SX440 and SX421 AVRs the lamp should glow
continuously. In the case of the MX341 and MX321 AVRs the
lamp should glow for approximately 8 secs. and then turn off.
Failure to turn off indicates faulty protection circuit and the
AVR should be replaced. Turning the "VOLTS" control
potentiometer fully anti-clockwise should turn off the lamp with
all AVR types.

Should the lamp fail to light the AVR is faulty and should be
replaced.

Important ! After this test turn VOLTS control

potentiometer fully anti-clockwise.

7.5.2.2 TRANSFORMER CONTROL

The transformer rectifier unit can only be checked by
continuity, resistance checks and insulation resistance
measurement.

Two phase transformer

Separate primary leads T1-T2-T3-T4 and secondary leads 10-

11. Examine windings for damage. Measure resistances

across T1-T3 and T2-T4. These will b e a low value but sh o ul d
be balanced. Check that there is resistance in the order of 8
ohms between leads 10 and 11. Check insulation resistance
of each winding section to earth and to other winding
sections.

Low insulation resistance, unbalanced primary resistance,
open or short circuited winding sections, indicates the
transformer unit should be replaced.

Three phase transformer

Separate primary leads T1-T2-T3 and secondary leads 6-7-8
and 10-11-12.

Examine windings for damage. Measure resistances across
T1-T2, T2-T3, T3-T1. These will be low but should be
balanced.

Check that resistances are balanced across 6-10, 7-11 and
8-12 and in the order of 18 ohms. Check insulation resistance
of each winding section to earth and to other winding
sections.

Low insulation resistance, unbalanced primary or secondary
winding resistances, open or short circuited winding sections
indicates the transformer unit should be replaced.

Rectifier units - Three phase and single phase

With the leads 10-11-12-X and XX removed from the rectifier
unit (lead 12 is not fitted on single phase transformer rectifier
units), check forward and reverse resistances between
terminals 10-X, 11-X, 12-X, 10-XX, 11-XX and 12-XX with a
multimeter.

A low forward resistance and high reverse resistance should
be read between each pair of terminals. If this is not the case
the unit is faulty and should be replaced.

7.5.3 REMOVAL AND REPLACEMENT OF
COMPONENT ASSEMBLIES

METRIC THREADS ARE USED THROUGHOUT

When lifting single bearing generators,
care is needed to ensure the generator

Caution !

frame is kept i n the horizontal plane. Th e
rotor is free to move in the frame and can
slide out if not correctly lifted. Incorrect
lifting can cause serious personal injury.

7.5.3.1 REMOVAL OF PERMANENT MAGNET
GENERATOR (PMG)

1. Remove 4 screws holding the sheet metal cylindrical
cover at the non-drive end and remove the cover.

2. Disconnect the in line connector from the PMG stator (3
wires go to this connector). It may be necessary to cut off
the nylon cable tie first.

3. Remove the 4 threaded pillars and clamps holding the
PMG stator onto the end bracket.

4. Tap the stator out of the 4 spigots and withdraw. The
highly magnetic rotor will attract the stator . Take care to
avoid contact which may damage the windings.

5. Remove the bolt in the centre from the rotor shaft and
pull off the rotor. It may be necessary to gently tap the
rotor away. Take care to tap gently and evenly - the rotor
has ceramicmagnets which are easily broken by shock.

Important ! The rotor assembly must not be dismantled.
Replacement is a reversal of the above procedure.

7.5.3.2 REMOVAL OF BEARINGS

Important ! Position the main rotor so that a full pole

face of the main rotor core is at the bottom
of the stator bore.

NOTE: Removal of the bearings may be effected either after
the rotor assembly has been removed OR more simply by
removal of endbracket(s). Refer to 7.5.3.3. and 7.5.3.4.

The bearings are pre-packed with grease and sealed for life.

The bearing(s) are a press fit and can be removed from the
shaft with 3 leg or 2 leg manual or hydraulic bearing pullers.

SINGLE BEARING ONLY : Before trying to pull off the
bearing remove the small circlip retaining it.

