GE - General Electric AF-600 FP Design Guide
GE Consumer & Industrial
Electrical Distribution
AF-600 FP
TM
Fan and Pump Drive
Design Guide
Contents
AF-600 FP Design Guide
1 How to Read this Design Guide
Copyright, Limitation of Liability and Revision Rights 3
Approvals 4
Symbols 4
Abbreviations 5
Definitions 5
2 Introduction to AF-600 FP
Safety 11
CE Labelling 13
Aggressive Environments 14
Vibration and Shock 15
Application Examples 22
Control Structures 28
General Aspects of EMC 35
Galvanic Isolation (PELV) 39
PELV - Protective Extra Low Voltage 39
Earth Leakage Current 40
3
11
Extreme Running Conditions 40
3 AF-600 FP Selection
Options and Accessories 45
4 How to Install
Mechanical Dimensions 59
Lifting 64
Electrical Installation 66
Electrical Installation and Control Cables 67
Final Set-Up and Test 82
Additional Connections 84
Motor Insulation 86
Motor Bearing Currents 87
Installation of Misc. Connections 88
Safety 90
EMC-correct Installation 90
Residual Current Device 93
45
57
5 Application Examples
Start/Stop 95
Pulse Start/Stop 95
Potentiometer Reference 96
95
1
AF-600 FP Design Guide
Auto Tune 96
Logic Controller 96
Logic Controller Programming 97
LC Application Example 97
BASIC Cascade Controller 99
Pump Staging with Lead Pump Alternation 100
System Status and Operation 100
Fixed Variable Speed Pump Wiring Diagram 101
Lead Pump Alternation Wiring Diagram 102
Cascade Controller Wiring Diagram 103
Start/Stop Conditions 103
6 RS-485 Installation and Set-up
RS-485 Installation and Set-up 105
Drive Protocol Overview 107
Network Configuration 109
Drive Protocol Message Framing Structure 109
Examples 114
Modbus RTU Overview 116
Modbus RTU Message Framing Structure 117
How to Access Parameters 121
Examples 122
GE Drive Control Profile 128
7 General Specifications and Troubleshooting
Mains Supply Tables 133
General Specifications 145
Efficiency 149
Acoustic Noise 150
Peak Voltage on Motor 150
105
133
Special Conditions 155
Troubleshooting 157
Alarms and Warnings 157
Alarm Words 161
Warning Words 162
Extended Status Words 163
Fault Messages 164
Index
169
2
1 How to Read this Design Guide
AF-600 FP
Software version: 1.02
AF-600 FP Design Guide
1
This guide can be used with all AF-600 FP frequency converters with
software version 1.02 or later.
The actual software version number can be read from
par. ID-43 Software Version.
1.1.1 Copyright, Limitation of Liability and Revision Rights
This publication contains information proprietary to GE. By accepting and using this manual the user agrees that the information contained herein will be used
solely for operating equipment from GE or equipment from other vendors provided that such equipment is intended for communication with GE equipment over
a serial communication link. This publication is protected under the Copyright laws of Denmark and most other countries.
GE does not warrant that a software program produced according to the guidelines provided in this manual will function properly in every physical, hardware or
software environment.
Although GE has tested and reviewed the documentation within this manual, GE makes no warranty or representation, neither expressed nor implied, with respect
to this documentation, including its quality, performance, or fitness for a particular purpose.
In no event shall GE be liable for direct, indirect, special, incidental, or consequential damages arising out of the use, or the inability to use information contained
in this manual, even if advised of the possibility of such damages. In particular, GE is not responsible for any costs, including but not limited to those incurred as
a result of lost profits or revenue, loss or damage of equipment, loss of computer programs, loss of data, the costs to substitute these, or any claims by third
parties.
GE reserves the right to revise this publication at any time and to make changes to its contents without prior notice or any obligation to notify former or present
users of such revisions or changes.
3
1.1.2 Available Literature for AF-600 FP
AF-600 FP Design Guide
1
- Operating Instructions provide the necessary information for getting the drive up and running.
- Design Guide entails all technical information about the drive and customer design and applications.
- Programming Guide provides information on how to program and includes complete parameter descriptions.
GE technical literature is available in print from your local GE Sales Office or online at: www.geelectrical.com/drives
- AF-600 FP Built-in network manuals are available separately.
1.1.3 Approvals
1.1.4 Symbols
Symbols used in this guide.
NB!
Indicates something to be noted by the reader.
Indicates a general warning.
Indicates a high-voltage warning.
Indicates default setting
*
4
1.1.5 Abbreviations
AF-600 FP Design Guide
Alternating current AC
American wire gauge AWG
Ampere/AMP A
Current limit I
Degrees Celsius °C
Direct current DC
Drive Control Tool PC Software DCT 10
Drive Dependent D-TYPE
Electro Magnetic Compatibility EMC
Electronic Thermal Overload Elec. OL
Gram g
Hertz Hz
Kilohertz kHz
Meter m
Millihenry Inductance mH
Milliampere mA
Millisecond ms
Minute min
Nanofarad nF
Newton Meters Nm
Nominal motor current I
Nominal motor frequency f
Nominal motor power P
Nominal motor voltage U
Parameter par.
