Rtech PLASMA P31C User manual

www.r-techwelding.co.uk
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PLASMA P31C
INVERTER PLASMA CUTTER
OPERATION INSTRUCTIONS
Version 2021-11

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Thank you for selecting the R-Tech Plasma 31C Inverter Plasma Cutter
The Plasma 31C has many benefits over traditional transformer plasma cutters, including infinite
power control, HF contact start and quick fitting cost effective torch, long-life cost-effective torch
consumables and a 35% industrial duty cycle
We want you to take pride in operating our Plasma 31C as much pride as we have taken in making
this product for you. Please read all information in this manual before operation
Pay particular attention to the safety instructions we have provided you for your protection
The level of seriousness to be applied to each section is explained below
WARNING
This statement appears where the information must be followed exactly to avoid serious personal injury.
CAUTION
This statement appears where the information must be following to avoid a minor personal injury or
damage to this equipment.
PLEASE EXAMINE CARTON AND EQUIPMENT FOR DAMAGE IMMEDIATELY
When this equipment is shipped, title passes to the purchaser upon receipt from the courier.
Consequently, all claims for material damaged in shipment must be made by purchaser against
the transportation company used.
Please record your equipment identification below for future reference. This information can be found on
data plate at rear of machine.
Product Plasma P31C
Serial No.
Date of Purchase
Where Purchased
Whenever you request replacement parts or information on this equipment, please always
supply information you have recorded above
This product is covered by 3 years parts and labour warranty, we will cover cost of collecting and
returning item to you (UK mainland only, other areas are RTB). External items, torch, earth lead etc. are
covered by 3 months warranty. Any faults/damage found caused by customer will be charged pro-rata

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Introduction
The R-Tech Plasma 31C is a member of our field acclaimed family of welding products.
Premium features include: -
1. Inverter power source – more efficient to operate, provides smoother weld characteristics.
2. Infinite cutting power adjustment, allows fine tuning of cut characteristics
3. HF start – Enables easy arc starting
4. Digital amp meter
5. Quick fitting torch for easy torch fitment/replacement
6. Long life – Low-cost torch consumables
7. 35% Duty cycle at 30 Amps @ 40ºC
Recommended Processes
The R-Tech Plasma 31C is recommended for the plasma cutting processes within its output capacity of
30 Amps DC
Equipment Limitations
The R-Tech Plasma 31C is protected from overloads beyond the output ratings and duty cycle as per
machine specifications with thermostat protection of the output coils and rectifiers.
Cutting Capability – Duty Cycle
The R-Tech Plasma 31C is rated at 30 Amps at 35% duty cycle on a ten-minute basis. If the duty cycle is
exceeded a thermal protector will shut machine off until the machine cools.
Technical Specifications
MODEL
PLASMA
31C
Power Voltage
240V 50/60Hz
AC
Input Current
10.5amps I
-eff (13amp fuse slow blow)
Rated Output Current
30A
Current Adjusting Range
15
- 30A
No
-load Voltage
200V
Rated Duty Cycle
35%
Working Mode
HF Contact Start
Air Pressure
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0 PSI – Working Air Pressure (Air flowing)
Max. Cutting Thickness (Clean cut mild steel)
8mm
Max.
Cutting Thickness (Severance cut mild steel)
12mm
After Flow Time
10 Seconds
Dimensions
390 X 190 X 290

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Safety Precautions
Read entire section before starting installation
WARNING!
Electric Shock can kill – Only qualified personnel should perform this installation. Turn off input power at
the fuse box before working on this equipment. Do not touch electrically live parts. Always connect the
machine to an earthed mains supply as per national recommended standards.
Select suitable location
Place the plasma cutter where clean cooling air can freely circulate in and out of the front & rear louver
vents. Dirt, dust or any foreign material that can be drawn through vents into plasma cutter must be kept
to a minimum. Failure to observe these precautions can result in excessive operating temperatures which
can lead to plant failure.
Grinding
Do not direct grinding particles towards the plasma cutter. An abundance of conductive material can
cause plant failure.
Stacking
This machine cannot be stacked.
Transport – Unloading
Never underestimate the weight of equipment, never move, or leave suspended in the air above people.
Always use recommended lifting equipment.
WARNING!
Falling Equipment can cause injury. Never lift plasma cutter with gas bottle attached. Never lift above
personnel.
Tilting
Machine must be placed on a secure level surface or on a recommended undercarriage/trolley. This
machine may topple over if this procedure is not followed.
Environmental Rating
The plasma power source carries the IP21S rating. It may be used in normal industrial and commercial
environments. Avoid using in areas where water / rain is around.