When fitting new bearings use a bearing heater to expand the
bearing before fitting to the shaft. Tap the bearing into place
ensuring that it contacts the shoulder on the shaft.

Refit the retaining circlip on single bearing generators.

7.5.3.3 REMOVAL OF ENDBRACKET AND EXCITER
STATOR

1. Remove exciter leads X+, XX- at the AVR.

2. Slacken 4 bolts (2 each side) situated on horizontal
centre line holding the terminal box.

3. Remove 2 bolts holding lifting lug, at the non-drive end,
and remove lug.

4. Remove sheet metal cylindrical cover (4 screws) over
PMG (if fitted) or Remove shallow sheet metal cover (4
screws) at the nondrive end.

5. Ease up the terminal box and support clear of the
nondrive endbracket.

6. Remove 6 bolts holding the non-drive endbracket to the
stator bar assembly. The endbracket is now ready for
removal.

7. Replace the lifting lug onto the endbracket and sling the
endbracket on a hoist to facilitate lifting.

8. Tap the endbracket around its perimeter to release from
the generator. The endbracket and exciter stator will
come away as a sing le assembly.

9. Remove the 4 screws holding the exciter stator to the
endbracket and gently tap the exciter stator to release it.
Replacement is a reversal of the above procedure.

7.5.3.4 REMOVAL OF THE ROTOR ASSEMBLY

Remove the permanent magnet generator. Refer to 7.5.3.1
or
Remove the four screws holding the sheet metal cover at the
non drive end and remove cover.

Caution !

With the PMG rotor removed single
bearing generator rotors are free to move
in the frame. Ensure frame is kept in the
horizontal plane when lifting.

TWO BEARING GENERATORS

1. Remove 2 screws holding the sheet metal cover around
the adaptor at the drive end and remove the cover.

2. Remove the bo lts holding the adaptor to the endbracket
at the drive end.

3. Tap off the adaptor. It may be preferred to sling the
adaptor first depending on its size and weight.

4. Remove the screens and louvres (if fitted) at each side
on the drive end.

Now ensure that the rotor is positioned with a full pole face at
the bottom centre line. This is to avoid damage to the bearing
exciter, or rotor winding, by limiting the possible rotor
downward movement to the air gap length.

5. Remove 6 bolts holding drive endbracket onto adaptor
ring DE. The boltheads face towards the non-drive end.
The top bolt passes through the centre of the lifting lug.

6. Tap the drive endbracket away from the adaptor ring DE
and withdraw the endbracket.

7. Ensure the rotor is supported at the drive end on a sling.

8. Tap the rotor from the non-drive end to push the bearing
clear of the endbracket and its position within an 'O' ring.

9. Continue to push the rotor out of the stator bore,

gradually working the sling along the rotor as it is
withdrawn, to ensure that it is fully supported all the
time.

SINGLE BEARING GENERATORS

1. Remove the screws, screens and louvres (if fitted) at
each side on drive end adaptor.

2. UCI224, UCI274, UCM224, UCM274, UCD274 Only
Remove 6 bolts holding the adaptor at the drive end. It
may be preferred to sling the adaptor on a hoist. The bolt
heads face towards the non-drive end. The top bolt
passes through the centre of the lifting lug.

2a. UCD224 Only Remove 6 bolts holding the adaptor at the
drive end. It may be preferred to sling the adaptor on a hoist.

3. UCI224, UCI274, UCM 224, UCM274, UCD274 Only Tap
the adaptor away from stator bar adaptor ring.

3a. UCD224 Only Tap the adaptor away from stator bar
assembly.

ALL SINGLE BEARING GENERATORS

4. Ensure the rotor is supported at drive end on a sling.

5. Tap the rotor from the non-drive end to push the bearing
clear of the endbracket and its position within an 'O' ring.

6. Continue to push the rotor out of the stator bore,
gradually working the sling along the rotor as it is
withdrawn, to ensure that it is fully supported at all times.

Replacement of rotor assemblies is a reversal of the
procedures above.

Before commencing re-assembly, components should be
checked for damage and bearing(s) examined for loss of
grease.