Protective Extra Low Voltage PELV
Printed Circuit Board PCB
Rated Inverter Output Current I
Revolutions Per Minute RPM
Regenerative terminals Regen
Second s
Synchronous Motor Speed n
Torque limit T
Volts V
LIM
M,N
M,N
M,N
M,N
INV
s
LIM
1
1.1.6 Definitions
Drive:
I
DRIVE,MAX
The maximum output current.
I
DRIVE,N
The rated output current supplied by the frequency converter.
U
DRIVE, MAX
The maximum output voltage.
Input:
Control command
You can start and stop the connected motor by means of keypad and the
digital inputs.
Functions are divided into two groups.
Functions in group 1 have higher priority than functions in group 2.
Group 1
Group 2
Reset, Coasting stop, Reset and Coasting stop, Quick-stop, DC braking, Stop and the "Off" key.
Start, Pulse start, Reversing, Start reversing, Jog and Freeze output
5
Motor:
f
1
JOG
The motor frequency when the jog function is activated (via digital terminals).
f
M
The motor frequency.
f
MAX
The maximum motor frequency.
f
MIN
The minimum motor frequency.
f
M,N
The rated motor frequency (nameplate data).
I
M
The motor current.
I
M,N
The rated motor current (nameplate data).
AF-600 FP Design Guide
n
M,N
The rated motor speed (nameplate data).
P
M,N
The rated motor power (nameplate data).
T
M,N
The rated torque (motor).
U
M
The instantaneous motor voltage.
U
M,N
The rated motor voltage (nameplate data).
Break-away torque
DRIVE
The efficiency of the frequency converter is defined as the ratio between the power output and the power input.
6
Start-disable command
A stop command belonging to the group 1 control commands - see this group.
AF-600 FP Design Guide
Stop command
See Control commands.
References:
Analog Reference
A signal transmitted to the analog inputs 53 or 54, can be voltage or current.
Bus Reference
A signal transmitted to the serial communication port (drive port).
Preset Reference
A defined preset reference to be set from -100% to +100% of the reference range. Selection of eight preset references via the digital terminals.
Pulse Reference
A pulse frequency signal transmitted to the digital inputs (terminal 29 or 33).
Ref
MAX
Determines the relationship between the reference input at 100% full scale value (typically 10 V, 20mA) and the resulting reference. The maximum reference value
set in par. F-53 Maximum Reference.
Ref
MIN
Determines the relationship between the reference input at 0% value (typically 0V, 0mA, 4mA) and the resulting reference. The minimum reference value set in
par. F-52 Minimum Reference
1
Miscellaneous:
Advanced Vecter Control
If compared with standard voltage/frequency ratio control, Advanced Vecter Control improves the dynamics and the stability, both when the speed reference is
changed and in relation to the load torque.
Analog Inputs
The analog inputs are used for controlling various functions of the frequency converter.
There are two types of analog inputs:
Current input, 0-20 mA and 4-20 mA
Voltage input, 0-10 V DC.
Analog Outputs
The analog outputs can supply a signal of 0-20 mA, 4-20 mA, or a digital signal.
Auto Tune
Auto Tune algorithm determines the electrical parameters for the connected motor at standstill.
CT Characteristics
Constant torque characteristics used for screw and scroll refrigeration compressors.
Digital Inputs
The digital inputs can be used for controlling various functions of the frequency converter.
Digital Outputs
The frequency converter features two Solid State outputs that can supply a 24 V DC (max. 40 mA) signal.
7
AF-600 FP Design Guide
DSP
Digital Signal Processor.
1
Relay Outputs:
The frequency converter features two programmable Relay Outputs.
Electronic Thermal Overload
Electronic Thermal Overload is a thermal load calculation based on present load and time. Its purpose is to estimate the motor temperature.
Initialising
If initialising is carried out (par. H-03 Restore Factory Settings), the programmable parameters of the frequency converter return to their default settings.
Intermittent Duty Cycle
An intermittent duty rating refers to a sequence of duty cycles. Each cycle consists of an on-load and an off-load period. The operation can be either periodic duty
or none-periodic duty.
keypad
The keypad makes up a complete interface for control and programming of the frequency converter. The is detachable and can be installed up to 3 metres from
the frequency converter, i.e. in a front panel by means of the installation kit option.
lsb
Least significant bit.
MCM
2
Short for Mille Circular Mil, an American measuring unit for cable cross-section. 1 MCM ≡ 0.5067 mm
msb
Most significant bit.
On-line/Off-line Parameters
Changes to on-line parameters are activated immediately after the data value is changed. Changes to off-line parameters are not activated until you enter [OK]
on the keypad.
PID Controller
The PID controller maintains the desired speed, pressure, temperature, etc. by adjusting the output frequency to match the varying load.
RCD
Residual Current Device.
Set-up
You can save parameter settings in four Set-ups. Change between the four parameter Set-ups and edit one Set-up, while another Set-up is active.
SFAVM
Switching pattern called
Slip Compensation
The frequency converter compensates for the motor slip by giving the frequency a supplement that follows the measured motor load keeping the motor speed
almost constant.
Stator Flux oriented Asynchronous V ector M odulation (par. F-37 Adv. Switching Pattern).
.
Logic Controller (LC)
The LC is a sequence of user defined actions executed when the associated user defined events are evaluated as true by the LC.
