GOODWIN P20 Operation Manual

OPERATION MANUAL

for the

GOODWIN P20

AIR PLASMA CUTTING SYSTEM

P20 Instruction Manual Revision : 12 27th March 1998

The Company reserves the right to make such changes to the design or specification of the
equipment as it shall see fit. The information contained in this manual is issued for the guidance
of users and does not form part of any contract. It is strongly recommended that all users and
supervisors familiarise themselves with the contents...

PRIOR TO COMMENCING USE OF THE SYSTEM

...and in particular, the section on safety precautions which should be used as a guide to safe
operation in accordance with the requirements of the relevant Health and Safety at Work
legislation.

AIR PLASMA LIMITED

3 LIMEHURST AVE
LOUGHBOROUGH

LEICESTERSHIRE

LE11 1PE

ENGLAND

Tel No. ++(0) 01509 237369

Fax No. ++(0) 01509 234942

Email. [e-mail]

Contents

1............................................................................................................................................... SAFETY 4

1.1 ............................................................................................................................................... General 4

1.2 ...................................................................................................................................Safety Features 5

1.3 .....................................................................................................................................W arning Signs 5

1.4 .....................................................................................................Packaging Handling and Transport 5

2 . ..................................................................... INTRODUCTION TO THE PLASMA PROCESS 6

3 . ............................................................................................................................. INSTALLATION 7

3.1 ......................................................................................................................................Power Supply 7

3.2 ............................................................................................................................Earth Requirements 7

3.3 .......................................................................................................................... Phase Determination 8

4 ................................................................................... PLASMA AND TORCH CONNECTIONS 9

4.1 ..................................................... Connecting the Torch and Plasma Earth Lead to the Power Unit 9

4.2 ......................................................................................................................Control of Hand Torch 10

4.3 .................................................................................................................Control of Machine Torch 10

5 ....................................................................................................................................OPERATION 11

5.1 ..............................................................................................................................Machine Controls 11

5.1.2 ....................................................................................................................... Warning Indicators 13

5.2 ........................................................................................................................Power Up Procedure 14

5.3 .............................................................................................................................Cutting Procedure 15

5.3.1. .........................................................................................................Starting and Finishing a Cut. 15

5.3.2, ................................................................................................................ Cutting With Stand Off. 15

5.3.3. ...............................................................................................................................Cutting Speed. 16

5.3.4. ............................................................................ Piercing Thicker Materials with a Hand Torch 17

5.3.5. .....................................................................................................Piercing with a Machine Torch 18

5.4 .................................................................................................................................Troubleshooting 19

5.5. .............................................................................................................................Consumable Life. 19

5.5.1. ................................................................................................................................ Intrinsic Life. 19

5.5.2. .....................................................................................................................................Alignment. 19

5.5.3. ....................................................................................................................... Transient Damage. 19

5.5.4. .................................................................................................................... Operational Damage. 20

5.5.5. .............................................................................................................. Electrode “non-starting”. 20

5.6 .....................................................................................................................Changing Consumables 21

6........................................................................................................................TECHNICAL DATA 23

6.1 ....................................................................................................................................... Power Unit 23

6.1.1. ..............................................................................................................................Electrical Input 23

6.1.2. ...........................................................................................................................Electrical Output 23

6.2 .......................................................................................................................... Torch and Hose Set 23

6.2.1 ....................................................................................................................................Hand Torch 23

6.2.2 ...............................................................................................................................Machine Torch 23

7 . .......................................................................................................... SERVICE INFORMATION 24

7.1 ................................................................................................................................ The Power Unit 24

7.1.1. ............................................................................................................................ Circuit Diagram 25

7.1.2. ................................................................................................................... Diagnostic Indicators. 26

7.2 .......................................................................................................The Torch and Hose Set Repair 27

7.3 ..................................................................................................................................... Maintenance 28

8 . ............................................................................................................................... Torch Blockage 29

8.1 ..................................................................................................................................Machine Torch 29

8.2 .........................................................................................................Machine Torch exploded View 30

8.3 .......................................................................................................................................Hand Torch 31

8.4 .............................................................................................................. Hand Torch exploded View 32

10. ......................................................................................................................................Fault Finding 33

10................................................................................................................................................ Index 34

1. SAFETY

1.1 General

Before any cutting operations are started, the user must ensure that the installation and proposed

working methods comply with all relevant safety regulations, environmental and electricity standards.

The plasma arc produced at the torch head is a jet of high energy and is potentially dangerous.
Users unfamiliar with a plasma arc should seek basic training. Goodwin Air Plasma can offer compre­hensive training courses.