Fitting of new bearing(s) is recommended during major
overhaul.

Before replacement of a single bearing rotor assembly, check
that the drive discs are not damaged, cracked or showing
other signs of fatigue. Also check that the holes in the discs
for drive fixing screws are not elongated.

Damaged or worn components must be replaced.

When major components have been

Caution !

replaced, ensure that all covers and
guards are securely fitted, before the
generator is put into service.

7.6 RETURNING TO SERVICE

After rectification of any faults found, remove all test
connections and reconnect all control system leads. Restart
the set and adjust VOLTS control potentiometer on AVR
controlled generators by slowly turning clockwise until rated
voltage is obtained. Refit all terminal box covers/access
covers and reconnect heater supply.

Caution !

Failure to refit all guards, access covers
and terminal box covers can result in
personal injury of death.

SECTION 8

SPARES AND AFTER SALES SERVICE

8.1 RECOMMENDED SPARES

Service parts are conveniently packaged for easy
identification. Genuine parts may be recognised by the Nupart
name.

We recommend the following for Service and Maintenance. In
critical applications a set of these service spares should be
held with the generator.

AVR Controlled Generators

1. Diode Set (6 diodes with surge suppressor) RSK 2001

2. AVR SX440 E000 24030
AVR SX460 E000 24602
AVR SX421 E000 24210
AVR MX321 E000 23212
AVR MX341 E000 23410

3. Non drive end Bearing UC22 051 01032

UC27 051 01049

4. Drive end Bearing UC22 051 01044
UC27 051 01050

Transformer Controlled Generators (UC22 Only)

1. Diode Set (6 diodes with surge suppressor) RSK 2001

2. Diode Assembly E000 22006

3. Non drive end Bearing UC22 051 01032

4. Drive end Bearing UC22 051 01044

When ordering parts the machine serial number or machine
identity number and type should be quoted, together with the
part description. For location of these numbers see paragraph

1.3.
Orders and enquiries for parts should be addressed to:
STAMFORD & AvK Parts Department

Barnack Road
STAMFORD
Lincolnshire
PE9 2NB
ENGLAND

Telephone: [phone]
Fax: [phone]

Or any of our subsidiary companies listed on the back cover.

8.2 AFTER SALES SERVICE

A full technical advice and on-site service facility is availabl e
from our Service Department at Stamford or through our
Subsidiary Companies. A repair f acility is also available at our
Stamford Works.

TYPICAL SINGLE BEARING GENERATOR

Plate Ref. Description

1 Stator
2 Rotor
3 Exciter Rotor
4 Exciter Stator
5 N.D.E. Bracket
6 Cover N.D.E.
7 Bearing ‘O’ Ring N.D.E.
8 Bearing N.D.E.

9 Bearing Circlip N.D.E.
10 D.E. Bracket/Engine Adaptor
11 D.E. Screen
12 Coupling Disc
13 Couplimg Bolt
14 Foot
15 Frame Cover Bottom
16 Frame Cover Top
17 Air Inlet Cover
18 Terminal Box Lid
19 Endpanel D.E.
20 Endpanel N.D.E.
21 AVR
22 Side Panel
23 AVR Mounting Bracket
24 Main Rectifier Assembly - Forward
25 Main Rectifier Assembly - Reverse
26 Varistor
27 Diode - Forward Polarity
28 Diode - Reverse Polarity
29 Lifting Lug - D.E.
30 Lifting Lug - N.D.E.
31 Frame to Endbracket Adaptor Ring
32 Main Terminal Panel
33 Terminal Link
34 Edging Strip
35 Fan
36 Foot Mounting Spacer
37 Cap Screw
38 AVR Access Cover
39 AVR Anti-Vibration Mounting Assembly
40 Auxiliary Terminal Assembly

PARTS LIST

N.D.E. Non Driven End
D.E. Driven End
P.M.G. Permanent Magnet Generator
A.V.R. Automatic Voltage Regulator

Fig. 11.