Thermistor:
A temperature-dependent resistor placed where the temperature is to be monitored (frequency converter or motor).
8
AF-600 FP Design Guide
Trip
A state entered in fault situations, e.g. if the frequency converter is subject to an over-temperature or when the frequency converter is protecting the motor,
process or mechanism. Restart is prevented until the cause of the fault has disappeared and the trip state is cancelled by activating reset or, in some cases, by
being programmed to reset automatically. Trip may not be used for personal safety.
Trip Locked
A state entered in fault situations when the frequency converter is protecting itself and requiring physical intervention, e.g. if the frequency converter is subject
to a short circuit on the output. A locked trip can only be cancelled by cu tting off mains, removing the cause of the fault, and reconnecting th e frequency converter.
Restart is prevented until the trip state is cancelled by activating reset or, in some cases, by being programmed to reset automatically. Trip locked may not be
used for personal safety.
VT Characteristics
Variable torque characteristics used for pumps and fans.
60° AVM
Switching pattern called 60°
1.1.7 Power Factor
Asynchronous Vector Modulation (See par. F-37 Adv. Switching Pattern).
1
The power factor is the relation between I1 and I
The power factor for 3-phase control:
The power factor indicates to which extent the frequency converter imposes
a load on the mains supply.
The lower the power factor, the higher the I
In addition, a high power factor indicates that the different harmonic currents are low.
The frequency converters' built-in DC coils produce a high power factor, which minimizes the imposed load on the mains supply.
.
RMS
for the same kW performance.
RMS
Power factor
I
cos
×
1
=
I
RMS
I
RMS
2
=
I
1
=
ϕ1
+
3 × U ×
3 × U ×
I
1
=
I
RMS
2
+
I
I
5
since cos
2
+ . . +
7
I
1 ×
COS
I
RMS
ϕ1=1
2
I
n
ϕ
9
2
AF-600 FP Design Guide
10
2 Introduction to AF-600 FP
2.1 Safety
AF-600 FP Design Guide
2.1.1 Safety Note
The voltage of the frequency converter is dangerous whenever connected to mains. Incorrect installation of the motor, frequency converter
or network may cause death, serious personal injury or damage to the equipment. Consequently, the instructions in this manual, as well as
national and local rules and safety regulations, must be complied with.
Safety Regulations
1. The frequency converter must be disconnected from mains if repair work is to be carried out. Check that the mains supply has been disconnected and
that the necessary time has passed before removing motor and mains plugs.
2. The [STOP/RESET] key on the keypad of the frequency converter does not disconnect the equipment from mains and is thus not to be used as a safety
switch.
3. Correct protective earthing of the equipment must be established, the user must be protected against supply voltage, and the motor must be protected
against overload in accordance with applicable national and local regulations.
4. The earth leakage currents are higher than 3.5 mA.
5. Protection against motor overload is set by par. F-10 Electronic Overload . If this function is desired, set par. F-10 Electronic Overload to data value
[Electronic Thermal Overload trip] (default value) or data value [Electronic Thermal Overload warning]. Note: The function is initialized at 1.16 x rated
motor current and rated motor frequency. For the North American market: The Electronic Thermal Overload functions provide class 20 motor overload
protection in accordance with NEC.
6. Do not remove the plugs for the motor and mains supply while the frequency converter is connected to mains. Check that the mains supply has been
disconnected and that the necessary time has passed before removing motor and mains plugs.
7. Please note that the frequency converter has more voltage inputs than L1, L2 and L3, when load sharing (linking of DC intermediate circuit) and external
24 V DC have been installed. Check that all voltage inputs have been disconnected and that the necessary time has passed before commencing repair
work.
Installation at high altitudes
Installation at high altitude:
380 - 480 V, unit sizes 1x, 2x and 3x: At altitudes above 2 km, please contact GE regarding PELV.
380 - 480 V, unit sizes 4x, 5x and 6x: At altitudes above 3 km, please contact GE regarding PELV.
525 - 690 V: At altitudes above 2 km, please contact GE regarding PELV.
2
Warning against Unintended Start
1. The motor can be brought to a stop by means of digital commands, bus commands, references or a local stop, while the frequency converter is connected
to mains. If personal safety considerations make it necessary to ensure that no unintended start occurs, these stop functions are not sufficient.
2. While parameters are being changed, the motor may start. Consequently, the stop key [STOP/RESET] must always be activated; following which data
can be modified.
3. A motor that has been stopped may start if faults occur in the electronics of the frequency converter, or if a temporary overload or a fault in the supply
mains or the motor connection ceases.
Warning:
Touching the electrical parts may be fatal - even after the equipment has been disconnected from mains.
Also make sure that other voltage inputs have been disconnected, such as external 24 V DC, load sharing (linkage of DC intermediate circuit), as well as the motor
connection for kinetic back up. Refer to the Operating Instructions for further safety guidelines.
11
2
AF-600 FP Design Guide
2.1.2 Caution
The frequency converter DC link capacitors remain charged after power has been disconnected. To avoid an electrical shock hazard, disconnect
the frequency converter from the mains before carrying out maintenance. Wait at least as follows before doing service on the frequency
converter:
Voltage (V) Min. Waiting Time (Minutes)
4 15 20 30 40
200 - 240 1.1 - 3.7 kW 5.5 - 45 kW
380 - 480 1.1 - 7.5 kW 11 - 90 kW 110 - 250 kW 315 - 1000 kW
525 - 600 1.1 - 7.5 kW 11 - 90 kW
525 - 690 110 - 400 kW 450 - 1200 kW
Be aware that there may be high voltage on the DC link even when the LEDs are turned off.