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Electrical Installation
WARNING!
ELECTRIC SHOCK CAN
KILL
Machine grounding and High Frequency Interference Protection
This plasma cutter must be grounded to earth. See national electrical codes for proper grounding
methods.
The high frequency generator being similar to a radio transmitter may cause interference to radio, TV
and other electronic equipment. These problems may be the result of radiated interference. Proper
grounding methods can reduce or eliminate this.
Radiated interference can develop in the following ways
1. Direct interference from welder power source
2. Direct interference from the welding leads
3. Direct interference radiated from feedback into power lines
4. Interference from re-radiation by un-grounded metallic objects.
Keeping these contributing factors in mind, installing equipment as per following instructions
should minimize problems.
1. Keep the welder input power lines as short as possible and enclose as much of them as
possible in metal conduit or equivalent shielding. There should be a good electrical contact
between this conduit and ground (Earth).
2. Keep the work and electrode leads as short as possible. Tape the leads together where
practical.
3. Be sure the torch and earth lead rubber coverings are free from cuts and cracks that
allow welding power leakage
4. Keep earth lead connection to work in good condition – Clean area on workbench where
earth clamp is situated on a regular basis.
Input Connections
Make sure the voltage, phase and frequency of input power is as specified on machine rating
plate located at rear of machine.
Have a qualified electrician provide suitable input power as per national electrical codes. Make
sure machine is earthed / grounded.
Make sure fuse or circuit breaker is correct rating.Using fuses or circuit breakers smaller than
recommended will result in ‘nuisance’ shut off from welder inrush currents even if cutting at low
amperages.
Failure to follow these instructions can cause immediate failure within the welder and void machines
warranty.
Turn the input power OFF at the mains switch & fuse box before working on this

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equipment. Have a qualified electrician install & service this equipment.
Allow machine to sit for 5 minutes minimum to allow the power capacitors to discharge before working
inside this equipment. Do not touch electrically live parts
The Plasma 31C Plasma Cutters requires a 240V 50/60Hz 1-Phase supply. It requires an 13A
supply. It comes with a mains cable attached.
Connect wires according to national coding.
Brown wire – Live, Blue wire – Neutral
Green/Yellow Wire – Earth (Ground)
Connecting to an Engine Driven Generator
If connecting this Plasma Cutter to an engine driven generator, please ensure
the following
Minimum Generator KVA Output – 5KVA continuous
Generator to be fitted with AVR (automatic voltage
regulation) DO NOT USE ON A GENERATOR WITHOUT
AVR
Connecting to a generator without the above minimum requirements will in-
validate your warranty.

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Connections for Plasma 31C
Air pressure connection / setting
1. Air pressure regulating knob
This regulates the air pressure as displayed in gauge on front of machine.
To adjust pressure, pull knob upwards and turn to adjust pressure, once correct pressure is
obtained press down knob to secure -Set air pressure to70psi when air is flowing through
torch.
2. Air inlet connector
Connect hose from air compressor onto standard male PCL fitting – Fitting can be changed
if required to suit.
Note: If regulator fills with water, unscrew thumbscrew underneath to slowly drain of water,
screw back tight once drained.

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Rear machine connections
1. On / Off Switch
Turns machine on and off, the switch illuminates when machine turned on
2. Mains input cable
Fit required plug as per your electrical installation
3. 2nd Earth Connector
This can be used to earth the machine to workbench if you are experiencing interference from the
HF – Sometimes required when using CNC automated machinery - Not normally used

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Front machine connections
1. Torch power connector
Connect the main torch cable and screw clockwise until tight
2. Torch switch socket
Connect the torch switch plug (2 pin) and screw on retaining ring to secure
3. Earth / Workpiece connector
Connect the earth lead to this connector.
Insert male connector into socket and twist clockwise until tight.
Secure other end of earth lead to Workpiece via the earth clamp

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Controls and Settings
1. Amperage control knob
This adjusts the amperage (cutting power)
2. Power on light
This lights when machine is switched on
3. Low air pressure warning
This lights when air pressure is too low, check air pressure is set to 70 PSI when air is flowing from
torch
4. Overheat warning light
This lights when machine has overheated – allow to cool and light to go out before using again –
if problem persists see troubleshooting later in this manual
5. Power warning light
This lights when machine has sensed and internal problem with machine.
Turn off machine and contact R-Tech technical support
6. Air pressure gauge
Displays air pressure in PSI
7. LED Display
This shows cutting amperage selected when control knob (1) is turned.

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Operating machine
SAFETY PRECAUTIONS
WARNING!
ELECTRIC SHOCK CAN KILL
Do not touch electrically live parts or electrode with skin or wet clothing.
Insulate yourself from work and ground
Always wear dry insulating gloves
WARNING!
FUMES AND GASES can be dangerous
Keep your head out of fumes & gases produced from welding.
Use ventilation or exhaust to remove fumes & gases from breathing zone and general area.
WARNING!
WELDING SPARKS can cause fire or explosion
Keep flammable material away from work area.
Do not weld on containers that have held combustibles
WARNING!
ARC RAYS can burn
Wear eye, ear and body protection – Make sure work area is protected by proper shielding to
avoid injury to passers-by.