TYPICAL SINGLE BEARING GENERATOR

TYPICAL TWO BEARING GENERATOR

Plate Ref. Description

1 Stator
2 Rotor
3 Exciter Rotor
4 Exciter Stator
5 N.D.E. Bracket
6 Cover N.D.E.
7 Bearing ‘O’ Ring N.D.E.
8 Bearing N.D.E.

9 Bearing Wave Washer.D.E.
10 D.E. Bracket
11 D.E. Screen
12 Bearing D.E.
13
14 Foot
15 Frame Cover Bottom
16 Frame Cover Top
17 Air Inlet Cover
18 Terminal Box Lid
19 Endpanel D.E.
20 Endpanel N.D.E.
21 AVR
22 Side Panel
23 AVR Mounting Bracket
24 Main Rectifier Assembly - Forward
25 Main Rectifier Assembly - Reverse
26 Varistor
27 Diode - Forward Polarity
28 Diode - Reverse Polarity
29 Lifting Lug - D.E.
30 Lifting Lug - N.D.E.
31 Frame to Endbracket Adaptor Ring
32 Main Terminal Panel
33 Terminal Link
34 Edging Strip
35 Fan
36 Foot Mounting Spacer
37 Cap Screw
38 AVR Access Cover
39 AVR Anti-Vibration Mounting Assembly
40 Auxiliary Terminal Assembly
41
42 PMG Exciter Rotor
43 PMG Exciter Stator
44 PMG Bolt
45 PMG Pillar
46 PMG Clamp
47 PMG Dowel

PARTS LIST

N.D.E. Non Driven End
D.E. Driven End
P.M.G. Permanent Magnet Generator
A.V.R. Automatic Voltage Regulator

Fig. 12.

TYPICAL TWO BEARING GENERATOR

TYPICAL TWO BEARING (SERIES 5) GENERATOR

Plate Ref.

1 Stator
2 Rotor
3 Exciter Rotor
4 Exciter Stator
5 N.D.E. Bracket
6 Cover N.D.E.
7 Bearing ‘O’ Ring N.D.E.
8 Bearing N.D.E.

9 Bearing Wave Washer N.D.E.
10 D.E. Bracket
11 D.E. Screen
12 Bearing D.E.
13
14 Foot
15 Frame Cover Bottom
16 Frame Cover Top
17 Air Inlet Cover
18 Terminal Box Lid
19 Endpanel D.E.
20 Endpanel N.D.E.
21 Series 5 Co ntrol Gear
22 Side Panel
23
24 Main Rectifier Assembly - Forward
25 Main Rectifier Assembly - Reverse
26 Varistor
27 Diode - Forward Polarity
28 Diode - Reverse Polarity
29 Lifting Lug - D.E.
30 Lifting Lug - N.D.E.
31 Frame to Endbracket Adaptor Ring
32 Main Terminal Panel
33 Terminal Link
34 Edging Strip
35 Fan
36 Foot Mounting Spacer
37 Cap Screw

Description

PARTS LIST

N.D.E. Non Driven End
D.E. Driven End

Fig. 13.

TYPICAL TWO BEARING (SERIES 5) GENERATOR

Fig. 14.

ROTATING RECTIFIER ASSEMBLY

A.C. GENERATOR WARRANTY

WARRANTY PERIOD
A.C. Generators

n respect of a.c. generators the Warranty Period is eighteen months from the

I
date when the goods have been notified as ready for despatch by N.I. or twelve
months from the date of first commissioning (whichever is the shorter period).

DEFECTS AFTER DELIVERY

We will make good by repair or, at our option, by the supply of a replacement,
any fault which under proper use appears in the goods within the period
specified on Clause 12, and is found on examination by us to be solely due to
defective mate r ial a n d w or kmanship; provid e d that the defective part is promptly
returned, carriage paid, with all identification numbers and marks intact, or our
works or, if appropriate to the Dealer who supplied the goods.

Any part repaired or replaced, under warranty, will be returned by N.I. free of
harge (via sea frei ght if outside the UK).