12
AF-600 FP Design Guide
2.1.3 Disposal Instruction
Equipment containing electrical components may not be disposed of together with domestic waste.
It must be separately collected with electrical and electronic waste according to local and currently
valid legislation.
2.2 CE Labelling
2.2.1 CE Conformity and Labelling
What is CE Conformity and Labelling?
The purpose of CE labelling is to avoid technical trade obstacles within EFTA and the EU. The EU has introduced the CE label as a simple way of showing whether
a product complies with the relevant EU directives. The CE label says nothing about the specifications or quality of the product. Frequency converters are regulated
by three EU directives:
The machinery directive (98/37/EEC)
All machines with critical moving parts are covered by the machinery directive of January 1, 1995. Since a frequency converter is largely electrical, it does not fall
under the machinery directive. However, if a frequency converter is supplied for use in a machine, we provide information on safety aspects relating to the
frequency converter. We do this by means of a manufacturer's declaration.
The low-voltage directive (73/23/EEC)
Frequency converters must be CE labelled in accordance with the low-voltage directive of January 1, 1997. The directive applies to all electrical equipment and
appliances used in the 50 - 1000 V AC and the 75 - 1500 V DC voltage ranges. GE CE-labels in accordance with the directive and issues a declaration of conformity
upon request.
The EMC directive (89/336/EEC)
EMC is short for electromagnetic compatibility. The presence of electromagnetic compatibility means that the mutual interference between different components/
appliances does not affect the way the appliances work.
The EMC directive came into effect January 1, 1996. GE CE-labels in accordance with the directive and issues a declaration of conformity upon request. To carry
out EMC-correct installation, see the instructions in this Design Guide. In addition, we specify which standards our products comply with. We offer the filters
presented in the specifications and provide other types of assistance to ensure the optimum EMC result.
2
The frequency converter is most often used by professionals of the trade as a complex component forming part of a larger appliance, system or installation. It
must be noted that the responsibility for the final EMC properties of the appliance, system or installation rests with the installer.
2.2.2 What Is Covered
The EU "Guidelines on the Application of Council Directive 89/336/EEC" outline three typical situations of using a frequency converter. See below for EMC coverage
and CE labelling.
1. The frequency converter is sold directly to the end-consumer. The frequency converter is for example sold to a DIY market. The end-consumer is a
layman. He installs the frequency converter himself for use with a hobby machine, a kitchen appliance, etc. For such applications, the frequency converter
must be CE labelled in accordance with the EMC directive.
2. The frequency converter is sold for installation in a plant. The plant is built up by professionals of the trade. It could be a production plant or a heating/
ventilation plant designed and installed by professionals of the trade. Neither the frequency converter nor the finished plant has to b e CE lab elled und er
the EMC directive. However, the unit must comply with the basic EMC requirements of the directive. This is ensured by using components, appliances,
and systems that are CE labelled under the EMC directive.
3. The frequency converter is sold as part of a complete system. The system is being marketed as complete and could e.g. be an air-conditioning system.
The complete system must be CE labelled in accordance with the EMC directive. The manufacturer can ensure CE labelling under the EMC directive either
by using CE labelled components or by testing the EMC of the system. If he chooses to use only CE labelled components, he does not have to test the
entire system.
13
AF-600 FP Design Guide
2.2.3 GE Frequency Converter and CE Labelling
CE labelling is a positive feature when used for its original purpose, i.e. to facilitate trade within the EU and EFTA.
However, CE labelling may cover many different specifications. Thus, you have to check what a given CE label specifically covers.
2
The covered specifications can be very different and a CE label may therefore give the installer a false feeling of security when using a frequency converter as a
component in a system or an appliance.
GE CE labels the frequency converters in accordance with the low-voltage directive. This means that if the frequency converter is installed correctly, we guarantee
compliance with the low-voltage directive. GE issuesWe issue a declaration of conformity that confirms our CE labelling in accordance with the low-voltage
directive.
The CE label also applies to the EMC directive provided that the instructions for EMC-correct installation and filtering are followed. On this basis, a declaration of
conformity in accordance with the EMC directive is issued.
The Design Guide offers detailed instructions for installation to ensure EMC-correct installation. Furthermore, GE specifies which our different products comply
with.
GE provides other types of assistance that can help you obtain the best EMC result.
2.2.4 Compliance with EMC Directive 89/336/EEC
As mentioned, the frequency converter is mostly used by professionals of the trade as a complex component forming part of a larger appliance, system, or
installation. It must be noted that the responsibility for the final EMC properties of the appliance, system or installation rests with the installer. As an aid to the
installer, GE has prepared EMC installation guidelines for the Power Drive system. The standards and test levels stated for Power Drive systems are complied with,
provided that the EMC-correct instructions for installation are followed, see the section EMC Immunity.
The frequency converter has been designed to meet the IEC/EN 60068-2-3 standard, EN 50178 pkt. 9.4.2.2 at 50°C.