In addition, the following points are particularly important:

a) The mains connection must be properly grounded and the supply lines fitted with fuses of
the specified rating. The mains cable must be properly secured and protected from possible
damage.
b) High voltage exists at the torch when power is applied and the pilot arc is struck (up to
300V), and when the main arc is cutting (150V). Under no circumstances should anyone
touch the nozzle with power applied to the torch. All adjustments and replacement of parts
should be done with the power unit supply isolated. The torch should not be used in
excessively wet conditions or if the torch or hose set are damaged in any way .
c) The mains supply should be isolated from the unit A T THE SUPPL Y before removing any
panels from the unit. Only authorised service personnel should remove panels.
d) Keep the work area clear of all inflammable materials. Ensure that any material ejected
from the cut is not a hazard to the operator or to others.
e) Protection is necessary against ultraviolet radiation emitted from the arc. A helmet or
shield with shade glass is recommended. W ear gloves and adequate protective clothing
where appropriate. Adequate screening should be arranged to protect others in the vicinity or
passing by in a similar manner to that required for arc welding operations.
f ) Adequate ventilation or fume extraction to remove the cutting fume and dust is required at
all times around any plasma cutting operation. When cutting flat sheet, a shallow water
bed cutting table will greatly reduce the fumes and dust which mainly occur below the cut.
g ) The wheels on the unit are meant for ease of movement around the work place and should
not be used over rough surfaces nor at excessive speeds.
h ) The plasma power unit should be positioned on stable level ground and if necessary
secured against any unwanted movement.
i ) The operation of this equipment and the plasma cutting process can result in noise levels
that could be harmful, The employer should undertake a noise assessment to monitor
compliance with relevant legislation.
j) Material to be cut should be supported in such a way that any material cut from the work
piece will not be a hazard and fall onto the user, the equipment, or others in the vicinity .
k) Care should be taken when manoevering the hose set with either a hand held torch or one
connected to a robot arm or profiler, that it does not snag on objects or other equipment
which may result in damage to the hose set, or topple the objects or equipment. Hose sets
that are subject to excessive mechanical tension may result in damage to the hose set
connections at the machine or the hose set components themselves.

1.2 Safety Features

The plasma unit includes the following features for the safety of the operator:

* The body of the plasma torch is earthed.
* The continuity of the torch earth and the voltage on the body is monitored.
* Cutting current flowing in the supply earth is monitored.
* The voltage on the torch nozzle is monitored.
* In the event of a faulty condition of the above, the machine will switch off power to the

torch.

The emergency stop procedure is to turn the main isolator to the off position, which is located on the
lower front control panel.

A tool (flat bladed screw driver) is required to remove the canopy for access to the internal compo­nents. Under no circumstances should the canopy be removed whilst the mains supply is still connected.
Only suitably trained and authorised personnel should remove the canopy.

1.4 Packaging Handling and Transport

Should the plasma unit need to be shipped, we recommend re-use of the original packing crate. Also:-

a) That the hose set be disconnected to prevent any damage to the hose set / plasma connections.
b) That the control panel is adequately protected against potential damage.
c) Any lifting should be done using the eyebolt located in the top of the canopy together with certified
lifting equipment (not supplied). Precautions should be taken to prevent rotation about the eyebolt.
d) The plasma unit should be shipped and stored in the upright position to avoid any heavy internal
components breaking free from their mountings.
e) Storage should be undercover, preferably in a clean dry environment.

1.3 W arning Signs

The location of the warning signs fitted to the plasma
unit are:

a) At the front of the machine ­W arning Open Circuit V oltage 300 volts.

b) At each rear lower corner of the canopy -

W arning Disconnect the Mains Supply.....

These should be maintained in a legible condition.

2. INTRODUCTION TO THE PLASMA PROCESS

The plasma process is created by passing a stream of clean ionised air, provided by an oil free
compressor, through a NOZZLE in the torch. The air stream is ionised by a PILOT ARC, initiated by a
HIGH FREQUENCY unit (HF Unit) which passes from the ELECTRODE to the nozzle when the
torch is activated. When the PILOT ARC is brought close to the work piece, MAIN ARC is
TRANSFERRED to the work piece as a jet of high energy which rapidly melts any metal with which it
makes contact, providing fast cutting, low residual heat input, and low material distortion.

The electrode and nozzle are cooled by air (and water in water cooled torches), and as the air is passed
through the nozzle it is caused to swirl around the arc by a SWIRL BUSH to aid stability of the arc.

The HF unit operates automatically to establish an arc when power is applied to the torch and it ceases
to operate when the pilot or main arc is established.

3. INSTALLATION

May be carried out by a competent electrician. No specialist tools are required.

3.1 Power Supply

The power unit is provided with a length of flexible cable which must be connected to a 3 phase and
earth electrical supply . The supply should be fitted with fuses or circuit breakers of appropriate rating
and a means of isolating the power unit from the supply should be provided. A plug should be fitted if
appropriate. The machine is phase/rotation sensitive.

Refer to the rating plate on the machine and T echnical Data section 6.1.1. for the correct voltage and
current requirements.

3.2 Earth Requirements

The installation should be arranged such that the only path to earth (or ground) from the work piece is
by way of the plasma earth lead connected to the front of the machine.

Where the material to be cut forms part of the structure which is earthed or grounded to the mains
electrical supply system, then the cutting current could flow through that route rather than the plasma
earth lead to the machine. Always ensure that there is a good connection between the work piece and
the machine via the plasma earth lead as a poor connection will cause excessive current in the mains
supply earth which will create a current trip fault condition (see section 7.4 fault finding).

In installations where it is not possible to avoid earth current trips, even though a good cutting current
earth path has been ensured, it will be necessary to check that the alternative mains earth paths are
substantial enough to carry higher currents than the current trip setting of 10 amps without causing
damage, as where the cutting earth is not connected to the work piece at all, this would be the full
cutting current. If the earth paths are not substantial they must be uprated or re-routed to avoid the
possibility of damage. Once the necessary checks and precautions have been taken, the earth current
trip circuit may be disabled by means of the switch on the Earth Current Relay (ECR) located inside the
power unit.