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Operating Machine
Please ensure all torch consumables are tight before use
1. Ensure machine has been setup as previously stated
2. Turn on the machine, the power light will light up and cooling fan starts running
3. Press torch switch, air will flow from torch head, now set the air pressure in gauge using
adjuster on regulator on machine to 70PSI
Once the correct air pressure has been set press down the adjuster on air regulator.
4. Ensure earth clamp is connected to workpiece or workbench ensuring a good clean pointof
contact
5. Select cutting amperage knob to desired cutting power (the following guidelines will varyin
accordance with material grade, characteristics and user operation)
20 Amps for up to 6mm clean cut on mild steel
30 Amps for up to 8mm clean cut on mild steel
When cutting aluminium, alloys and stainless-steel cutting thickness is reduced by approximately
20%
6. Hold torch in starting position on work and press torch switch and the high frequency will initiate
contact with the workpiece and machine will automatically switch to main cutting power.
Once you come to the end of cut/workpiece the machine will sense this and turn off main cutting
power, to start cutting again, release switch and press again.
7. Getting correct amperage / cutting speed for desired job.
The combination of correct cutting amperage and travel speed can change per user, here are
some tips on obtaining optimum settings.
Blow back when cutting – If you experience blow back and the metal is not cut all the way
through, you either are traveling too fast or you need to increase the cutting amperage
Cutting arc is erratic and work is being cut all way through. You are traveling too slow/fast or
cutting with too high/low amperage for work.
It can take a while to get used to plasma cutting if never done before. Experiment with settings on
some scrap material until you find the best amperage / cutting speed for user.
If you ever have any questions on settings call us and speak to one of our experienced
technicians who will be happy to help you.

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Replacing torch consumables
WARNING!
ELECTRIC SHOCK CAN KILL
Please ensure machine is turned off before changing consumables
If cutting performance is poor, please check / change the torch consumables.
To change the plasma cutting consumables carry out the following procedure
1. Switch off machine
2. Ensure torch has cooled down to avoid burns
3. Unscrew the white ceramic shield cup
4. Remove the cutting tip
5. Check the condition of cutting electrode, replace cutting electrode if tip is worn 1-2 mm and end is
concave
6. Check condition of gas distributor insulator ring, replace if warn/cracked.
7. Fit new cutting tip if required –if cutting hole is distorted or an angled cut happens replace the cutting
tip.
8. Refit white ceramic shield cup by screwing on hand tight
9. Turn machine back on and continue cutting

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Maintenance
Routine and periodic maintenance
WARNING!
ELECTRIC SHOCK CAN KILL
Turn the input power OFF at the mains switch & fuse box and remove mains plug from socket before
working on this equipment.
Have a qualified electrician install & service this Plasma cutting equipment.
Allow machine to sit for 5 minutes minimum after disconnection from mains power to allow the power
capacitors to discharge before working inside this equipment.
Do not touch electrically live parts
1. Periodically (3-6 months depending on use / environment), remove the side/top panels of
machine and clean out machine with a low-pressure dry air line paying particular attention to PC
Boards, Fan blades and switchgear
Failure to maintain plant can void manufacturer's warranty.
2. Inspect input and output cables & hoses for fraying and cuts, replace if damaged present
3. Keep cutting torch and earth cables in good condition
4. Clean air vents to ensure proper air flow and cooling
5. The fan motor has sealed bearings which requires no maintenance

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FAULT DIAGNOSTICS
1. Power light not lit
Check machine on/off switch is in the ‘on’ position
Check Input power to machine
Check plug wiring
Check mains trip / fuses
2. No output - Fan runs - Power light is lit
Check torch connections are secure and torch switch operation, try replacing plasma cutting
torch
3. No output - Power light is lit - Warning light is lit
Welding application may have exceeded recommended duty cycle, allow machine to cool down
until the warning light goes out.
4. No output – Power light is lit – Air at torch tip – No cutting
Check condition of torch consumables and replace if worn
Check for water in water trap at rear of machine, if water is present, drain air compressor, clean
water out of air lines, empty water trap by pressing water release button on bottom of air
regulator water trap. Fit new consumables as per instructions earlier in this manual
HF PCB Failure – Contact R-Tech for repair
5. Machine keeps overheating - Warning light is lit on machine
Check if fan is running – if not contact R-Tech for repair
Check the cooling vents for obstruction, blow out machine with clean dry low pressure air
supply. Check for adequate ventilation around machine
6. Erratic cut – Torch spitting when cutting
Check torch consumables and replace, if necessary, as per instructions earlier in this manual
Check if correct amperage for thickness of metal, if travel speed is too fast or to not enough
cutting power for job.

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Water contamination in torch head, check for water in water trap at rear of machine, if water is
present, drain air compressor, clean water out of air lines, empty water trap by pressing water
release button on bottom of air regulator water trap. Fit new consumables as per instructions
earlier in this manual
Plasma Torch Consumables parts list
R-Tech Torch Spares
Plasma 31C Part No.
Electrode
P30-EL
Cutting Tip
P30-CT
Ceramic Shield Cup
P30-SC
Gas distributor insulator ring
P30-GD
Torch Head - Handheld
P30-THH
Torch Complete - Handheld 6M
P30-4.5MHHT

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