2.4.1 Aggressive Environments
A frequency converter contains a large number of mechanical and electronic components. All are to some extent vulnerable to environmental effects.
The frequency converter should not be installed in environments with airborne liquids, particles, or gases capable of affecting and damaging
the electronic components. Failure to take the necessary protective measures increases the risk of stoppages, thus reducing the life of the
frequency converter.
Liquids can be carried through the air and condense in the frequency converter and may cause corrosion of components and metal parts. Steam, oil, and salt
water may cause corrosion of components and metal parts. In such environments, use equipment with Unit Size rating IP 54/55. As an extra protection, coated
printed circuit boards can be ordered as an option.
Airborne
Particles such as dust may cause mechanical, electrical, or thermal failure in the frequency converter. A typical indicator of excessive levels of airborne
particles is dust particles around the frequency converter fan. In very dusty environments, use equipment with Unit Size rating IP 54/55 or a cabinet for IP 00/IP
20/TYPE 1 equipment.
In environments with high temperatures and humidity,
frequency converter components.
Such chemical reactions will rapidly affect and damage the electronic components. In such environments, mount the equipment in a cabinet with fresh air
ventilation, keeping aggressive gases away from the frequency converter.
An extra protection in such areas is a coating of the printed circuit boards, which can be ordered as an option.
corrosive gases such as sulphur, nitrogen, and chlorine compounds will cause chemical processes on the
14
AF-600 FP Design Guide
NB!
Mounting frequency converters in aggressive environments increases the risk of stoppages and considerably reduces the life of the converter.
Before installing the frequency converter, check the ambient air for liquids, particles, and gases. This is done by observing existing installations in this environment.
Typical indicators of harmful airborne liquids are water or oil on metal parts, or corrosion of metal parts.
Excessive dust particle levels are often found on installation cabinets and existing electrical installations. One in dicator of aggressive airborne gases is blackening
of copper rails and cable ends on existing installations.
NB!
Unit Sizes 4x and 5x have a stainless steel back-channel option to provide additional protection in aggressive environments. Proper ventilation is still required
for the internal components of the drive. Contact GE for additional information.
2.5 Vibration and Shock
The frequency converter has been tested according to the procedure based on the shown standards:
The frequency converter complies with requirements that exist for units mounted on the walls and floors of production premises, as well as in panels bolted to
walls or floors.
2
IEC/EN 60068-2-6: Vibration (sinusoidal) - 1970
IEC/EN 60068-2-64: Vibration, broad-band random
2.7 Advantages
2.7.1 Why use a Frequency Converter for Controlling Fans and Pumps?
A frequency converter takes advantage of the fact that centrifugal fans and pumps follow the laws of proportionality for such fans and pumps. For further
information see the text The Laws of Proportionality.
2.7.2 The Clear Advantage - Energy Savings
The very clear advantage of using a frequency converter for controlling the speed of fans or pumps lies in the electricity savings.
When comparing with alternative control systems and technologies, a frequency converter is the optimum energy control system for controlling fan and pump
systems.
Illustration 2.1: The graph is showing fan curves (A, B and C) for
reduced fan volumes.
15
2
AF-600 FP Design Guide
Illustration 2.2: When using a freq uency converter to reduce fan
capacity to 60% - more than 50% energy savings may be ob-
tained in typical applications.
2.7.3 Example of Energy Savings
As can be seen from the figure (the laws of proportionality), the flow is controlled by changing the RPM. By reducing the speed only 20% from the rated speed,
the flow is also reduced by 20%. This is because the flow is directly proportional to the RPM. The consumption of electricity, however, is reduced by 50%.
If the system in question only needs to be able to supply a flow that corresponds to 100% a few days in a year, while the average is below 80% of the rated flow
for the remainder of the year, the amount of energy saved is even more than 50%.
The laws of proportionality
The figure below describes the dependence of flow, pressure and power consumption on RPM.
Q = Flow P = Power
Q1 = Rated flow P1 = Rated power
= Reduced flow P2 = Reduced power
Q
2
H = Pressure n = Speed regulation
H1 = Rated pressure n1 = Rated speed
= Reduced pressure n2 = Reduced speed
H
2
16
Q
n
1
Flow
:
Pressure
Power
:
Q
:
2
P
P
=
H
H
1
2
1
2
=
1
n
2
=
n
(
n
n
2
1
(
)
n
2
3
1
)
2
2.7.4 Comparison of Energy Savings
The GE frequency converter solution offers major savings compared with
traditional energy saving solutions. This is because the frequency converter
is able to control fan speed according to thermal load on the system and the
fact that the frequency converter has a build-in facility that enables the fre-
quency converter to function as a Building Management System, BMS.
AF-600 FP Design Guide
2
The graph below illustrates typical energy savings obtainable with 3 well-
known solutions when fan volume is reduced to i.e. 60%.
As the graph shows, more than 50% energy savings can be achieved in typical
applications.
Illustration 2.3: The three common energy saving systems.
17
2
AF-600 FP Design Guide
Illustration 2.4: Discharge dampers reduce power consumption somewhat. Inlet Guide Vans offer a 40% reduction but are expensive to install. The
GEfrequency converter solution reduces energy consumption with more than 50% and is easy to install.
2.7.5 Example with Varying Flow over 1 Year
The example below is calculated on the basis of pump characteristics ob-
tained from a pump datasheet.