3.3 Phase Determination

Connect the torch to the machine (see section 4).

Fill the water system with distilled water.

Note. T o avoid damaging the water pump the machine should not be run without water in the
system, also, the machine should not be run for more than a few seconds without a torch connected to
the machine.

Switch on the machine by rotating the main isolator and pressing the on/off button ensuring the access
door is closed and the emergency stop switch is unlatched.

Correct phase connection is determined by checking that the cooling air flowing through the power unit
is from the left hand panel to the right of the machine. Also, the water light will be illuminated if the
motors are rotating incorrectly . If these conditions are not correct, change two of the three phase
connections at the power supply and check again.

If there is any doubt regarding installation, consult your distributor or Goodwin Air
Plasma.

4. PLASMA AND TORCH CONNECTIONS

4.1 Connecting the Torch and Plasma Earth Lead to the
Power Unit

Note. Do not run the power unit without the torch connected.

The connections to the power unit are located behind the access door at the front of the unit. The torch
hose set must pass through the aperture below the door before making the connections. Care must be
taken to obtain good connections.

T orch connection to the power unit is made by a composite hose set.

W ater supply line - Blue hose with short push in connector.
W ater return line - Blue hose with long push in connector.
Air and Power line - Black hose and orange cable with screw fitting.
Pilot Arc/T orch earth line- Black Co-axial cable with plug and screw collar.
Pilot earth/control line - White 3 Core cable with 3 pole plug.

The plasma earth lead is connected via the push in and twist clockwise socket.

Note. The access door is interlocked with the control circuit hence needs to be shut before the
power unit will operate.

The water fittings cannot be fitted incorrectly although the return line (long) will fit in the supply outlet
(short) for back flushing the torch. T o remove the water hoses, push the water connector collars to
release (both together to avoid loss of water).
When first switching on, allow enough time for the water to circulate through the system. T op up the
radiator as required. Use only distilled or de-ionised water. (See section 7.1 regarding use of methanol
in freezing conditions).

DIAGRAM TO SHOW HOSE SET CONNECTIONS

EARTH
CONNECTION

HOSE SET

ACCESS
DOOR

4.3 Control of Machine Torch

If the machine torch is used, plug the remote control (optional extra) plug into the remote control
socket.

If the machine is to be interfaced to a profiling machine, robot or other automatic system, the following
remote control socket connections may be used.

Pilot arc relay contacts can also be provided when necessary . If in doubt contact Goodwin Air Plasma
for advice on interfacing to other equipment.

REMOTE CONTROL
SOCKET

12volt supply

Earth

Arc Transfer
signal

Plasma On

plasma on
contacts
(12V dc
100mA)

pin 1

2

3

4

Plasma
On

4.2 Control of Hand Torch

The hand torch is provided with a press on / release off control switch on the handle for operation of the
plasma arc.

Note. Cooling air will flow through the torch at all times when the machine is switched on.

If a hand torch is to be used in conjunction with a mechanical manipulator or tractor unit etc., when the
operation of the handle mounted press on / release off control switch will not be possible, plug the
remote control (optional extra) switch unit into the remote control socket as for the machine torch.

Diagram to show Automatic Machine Interface.

+12 volts on main arc transfer
(switched to ground)

12 VOL T
RELA Y

5 OPERATION

5.1 Machine Controls

The front panel of the machine provides a range of displays and control gear to ensure correct operation

VOL TMETER

EMERGENCY STOP

W ARNING
INDICA TORS

ON / OFF BUTTONS

MAIN ISOLA TOR

OUTPUT ON LAMP

AMPMETER

AIR PRESSURE GAUGE

POWER CONTROL

SWITCH

AIR REGULA TOR

ACCESS DOOR

HOSE SET

ON / OFF BUTTONS
Switches auxiliary circuits on and off. ie Compressor, water pump, cooling fan and control circuits

MAIN ISOLA TOR
Isolates machine from mains supply . It may be padlocked in the off position.

EMERGENCY STOP
Switches machine off. The switch latches mechanically and must be rotated to release.

DOOR INTERLOCK
If the access door is open the machine will not work.

HOSE CONNECTIONS
See section 4. Connectiong the torch to the power unit.

VOL TMETER
Indicates the arc voltage.
T ypical values would be: Power applied to torch but no arc 300v

For Pilot Arc 250 to 280 volts
For Main Arc 120 to 180 volts

AMPMETER
Indicates the arc current.
T ypical values would be: Power switch set to 5kw 50 amp

10kw 90 amp
15kw 120 amp
20kw 150 amp

OUTPUT ON LAMP
Indicates that power is applied to the torch.

AIR PRESSURE GAUGE
Displays the back pressure in the system during the pilot arc and cutting modes
T ypical values would be: For Pilot Arc 0.7 to 1.4 bar (10 to 20 psi)

For Main Arc 2.4 to 3.4 bar (35 to 50 psi)
AIR REGULA TOR
Sets the air flow through the torch to give a stable pilot arc.

WATER

EARTH SAFETY

TEMPERA TURE

EARTH CURRENT

POWER

PILOT TRIP

POWER INDICA T OR ­Indicates that power is available to the system control circuit.

TEMPERA TURE INDICATOR ­Indicates that the rectifier or transformer temperature is too high.