We shall not be liable for any expenses which may be incurred in removing or
replacing any part sent to us for inspection or in fitting any replacement supplied
by us. We shall be under no liability for defects in any goods which have not
been properly installed in accordance with N.I. recommended installation
practices as detailed in the publications 'N.I. Installation, Service and
Maintenance Manual' and 'N.I. Application Guidelines', or which have been
improperly stored or which have been repaired, adjusted or altered by any
person except ourselves or our authorised agents, or in any second-hand
goods, proprietary articles or goods not of our own manufacture although
supplied by us, such articles and goods being covered by the warranty (if any)
given by the separate manufacturers.

Any claim under this clause must contain fully particulars of the alleged defect,
the description of the goods, the date of purchase, and the name and address
of the Vendor, the Serial Number (as shown on the manufacturers identification
plate) or for Spares the order reference under which the goods were supplied.

Our judgement in all cases of claims shall be final and conclusive and the
claimant shall accept our decision on all questions as to defects and the
exchange of a part or parts.

Our liability shall be fully discharged by either repair or replacement as above,
and in any event shall not exceed the current list price of the defective goods.

Our liability under this clause shall be in lieu of any warranty or condition implied
by law as to the quality or fitness for any particular purpose of the goods, and
save as expressly provided in this clause we shall not be under any liability,
whether in contract, tort or otherwise, in respect of defects in goods delivered or
for any injury, damages or loss resulting from such defects or from any work
undone in connection therewith.

MACHINE SERIAL NUMBER

REGISTERED OFFICE AND ADDRESS:
BARNACK ROAD
STAMFORD
LINCOLNSHIRE
PE9 2NB ENGLAND

Telephone: [phone]
Fax: [phone]

SUBSIDIARY COMPANIES

1. AUSTRALIA : NEWAGE ENGINEERS PTY. LIMITED

PO Box 6027, Baulkham Hills Business Centre,
Baulkham Hills NSW 2153.
Telephone: Sydney (61) 2 9680 2299
Fax: [phone]

2. CHINA: WUXI NEWAGE ALTERNATORS LIMITED
Plot 49-A, Xiang Jiang Road
Wuxi High - Technical Industrial Dev. Zone
Wuxi, Jiangsu 214028
PR of China
Tel: [phone]
Fax: [phone]

3. GERMANY: NEWAGE E NGINEERS G. m. b .H.
Rotenbrückenweg 14, D-22113 Hamburg.
Telephone: Hamburg (49) 40 714 8750
Fax: [phone]

4. INDIA: C.G. NEWAGE ELECTRICAL LIMITED
C33 Midc, Ahmednagar 414111, Maharashtra.
Telephone: [phone]
Fax: [phone]

5. ITALY: NEWAGE ITALIA S.r.I.
Via Triboniano, 20156 Milan.
Telephone: Milan (39) 02 380 00714
Fax: [phone]

6. JAPAN: NEWAGE INTERNATIONAL JAPAN
8 - 5 - 302 Kashima
Hachioji-shi
Tokyo, 192-03
Telephone: [phone]
Fax: [phone]

7. NORWAY: NEWAGE NORGE A/S
Økern Naeringspark, Kabeigt. 5
Postboks 28, Økern, 0508 Oslo
Telephone: Oslo (47) 22 97 44 44
Fax: [phone]

8. SINGAPORE: NEWAGE ASIA PACIFIC PTE LIMITED
10 Toh Guan Road #05-03
TT International Tradepark
Singapore 608838
Telephone: Singapore (65) 794 3730
Fax: [phone]
Telex: RS 33404 NEWAGE

9. SPAIN: STAMFORD IBERICA S.A.
Ctra. Fuenlabrada-Humanes, km.2
Poligono Industrial "Los Linares"
C/Pico de Almanzor, 2
E-28970 HUMANES DE MADRID (Madrid)
Telephone: Madrid (34) 91 604 8987/8928
Fax: [phone]

10. U.S.A.: NEWAGE LIMITED
4700 Main St, N.E.
Fridley
Minnesota 55421
Telephone: [phone]
Fax: [phone]

© 2006

TD_UC MAN GB_10.06_