The result obtained shows energy savings in excess of 50% at the given flow
distribution over a year. The pay back period depends on the price per kwh
and price of frequency converter. In this example it is less than a year when
compared with valves and constant speed.
Energy savings
P
shaft=Pshaft output
Flow distribution over 1 year
18
AF-600 FP Design Guide
2
m3/h
Distribution Valve regulation Frequency converter control
% Hours Power Consumption Power Consumption
A1 - B
350 5 438 42,5 18.615 42,5 18.615
300 15 1314 38,5 50.589 29,0 38.106
250 20 1752 35,0 61.320 18,5 32.412
200 20 1752 31,5 55.188 11,5 20.148
150 20 1752 28,0 49.056 6,5 11.388
100 20 1752 23,0 40.296 3,5 6.132
Σ 100 8760 275.064 26.801
1
kWh A1 - C
1
kWh
2.7.6 Better Control
If a frequency converter is used for controlling the flow or pressure of a system, improved control is obtained.
A frequency converter can vary the speed of the fan or pump, thereby obtaining variable control of flow and pressure.
Furthermore, a frequency converter can quickly adapt the speed of the fan or pump to new flow or pressure conditions in the system.
Simple control of process (Flow, Level or Pressure) utilizing the built in PID control.
2.7.7 Cos φ Compensation
Generally speaking, a frequency converter with a cos of 1 provides power factor correction for the cos of the motor, which means that there is no need to
make allowance for the cos of the motor when sizing the power factor correction unit.
19
AF-600 FP Design Guide
2.7.8 Star/Delta Starter or Soft-starter not Required
When larger motors are started, it is necessary in many countries to use equipment that limits the start-up current. In more traditional systems, a star/delta starter
or soft-starter is widely used. Such motor starters are not required if a frequency converter is used.
As illustrated in the figure below, a frequency converter does not consume more than rated current.
2
1 = AF-600 FP
2 = Star/delta starter
3 = Soft-starter
4 = Start directly on mains
2.7.9 Using a Frequency Converter Saves Money
The example on the following page shows that a lot of equipment is not required when a frequency converter is used. It is possible to calculate the cost of installing
the two different systems. In the example on the following page, the two systems can be established at roughly the same price.
2.7.10 Without a Frequency Converter
The figure shows a fan system made in the traditional way.
D.D.C. = Direct Digital Control E.M.S. = Energy Management system
V.A.V. = Variable Air Volume
Sensor P = Pressure Sensor T = Temperature
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2.7.11 With a Frequency Converter
The figure shows a fan system controlled by frequency converters.
AF-600 FP Design Guide
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AF-600 FP Design Guide
2.7.12 Application Examples
The next few pages give typical examples of applications within HVAC.
2.7.13 Variable Air Volume
2
VAV or Variable Air Volume systems, are used to control both the ventilation and temperature to satisfy the requirements of a building. Central VAV systems are
considered to be the most energy efficient method to air condition buildings. By designing central systems instead of distributed systems, a greater efficiency can
be obtained.
The efficiency comes from utilizing larger fans and larger chillers which have much higher efficiencies than small motors and distributed air-cooled chille rs. Savings
are also seen from the decreased maintenance requirements.
2.7.14 The AF-600 FP Solution
While dampers and IGVs work to maintain a constant pressure in the ductwork, a frequency converter solution saves much more energy and reduces the complexity
of the installation. Instead of creating an artificial pressure drop or causing a decrease in fan efficiency, the frequency converter decreases the speed of the fan
to provide the flow and pressure required by the system.
Centrifugal devices such as fans behave according to the centrifugal laws. This means the fans decrease the pressure and flow they produce as their speed is
reduced. Their power consumption is thereby significantly reduced.
The return fan is frequently controlled to maintain a fixed difference in airflow between the supply and return. The advanced PID controller of the HVAC frequency
converter can be used to eliminate the need for additional controllers.
Pressu re
Cooling coil
D1
D2
D3
Heating coil
Fil t e r
sig n al
Su pp l y f an
3
Ret ur n f a n
VAV b oxe s
Pressu re
transmitter
Flo w
Flo w
3
vav2.10
T
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e
AF-600 FP Design Guide
2.7.15 Constant Air Volume
CAV, or Constant Air Volume systems are central ventilation systems usually used to supply large common zones with the minimum amounts of fresh tempered
air. They preceded VAV systems and therefore are found in older multi-zoned commercial buildings as well. These systems preheat amounts of fresh air utilizing
Air Handling Units (AHUs) with a heating coil, and many are also used to air condition buildings and have a cooling coil. Fan coil units are frequently used to assist
in the heating and cooling requirements in the individual zones.
2.7.16 The AF-600 FP Solution
With a frequency converter, significant energy savings can be obtained while maintaining decent control of the building. Temperature sensors or CO2 sensors
can be used as feedback signals to frequency converters. Whether controlling temperature, air quality, or both, a CAV system can be controlled to operate based
on actual building conditions. As the number of people in the controlled area decreases, the need for fresh air decreases. The CO
decreases the supply fans speed. The return fan modulates to maintain a static pressure setpoint or fixed difference between the supply and return air flows.