WA TER INDICATOR ­Indicates insufficient water flow in the torch.

EARTH CURRENT INDICATOR ­Indicates excessive currents in the supply earth (see section 3.2).

EARTH SAFETY INDICATOR ­Indicates a break in the earth connection to the torch or a voltage in excess of 10 volts to the torch body .

PILOT TRIP INDICA TO R ­Indicates the pilot arc has excessive current, due to consumable condition or insufficient air flow .

5.1.2 Warning Indicators

See section 7.1.2 Displays and Controls for more details.

5.2 Power Up Procedure

Having completed the mains and cutting earth wiring, connected the torch and checked the fan rotation,
the machine is ready for use.

Switch the machine on and after allowing time for the water to circulate through the torch, press the
water reset button on the front panel. The red indicators should go out.

T o ascertain the absence of air leaks, the air regulator should be wound fully clockwise and the pressure
gauge should indicate a back pressure in excess of 1.6 bar.

It is now necessary to adjust the air pressure to give the highest possible reading consistent with good
arc starting and a stable pilot arc, this should around 0.9 bar . Switch on the torch with the nozzle well
clear of any work piece, person or equipment, and re-adjust the air pressure until it is at maximum or
the pilot arc becomes unstable (very noisy , misfire, and the voltmeter showing 300 volts). At this point
reduce the pressure to restore stability (arc less noisy , stable arc, and the volt meter showing 250/280
volts).

Always maintain as high an air pressure as possible for pilot arc as this gives the best consumable life.

The output lamp is “on” and the voltmeter reads between 250 vdc and 280 vdc at this stage.

NOTE.

As plasma power units do not have a voltage stablised power supply , a fluctuation in the input voltage
will directly affect the output current. This may not be noticeable if the input voltage rises slightly above
the norm as it will provide more power for cutting. If the rise is excessive, consumable life may suffer .
However, when the input voltage falls, the output power also falls, af fecting both the pilot arc and main
arc. In these circumstances it will be necessary to adjust the air pressure regulator to reduce the airflow
to obtain a stable pilot arc, and readjust it when the mains voltage returns to normal.

IMPORTANT

If the arc should “flare”, be coloured green, or emit any unusual noise, it is recommended that the unit be
immediately switched off and the condition of the consumables checked. Cutting under these conditions
may result in damage extending beyond the consumables to other parts of the torch.

Under normal cutting conditions the torch is designed to
operate with a ST AND OFF of about 6 mm (except P50
8 mm). This is the distance between the end of the nozzle
and the work piece.

Where the work piece is rusty , scaly, or with thick
sections of steel or aluminium etc., a build up of dross on
the top of the work piece may occur which will cause
damage to the nozzle. In these conditions, the stand off
distance should be increased slightly .

A guide ring is avalable to assist the operator in
maintaining the desired stand off height. This can also be
used against a straight edge to maintain a straight cut.

5.3.2.Cutting With Stand Off.

5.3 Cutting
Procedure

Where possible it is better to start a cut at a plate edge or hole because the piercing process reduces
consumable life.

Cuts can be started by either initiating the pilot arc and moving the torch into the proximity of the work
piece, or by positioning the torch over the edge of the work piece and starting the pilot arc.

Materials with a capacity to absorb heat energy , especially thicker sections, require more care and
technique when starting a cut. In these cases the cut will appear slow to start and pierce through the
material. Once a cut is established then cutting speeds may be increased.

Cutting can be stopped either by releasing the torch switch, switching off the power , or by withdrawing
from the workpiece (best done rapidly).

5.3.1.Starting and Finishing a Cut.

5.3.3.Cutting Speed.

Best results are usually obtained by cutting at the optimum cutting speed.

OPTIMUM CUTTING SPEED
Correct cutting speed is judged by experience from
observing the angle at which the cut material leaves the
lower edge of the plate, either by observing the ejected
material or by studying the surface of a cut after complet­ing a test cut. The drag back of the arc is aproximately 30
degrees.

CUTTING TOO SLOW
Arc appears to blow straight through the material.
Excessive dross may accumulate on the underside of the
material.

CUTTING TOO F AST
Arc fails to pierce the material. Blow back of dross will
damage the nozzle.

MAXIMUM CUTTING SPEED
Drag back of the arc is around 45°, but cut quality will
deteriorate.

5.3.4.Piercing Thicker Materials with a Hand Torch

Piercing will cause cut material to be ejected upwards which can be dangerous, and has a risk of damaging
the torch nozzle. This problem is worsened as material thickness increases because it takes longer to
pierce. If it is necessary to pierce, then it is best done by angling the torch and gradually bringing it upright
as piercing is completed.

Initiate the pilot arc and lay the torch over at approximately 60º

Begin twisting the torch slowly towards a vertical position taking
care to avoid ejected material from hitting the nozzle. At the
same time, the torch should be moved a small distance along the
work piece.

As piercing completes, the nozzle can be brought to vertical and
cutting can continue.

If the torch is pivoted about the nozzle there is a risk of material
being blown back onto the nozzle which will cause damage to the
nozzle or even to the torch itself.

*

Imaginary pivot point. X

X

X

X

X

5.3.5.Piercing with a Machine Torch

When using a machine torch, it is not generally possible to angle the torch for piercing.
Start the pilot arc above the work piece, and with the torch travelling at about half of the normal cutting
speed, lower the torch until main arc transfer occurs.
Once piercing is complete, the torch may be brought to normal stand off and cutting speed.

Goodwin Air Plasma offer an Automatic Height Control Unit as an optional extra for machine torches
integrated with profiling machines or robot arms. Ask your distributor or Goodwin Air Plasma for
further details.

ST AND
OFF

20MM

15MM

10MM

NORMAL

ê

è

Position the torch around 20mm from the work
piece, start the pilot arc and torch manipulator
moving at half speed.

Lower the torch until main arc transfers.

At this point, the descent speed of the torch is
important. If it is too fast, the ejected molten metal
will damage the torch.

Continue to lower the torch slowly after arc
transfer until the nozzle is 10mm from the work
piece.

W ait until the arc has completed piercing through,
then lower the torch and maintain a normal stand
off for the duration of the cut. Cutting can now
continue at the full recomended speed.

è

è

è

ê

ê

è

Bevel is more noticeable on thinner sections and is more pronounced on the left hand side of a cut. It is
due to the clockwise swirling of the air induced by the swirl bush in the electrode assembly . Bevel edges
can be desirable as an aid to weld preparation, however it can be virtually eliminated by reducing the
cutting speed but at the expense of accumulated dross. For minimum bevel cut clockwise around a
component and anticlockwise in a hole.

5.5.Consumable Life.

A good consumable life is the single most important factor in achieving optimum cutting economics of
any plasma cutting unit. This life is dependent on the intrinsic life of the consumables, correct alignment
and the incidence of transient and operational damage.

5.5.1.Intrinsic Life.

The intrinsic life of the consumables is determined by the rate at which they are eroded by the arc
process. This erosion rate is however low , and in practice, the life is limited by other factors. The insert
in the centre will be eroded slightly each time the arc is struck eventually creating a visible crater . The
crater can be more than 2mm deep before the electrode is considered to be expired.

5.5.2.Alignment.

The alignment and construction of the Goodwin Air Plasma T orch is such that problems of grinding and
adjusting electrodes do not occur. W ith reasonable care taken in fitting the consumables, alignment
problems should not arise.

5.5.3.Transient Damage.

On starting directly onto main arc, it is occasionally possible to erode some of the copper from the
electrode before the arc settles onto the insert material. This generates a crater in the electrode and the
insert burns back to become flush. Consumable life is thus reduced if there is a high number of starts
relative to the total cutting time.

Cutting speed too slow . Torch consumables worn or damaged. Insufficient
air flow .

Damaged torch consumables. Nozzle blocked by dross or too close to
work piece. Insufficient air flow .

Nozzle orifice damaged. Electrode eroded “off centre”. Consumables
wrongly fitted.

Speed too high. Stand off too high. Arc not straight - consumables damaged
or misaligned.

Excessive dross on lower
edge of cut.

Double arcing.

Main arc not square to
work piece.

Excessive bevel or rounded
cut surface.

5.4
T roubleshooting

5.5.4.Operational Damage.

This is the most likely cause of limited consumable life. Since the arc is quite capable of cutting copper,
anything which causes the arc to deviate from the centre of the nozzle will result in damage to the orifice.
In extreme cases the arc passes not through the orifice but from the electrode to the nozzle and from the
nozzle to the work piece - DOUBLE ARCING, causing the rapid erosion of copper from both
electrode and nozzle.

The most common cause of these problems is from ejected cut material entering the orifice particularly
when piercing or obstructing the nozzle with the work piece.

It is best to operate within the maximum speed capabilities of the machine and avoid unnecessary
piercing or stop-start cutting whenever possible.

5.5.5.Electrode “non-starting”.

Occasionally , it may happen that it is difficult to start the pilot arc. This happens when the oxidized
material from the electrode insert is deposited over the surface of the copper electrode and inside the
nozzle. Starting can be improved by cleaning or scratching the surface of the electrode with a wire brush
or sharp implement. Always switch off the power unit before removing the nozzle for this purpose. Once
a “non-starting” electrode has been used a few times, starting usually improves.

It is not good practice to fire the pilot arc continually in midair without striking the cutting arc as this
oxidizes the surface of the electrode and leads to “non-starting” problems.

Since cutting usually improves a non-starting electrode, it may be desirable to use a piece of scrap
material and start the main arc immediatly by positioning the torch close to the material before switching
on. Once started, continue to cut for as long as possible before trying to re-initiate the pilot arc.

ILLUSTRA TION TO SHOW ELECTRODE DAMAGE

NEW ELECTRODE

USED ELECTRODE

WORN OUT

EXPIRED

5.6 Changing Consumables

The Goodwin Underwater PTU torch carries a number of elements known as the CONSUMABLES
which are eroded during the cutting process. They consist of:

a) Nozzle.
b) Electrode Assembly comprising:

Electrode
Swirl Bush
O ring

Other parts that may be damaged and replaced by the user are:

Front Cap
Front Cap Retaining and Sealing Rings

Front Insulator

Contact Tube.

TORCH HEAD

FRONT CAP RET AINING RING

FRONT INSULA TOR

FRONT CAP SEAL

CONT ACT TUBE

ELECTRODE ASSEMBL Y

NOZZLE

FRONT CAP

T o renew the consumables, the following procedure should be adopted, remembering that care and
cleanliness are of the utmost importance.