With temperature control, especially used in air conditioning systems, as the outside temperature varies as well as the number of people in the controlled zone
changes, different cooling requirements exist. As the temperature decreases below the set-point, the supply fan can decrease its speed. The return fan modulates
to maintain a static pressure set-point. By decreasing the air flow, energy used to heat or cool the fresh air is also reduced, adding further savings.
Several features of the GE dedicate d frequency converter can be utilized to improve the performance of your CAV system. One concern of controllin g a ventilation
system is poor air quality. The programmable minimum frequency can be set to maintain a minimum amount of supply air regardless of the feedback or reference
signal. The frequency converter also includes a 3-zone, 3 setpoint PID controller which allows monitoring both temperature and air quality. Even if the temperature
requirement is satisfied, the frequency converter will maintain enough supply air to satisfy the air quality sensor. The controller is capable of monitoring and
comparing two feedback signals to control the return fan by maintaining a fixed differential air flow between the supply and return ducts as well.
sensor detects lower levels and
2
2
Tem p er at u re
Cooling coil
D1
D2
D3
Heating coil
Fi lt er
sig n al
Su p pl y f an
Pressu r e
sig n al
Re t ur n f a n
Tem p er at u r
transmitter
Pressu r e
transmitter
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AF-600 FP Design Guide
2.7.17 Cooling Tower Fan
Cooling Tower Fans are used to cool condenser water in water cooled chiller systems. Water cooled chillers provide the most efficient means of creating chilled
water. They are as much as 20% more efficient than air cooled chillers. Depending on climate, cooling towers are often the most energy efficient method of cooling
the condenser water from chillers.
They cool the condenser water by evaporation.
2
The condenser water is sprayed into the cooling tower onto the cooling towers “fill” to increase its surface area. The tower fan blows air through the fill and sprayed
water to aid in the evaporation. Evaporation removes energy from the water dropping its temperature. The cooled water collects in the cooling towers basin
where it is pumped back into the chillers condenser and the cycle is repeated.
2.7.18 The AF-600 FP solution
With a frequency converter, the cooling towers fans can be controlled to the required speed to maintain the condenser water temperature. The frequency
converters can also be used to turn the fan on and off as needed.
Several features of the GE dedicated frequency converter, the HVAC frequency converter can be utilized to improve the performance of your cooling tower fans
application. As the cooling tower fans drop below a certain speed, the effect the fan has on cooling the water becomes small. Also, when utilizing a gear-box to
frequency control the tower fan, a minimum speed of 40-50% may be required.
The customer programmabl e minimum frequency setting is available to main tain this minimum frequency even as the feedback or speed reference calls for lower
speeds.
Also as a standard feature, you can program the frequency converter to enter a “sleep” mode and stop the fan until a higher speed is required. Additionally, some
cooling tower fans have undesireable frequencies that may cause vibrations. These frequencies can easily be avoided by programming the bypass frequency
ranges in the frequency converter.
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AF-600 FP Design Guide
2.7.19 Condenser Pumps
Condenser Water pumps are primarily used to circulate water through the condenser section of water cooled chillers and their associated cooling tower. The
condenser water absorbs the heat from the chiller's condenser section and releases it into the atmosphere in the cooling tower. These systems are used to provide
the most efficient means of creating chilled water, they are as much as 20% more efficient than air cooled chillers.
2.7.20 The AF-600 FP solution
Frequency converters can be added to condenser water pumps instead of balancing the pumps with a throttling valve or trimming the pump impeller.
Using a frequency converter instead of a throttling valve simply saves the energy that would have been absorbed by the valve. This can amount to savings of
15-20% or more. Trimming the pump impeller is irreversible, thus if the conditions change and higher flow is required the impeller must be replaced.
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AF-600 FP Design Guide
2.7.21 Primary Pumps
Primary pumps in a primary/secondary pumping system can be used to maintain a constant flow through devices that encounter operation or control difficulties
when exposed to variable flow. The primary/ secondary pumping technique decouples the “primary” production loop from the “secondary” distribution loop. This
allows devices such as chillers to obtain constant design flow and operate properly while allowing the rest of the system to vary in flow.
2
As the evaporator flow rate decreases in a chiller, the chilled water begins to become over-chilled. As this happens, the chiller attempts to decrease its cooling
capacity. If the flow rate drops far enough, or too quickly, the chiller cannot shed its load sufficiently and the chiller’s low evaporator temperature safety trips the
chiller requiring a manual reset. This situation is common in large installations especially when two or more chillers in parallel are installed if primary/ secondary
pumping is not utilized.
2.7.22 The AF-600 FP Solution
Depending on the size of the system and the size of the primary loop, the energy consumption of the primary loop can become substantial.
A frequency converter can be added to the primary system, to replace the throttling valve and/or trimming of the impellers, leading to reduced operating expenses.
Two control methods are common:
The first method uses a flow meter. Because the desired flow rate is known and is constant, a flow meter installed at the discharge of each chiller, can be used
to control the pump directly. Using the built-in PID controller, the frequency converter will always maintain the appropriate flow rate, even compensating for the
changing resistance in the primary piping loop as chillers and their pumps are staged on and off.
The other method is local speed determination. The operator simply decreases the output frequency until the design flow rate is achieved.