1. Recover the torch to the surface.

2. Switch the machine off at the mains supply or Main Isolator.

2. Remove the Front Cap. The cap is a push fit over the O ring seated in a groove in the outer diameter

of the T orch Body and engages with a sealing
ring on the Front Insulator.

3. Unscrew the Nozzle with the special tool
supplied. (See illustration left).

4. Check the condition of the Electrode
Assembly . If it is to be removed, grip the
Electrode Assembly with the special Electrode
Pliers provided, and pull firmly out from the
torch body . (See illustration right).

5. Press a new Electrode Assembly carefully but firmly over the contact tube until it is fully home and

central. Use the handle of the Nozzle T ool which has been prepared for this purpose. THIS IS
VERY IMPOR T ANT ! If the Electrode is not pressed fully home onto the Contact T ube, the Swirl
Bush may be partly crushed by the Nozzle, and will interfere with the airflow .

6. Carefully screw the Nozzle into the Torch Head using the special tool until fully home. DO NOT

OVER TIGHTEN.

7. Apply a liberal quantity of Silicone Grease around the front of the torch, especially to fill the space

between the nozzle, front cap and sealing ring.

8. Refit the push fit Front Cap. Apply additional grease over the outside of the front cap. The grease will

provide a first line of defence against material blown back from the cutting process.

Remember that cleanliness and care must be taken when fitting consumables. Do not allow dirt to
obstruct the threaded parts of the torch. T ake care when engaging threaded parts not to damage the
thread.

CONT ACT TUBE REPLACEMENT .

Should the Contact Tube need changing, it is removed by inserting the 1/8" allen key supplied into the
centre and unscrewing. Replacement is the reverse of removal but it is important not to over tighten
as this may cause subsequent electrode fitment to be off centre, producing bevel cuts.

6 . TECHNICAL DATA

6.1 Power Unit

6.1.1. Electrical Input

Input is via 3 core and earth flexible: 4 x 10mm2 3 metre length standard.
Machines are available for the following 3 phase supplies:

Input V oltage Input Current
380v 50Hz 65amp
415v 50Hz 60amp
440/480v 60Hz 57amp
575v 60Hz 43amp
Other voltages and frequencies available to order

6.1.2.Electrical Output

Open circuit voltage 300v dc
T ypical arc voltage 150v dc
Main arc power 20, 15, 10, 5kw switched

continuously rated
Pilot arc current 15 - 20 amps nominal
Duty cycle 100%

6.1.3 Miscellaneous

Compressor type Oi l free twin cy linde r.
W ater pump type Regenerative type.
W ater capacity 3 litre (aprox. dependant on hose length)

distilled or deionised water

6.1.4 Dimentions

Length 1000mm (39")
Width 700mm (22")
Height 800mm (31")
W e i gh t 360 kg (800 lb)

6.2 Torch and Hose Set

6.2.1 Hand Torch

T orch body diameter 40mm
T orch head weight 1.0 kg
Effective weight (inc. hose set) 1.5 kg
Hose set lengths available 7.5m, 15m, 20m, 30m, longer with Junction Box.
Hose set water capacity 0.6 litres per 10m length

6.2.2 Machine Torch

T orch body diameter 40mm
T orch body length 200mm
T orch head weight: 1.0 kg
Hose set lengths available 7.5m, 15m, 20m, 30m, longer with Junction Box.
Hose set water capacity 0.6 litres per 10m length

7.1.1. Main Circuits and Systems.

7. SERVICE INFORMATION

7.1 The Power Unit

Output power is supplied from a oil cooled transformer and rectifier with varistor diode protection. The
transformer is rated at 100% duty cycle.

The power is carried to the torch electrode by a cable within the hose set.
Pilot arc connection to the nozzle is made via a current limiting resistor in the rear of the machine and a
coaxial cable in the hose set. The HF arc ignition is fully automatic in operation, being powered from the
torch power lines.

The compressor, cooling fan, and water pump are the only “phase sensitive” components and it is essential
to ensure that their direction of rotation is correct according to the installation instructions (see section 3).
These components are protected by thermal / magnetic overload. If the overload should operate, after
establishing the reason for the trip (e.g. missing supply phase). It can be reset by first removing the machine
cover then pressing the manual reset button on the overload unit situated behind the instrument panel.

The water radiator and the pilot arc resistor, are cooled by an electric fan. A temperature sensing interlock
on the duct protects the system against thermal overload should the cooling fail or be obstructed hence it
is essential to ensure adequate air circulation around the machine at all times.

The air compressor is of the oil free, maintenance free, twin piston type fitted with two cleanable/
replaceable inlet filters contained in black screw-in housings with a snap open lids.

The high pressure water pump supplies cooling water to the torch through quick release, self sealing
couplings so that the torch can be disconnected without the loss of water from the system. There is an
interlocked flow sensor on the return line which shuts down the arc if the water flow should be restricted.

The header tank must be kept full of distilled water at all times. If site conditions dictate that antifreeze
should be used, then up to 33% METHANOL may be added.

NOTE. Ethylene glycol or automotive type antifreeze fluids MUST NOT BE USED, as they will cause
rapid corrosion of the torch.

Whenever any of the interlocks come into operation the appropriate warning light on the front panel will
indicate to assist in the diagnosis of the problem.

The Circuit Diagram is shown in drawing 1/D/10359

7.1.1. Circuit Diagram

OUTPUT ON LAMP
Indicates that power is applied to the torch.

POWER INDICA TOR
Indicates that 220V power is available to the system.

WA TER INDICATOR
Indicates no water in the system, a water leak, torch blockage, low pump supply pressure or incorrect
motor/fan rotation. See section 7.2 for torch blockage. When water flow is restored, the system will
reset automatically .

EAR TH SAFETY INDICA TOR
Indicates a break in the earth connection to the torch or a voltage in excess of 10 volts to the torch
body . This indicator will also illuminate as a self test when the machine is switched, on Depressing the
button will reset the system provided the fault is rectified.

TEMPERA TURE INDICA TO R
Indicates that the water or resistor temperature is too high. Cutting operations will immediately stop.
Leave the machine running to allow the fan to cool the water or resistors. The system will automatically
reset when the temperature drops.

EAR TH CURRENT INDICA TOR
Indicates the main arc cutting current is flowing in a secondary path. System will stop until the torch
switch is released. (See section 3.2 for cutting earth requirements).

PILOT TRIP INDICA TO R
Indicates the pilot arc has excessive current. The circuit will reset automatically when the torch switch is
released. Check air flow adjustment, air leaks,restricted air flow , or consumable condition.

7.1.2. Diagnostic
Indicators.

7.2 The Torch and Hose Set Repair

The torch is a precise assembly of electrically conductive parts and P .T .F .E. insulators housed in a
stainless steel body . It is supplied with compressed air, water and electrical power at high voltage which
must not be allowed to escape from their designed confines.

Rebuilding torches requires special training and instruction and is not within the scope of this manual.
Users who wish to repair damaged torches themselves should consult their supplier or Goodwin Air
Plasma for detailed advice.

A torches should be removed from the power unit complete with hose set. Once removed, the torch
head may be serviced or repaired.

If a spare torch and hose set is available, the machine may be put back in service whilst repairs are
carried out.

TORCH BLOCKAGE.

The water flow in the torch can occasionally become blocked, usually with scale because deionised /
distilled water has not been used or has become contaminated. Also, copper deposits can accure as a
result of expiry of an electrode. See section 8 of this manual.

TORCH / HOSE JUNCTION BOX ON MACHINE INST ALLATIONS .

A Junction box is offered as an optional extra to provide a facility for the fast removal of the torch head.
Useful for service or change of use with minimum loss of production time, the junction box links all the
control services carried by the hose set to the torch. Another advantage of the junction box is that it will
allow the majority of the hose set, which may be lengthy and difficult to remove from an automatic
machine, to remain in situ.

7.3 Maintenance

Daily

Monthly

(depending on usage)

Annually

more frequently in poor conditions or

with high usage

Check condition of the consumables.

Top up water reservoir with distilled /

demineralised water.

Check for water and air leaks, clean the air

compressor intake filters.

Remove excessive dust from inside the machine

taking care not to damage any mechanical or

electrical component and avoid exposure to this

dust which may represent a health hazard. Use

personal protection as necessary .

Replace the compressor air intake filter. Check

tightness of all electrical and mechanical

connections. Check the correct operation of all

controls and indicators.

Goodwin Air Plasma Cutting Systems are designed so that only a minimum amount of maintenance is
required. By following a regular and careful maintenance procedure, the equipment will give a long productive
life.

8. Torch Blockage

The torch can become blocked if deionised / distilled water is not used, or with copper deposits when the
electrode expires. In both cases the blockage accrues in the Cathode Block, Centre Insulator and Nozzle
Holder. The torch head will need to be partially dismantled to rectify this condition. This operation must
only be carried out by a competant electrical fitter.

8.1 Machine T orch

1. Remove the Nozzle and Electrode.

2. Remove three small grub screws from mounting tube.

3. Take care not to strain pipe connections to the torch.

4. Pull back the mounting tube and bagging to reveal all the connections of the hose set.

5. Remove safety insulator by carefully cutting with a sharp knife, taking care not to cut the in­sulation of the wires inside.

6. Unscrew torch body off the stub tube, put stub tube clear of torch head, and remove Front
Insulator.

7. Slide Back Cover up the Air/Power and W ater Pipes to reveal HF Strap and HF Screws.

8. Using a small flat bladed screw driver unscrew the two screws. This will allow the Nozzle
Holder to be removed.

9. Carefully ease out the Centre Insulator taking care not to lose the four W ater Seals. This
will reveal the Cathode Block.

10. Clean out the two water galleries using a small drill bit by hand, taking care not to push the
blockage any further into the Cathode Block.

11. Clean holes in the Centre Insulator in the same way.

12. The Nozzle Holder is cleaned in the same way, however this may have a blockage within the
circular water gallery, (check this by blowing into one of the holes, if the air flows freely it is o k
to re-use) if it is blocked it will need replacing before rebuilding the torch.

13. Check W ater Seals for damage. Replace if necessary and refit into Centre Insulator.

14. Check length of HF screws as they may have stretched. If they are over 35mm they should
be replaced.

15. Refit Centre Insulator to Cathode Block taking care not to dislodge W ater Seals.

16. Refit Nozzle Holder to Centre Insulator taking care to align screws with threaded holes and
tighten.

17. Pull back the Back Cover and Stub Tube taking care to align the two anti-rotationpins with
holes in Back Cover and ensure the Black, Green/Y ellow (Earth) and Red (HF) wires are
together.