Using a frequency converter to decrease the pump speed is very similar to trimming the pump impelle r, except it doesn’t require any labor and the pump efficiency
remains higher. The balancing contractor simply decreases the speed of the pump until the proper flow rate is achieved and leaves the speed fixed. The pump
will operate at this speed any time the chiller is staged on. Because the primary loop doesn’t have control valves or oth er devices that can cause the system curve
to change and the variance due to staging pumps and chillers on and off is usually small, this fixed speed will remain appropriate. In the event the flow rate needs
to be increased later in the systems life, the frequency converter can simply increase the pump speed instead of requiring a new pump impeller.
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AF-600 FP Design Guide
2.7.23 Secondary Pumps
Secondary pumps in a primary/secondary chilled water pumping system are used to distribute the chilled water to the loads from the primary production loop.
The primary/secondary pumping system is used to hydronically de-couple one piping loop from another. In this case. The primary pump is used to maintain a
constant flow through the chillers while allowing the secondary pumps to vary in flow, increase control and save energy.
If the primary/secondary design concept is not used and a variable volume system is designed, when the flow rate drops far enough or too quickly, the chiller
cannot shed its load properly. The chiller’s low evaporator temperature safety then trips the chiller requiring a manual reset. This situation is common in large
installations especially when two or more chillers in parallel are installed.
2.7.24 The AF-600 FP Solution
While the primary-secondary system with two-way valves improves energy savings and eases system control problems, the true energy savings and control
potential is realized by adding frequency converters.
With the proper sensor location, the addition of frequency converters allows the pumps to vary their speed to follow the system curve instead of the pump curve.
This results in the elimination of wasted energy and eliminates most of the over-pressurization, two-way valves can be subjected too.
As the monitored loads are reached, the two-way valves close down. This increases the differential pressure measured across the load and two-way valve. As
this differential pressure starts to rise, the pump is slowed to maintain the control head also called setpoint value. This set-point value is calculated by summing
the pressure drop of the load and two way valve together under design conditions.
NB!
Please note that when running multiple pumps in parallel, they must run at the same speed to maximize energy savings, either with individual dedicated drives
or one frequency converter running multiple pumps in parallel.
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2.8 Control Structures
2.8.1 Control Principle
2
Illustration 2.5: Control structures.
AF-600 FP Design Guide
The frequency converter is a high performance unit for demanding applications. It can handle various kinds of motor control principles such as U/f special motor
mode and advanced vector control and can handle normal squirrel cage asynchronous motors.
Short circuit behavior on this drive depends on the 3 current transducers in the motor phases.
In par. H-40 Configuration Mode it can be selected if open or closed loop is to
be used
2.8.2 Control Structure Open Loop
Illustration 2.6: Open Loop structure.
In the configuration shown in the illustration above, par. H-40 Configuration Mode is set to Open loop [0]. The resulting reference from the reference handling
system or the local reference is received and fed through the ramp limitation and speed limitation before being sent to the motor control.
The output from the motor control is then limited by the maximum frequency limit.
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AF-600 FP Design Guide
2.8.3 Local (Hand) and Remote (Auto) Control
The frequency converter can be operated manually via keypad or remotely via analog/digital inputs or serial bus.
If allowed in par. K-40 [Hand] Button on Keypad, par. K-41 [Off] Button on Keypad, par. K-42 [Auto] Button on Keypad, and par. K-43 [Reset] Button on Keypad, it is
possible to start and stop the frequency converter bykeypad using the [Hand] and [Off] keys. Alarms can be reset via the [RESET] key. After pressing the [Hand]
key, the frequency converter goes into Hand Mode and follows (as default) the Local reference set by using the keypad arrow keys up [
After pressing the [Auto] key, the frequency converter goes into Auto mode
and follows (as default) the Remote reference. In this mode, it is possible to
control the frequency converter via the digital inputs and various serial in-
terfaces (RS-485, USB, or an optional network). See more about starting,
stopping, changing ramps and parameter set-ups etc. par. group O-5# (serial
communication).
] and down [▼].
▲
2
Hand Off
Auto
keypad Keys
Hand Linked to Hand / Auto Local
Hand -> Off Linked to Hand / Auto Local
Auto Linked to Hand / Auto Remote
Auto -> Off Linked to Hand / Auto Remote
All keys Local Local
All keys Remote Remote
The table shows under which conditions either the Local Reference or the Remote Reference is active. One of them is always active, but both can not be active
at the same time.
Local reference will force the configuration mode to open loop, independent on the setting of par. H-40 Configuration Mode.
NB!
Local Reference will be restored at power-down.
Reference Site
par. F-02 Operation Method
Active Reference
2.8.4 Control Structure Closed Loop
The closed loop controller allows the drive to become an integral part of the controlled system. The drive receives a feedback signal from a sensor in the system.
It then compares this feedback to a set-point reference value and determines the error, if any, between these two signals. It then adjusts the speed of the motor
to correct this error.
For example, consider a pump application where the speed of a pump is to be controlled so that the static pressure in a pipe is constant. The desired static pressure
value is supplied to the drive as the set-point reference. A static pressure sensor measures the actual static pressure in the pipe and supplies this to the drive as
a feedback signal. If the feedback signal is greater than the set-point reference, the drive will slow down to reduce the pressure. In a similar way, if the pipe
pressure is lower than the set-point reference, the drive will automatically speed up to increase the pressure provided by the pump.
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