18. Refit Front Insulator over Nozzle Holder, if this is damaged replace it.

19. Refit T orch Body over torch and screw onto Stub Tube taking care not to cross thread.

20. Fit new Safety Insulator by heat shrinking into place or taping the old one into place taking
care to cover all the exposed metal torch parts.
21 Pull back the Mounting Tube and refit the three grub screws.

22. Refit the Nozzle and Electrode to the torch.

23. Remove water return pipe connection from the Machine (Long water fitting) and start
Machine, allow water to run out until the air lock is released (the water jet will stop then restart).
Run machine for a further five seconds, this will allow any debris left in the torch head to be
ejected. Switch off Machine and reconnect hose set.

NOTE:- If the jet of water coming out of the removed return water connection is not

between 300 to 500mm long then the torch may still be blocked and should be stripped
down completely or sent to Goodwin Air Plasma for repair.

8.2 Machine T orch exploded V iew

8.3 Hand Tor ch

1. Remove the Front Cap, Nozzle and Electrode.

2. Remove Back Cap and Front Ring (using Special tool).

3. Remove Rear Cover by carefully tapping the side of the Torch on a piece of wood, this will
cause it to fall out. This will reveal the HF Strap and HF Screws.

4. Using a small flat bladed screw driver unscrew the two screws. This will allow the Nozzle
Holder to be removed.

5. Carefully ease out the Centre Insulator taking care not to lose the four W ater Seals. This
will reveal the Cathode Block.

6. Clean out the two water galleries using a small drill bit by hand, taking care not to push the
blockage any further into the Cathode Block.

7. Clean holes in the Centre Insulator in the same way.

8. The Nozzle Holder is cleaned in the same way, however this may have a blockage within the
circular water gallery, (check this by blowing into one of the holes, if the air flows freely it is o k
to re-use) if it is blocked it will need replacing before rebuilding the torch.

9. Check W ater Seals for damage. Replace if necessary and refit into Centre Insulator.

10. Check length of HF screws as they may have stretched. If they are over 35mm they should
be replaced.

11. Refit Centre Insulator to Cathode Block taking care not to dislodge W ater Seals.

12. Refit Nozzle Holder to Centre Insulator taking care to align screws with threaded holes and
tighten.

13. Refit Front Insulator over Nozzle Holder, if this is damaged replace it.

14. Refit Front Ring and Back Cap taking care not to cross thread.

15. Fit Nozzle and Electrode to torch.

16. Remove water return pipe connection from the Machine (Long water fitting) and start
Machine, allow water to run out until the air lock is released (the water jet will stop then restart).
Run machine for a further five seconds, this will allow any debris left in the torch head to be
ejected. Switch off Machine and reconnect hose set.

NOTE If the jet of water coming out of the removed return water connection is not between 300
to 500mm long then the torch may still be blocked and should be stripped down completely or sent to
Goodwin Air Plasma for repair.

8.4 Hand T orch exploded View

f) Broken HF cable on hose set T elephone Goodwin Air Plasma

Current trip indicator a) Electrode incorrectly fitted Refit correctly
coming on

b) Low air flow through torch Increase flow , check for air leaks

c) A path to mains earth Ensure workpiece is completely

isolated from mains earth

Misfiring pilot arc a) Too much air flowing through Decrease flow

torch
b) Blown diode T elephone Goodwin Air Plasma

Tracking :- a) Slag build up on Front Cap Clean slag from around Nozzle
Spark appears at front of
torch and no pilot arc. b) Front Insulator damaged Replace Front Insulator

Front Caps and Nozzles a) Incorrect operation of torch See operating instruction pages
burning up rapidly

b) Not using Silicone Grease Apply Silicone Grease

Excessive bevel, poor cut a) Damaged Consumables Change Consumables
quality

b) Electrode eroded off centre Change Consumables

c) Misaligned Consumables Change Contact T ube and

consumables

d) Low air pressure Clean air filters, check for air

leaks.

e) Cut speed too fast See operating instruction pages

f) Stand off too high See operating instruction pages

9. Fault Finding

Below is a list of the most common reasons for non operation of a Goodwin Air
Plasma Cutting System.

Symptom Probable cause Remedy

No Pilot arc at torch head a) Machine Ready Light not onCheck for red indicator being on
when torch button is (If so refer to Manual)
depressed b) Output Indicator not on Check torch switch and 220v fuse

As above with output c) Non starting electrode (R efer to manual)
indicator on

d) V olt meter not reading 300v Telephone Goodwin Air Plasma

As above with voltmeter e) No HF in the HF Box T elephone Goodwin Air Plasma
reading 300v

10. Index

A

Accessory

Junction box 27

C

Consumable

Life of 19, 20

Cutting

Bevel 19
Blow back 20
High Frequency (HF) 6
Main arc 6
Pilot arc 6
Process explained 6
Robot 4
V entilation 4
W ater table 4

E

emergency 5

F

Fault Finding

Bevel 19
Dross 19
Troubleshooting 19

G

Goodwin Air Plasma 2
Guide Ring 15

H

Health and Safety 2

P

Plasma

Process 4

S

Safety

General 4
Mains connection 4
Noise 4
Personal protection 4

Service

Hose 27
Torch 27
T orch blockage 27

T

Training 4