Rtech PLASMA 50HF User manual

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PLASMA 50HF
INVERTER PLASMA CUTTER
OPERATION INSTRUCTIONS
Version 2020-05 LT70

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Thank you for selecting the R-Tech PLASMA 50HF Inverter Plasma Cutter
The PLASMA 50HF 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 60%
industrial duty cycle
We want you to take pride in operating our PLASMA 50HF as much pride as we have taken in making this product
for you. Please read all information in this manual before operation
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 50HF
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 3years collect and return UK warranty, R-Tech will cover cost of collection, repair and return of
item to UK mainland (other areas are RTB). External items, torch, earth lead etc are covered by 3 months warranty. Any
faults/damage found caused bycustomer will be charged pro-rata.
Pay particular attention to the safety instructions we haveprovided you for your protection. The level of
seriousness to beapplied to each sectionis 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.

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Introduction
The R-Tech PLASMA 50HF 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 Pilot start - Enables easy arc start even on painted surfaces
4. HF pilot arc restart - ideal for cutting mesh etc
5. Digital amp meter
6. Quick fitting torch for easy torch fitment/replacement
7. Long life -Low cost torch consumables
8. 60% Duty cycle at 50 Amps @ 40OC
Recommended Processes
The R-Tech PLASMA 50HF is recommended for the plasma cutting processes within its output capacity of 50
Amps DC
Equipment Limitations
The R-Tech PLASMA 50HF is protected from overloads beyond the output ratings and duty cycle as per machine
specifications with thermostat protection of the output coils and rectifiers and is rated at 50 Amps at 60% 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
Power Voltage
Fuse rating
Rated Output Current
Current Adjusting Range
No-load Voltage
Rated Duty Cycle
Starting Mode
Air Pressure
Max. Cutting Thickness (Clean cut mild steel)
Max. Cutting Thickness (Severance cut mild steel)
After Flow Time
Dimensions
PLASMA 50HF
220/240V 50/60Hz
32Amps
50A
20-50A
200V
60%
HF Pilot Arc Start
75PSI
18mm
24mm
10 Seconds
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.
Transport Unloading
Never underestimate the weight of equipment, never move or leave suspended in the air above people. Use
recommended lifting equipment at all times.
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 fro 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 leads 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 for machine. 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 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

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The PLASMA 50HF Plasma Cutters require a 240V 50/60Hz 1-Phase supply. It requires an 32A fuse. 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 a mains electrical supply
THIS MACHINE IS OF AN INDUSTRIAL SPECIFICATION AND MUST BEFITTED TO A
32AMP 240V MAINS INPUT - DO NOT RUN ON 13AMP PLUG –FAILURE TO RUN ON
CORRECT SUPPLY WILL IN-VALIDATE WARRANTY
Connecting to an Engine Driven Generator
If connecting this Plasma Cutter to an engine driven generator please ensure the
following
Minimum Generator KVA Output 12KVA 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 invalidate your
warranty.

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Connections for PLASMA 50HF
Rear Machine connections
Fig 1
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.
2. Air pressure input
Screw supplied PCL fitting into regulator ensuring no air leaks You can also fit other connectors to suit your needs
3. 2
nd
Earth connection
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
4. Mains input cable
Fit required plug as per your electrical installation
5. POWER On/Off Switch
Turns machine on and off, the switch illuminates when machine turn on

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Front machine connections
Fig 2
1.Earth / Work piece 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 work piece via the earth clamp.
2. FUSE
Pilot arc fuse
3. Torch power connector
Connect the main torch euro socket by locating and pushing in and the screw retainer clockwise until tight.
Note: The head of torch has a safety feature, the machine will not work if
protective shroud is removed.

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Controls and Settings
Fig 1
1. Air pressure gauge
This shows the air pressure as set by regulator at rear of machine. This should be set to 75PSI when the test
gas button is activated.
2. Amperage control knob
This adjusts the amperage (cutting power) from 20 to 50 amps Note: LED display will show cutting amperage
when you are cutting.
3. L.E.D amperage display
When cutting this shows the actual cutting amperage
4. Test Gas / Cutting selector switch
When in the up position this is test gas mode, when setting air pressure switch to test gas so you obtain actual
air flow cutting pressure When in the down position this is cutting mode, you can now
start cutting
5. Auto / Standard switch
From 2017 this option is no longer fitted to machine
6. Indication of too low air pressure
The led will be light up when the air pressure is correct and ready for cutting, if the air pressure is too low the
LED will go out and the machine will not work. Adjust pressure to correct 75psi in test gas mode, led will light
up and you can resume cutting.

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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 and the power light indicates and cooling fan is running
3. Set the function switch in the test gas position, air will flow from torch head, now set the air pressure in
gauge using adjuster on regulator on rear of machine to 70PSI, Once the correct air pressure has been set
press down the adjuster on air regulator and set the function switch to the cutting position
4. Ensure earth clamp is connected to work piece or workbench ensuring a good clean point of contact
5. Select cutting amperage knob to desired cutting power (the following guide lines will vary in accordance to
material grade, characteristics and user operation)
a. 20 Amps for up to 6mm clean cut on mild steel
b. 30 Amps for up to 9mm clean cut on mild steel
c. 50 Amps for up to 18mm 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 the pilot arc
and contact with the work piece and machine will automatically switch to main cutting power. Once you
come to the end of cut on work piece the machine will sense this and turn off main cutting power and pilot
arc will re-engage, to stop cutting release switch.
7. Getting correct amperage / cutting speed for desired job.
8. The combination of correct cutting amperage and travel speed can change per user; here are some tips on
obtaining optimum settings.
9. 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
10. Cutting arc is erratic and work is being cut all way through. You are traveling too slow or cutting with too high
amperage for work.
11. 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.
12. 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 you probably need to 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. Fit new cutting tip if required if cutting hole is distorted or an angled cut happens replace the cutting tip.
7. Refit white ceramic shield cup by screwing on hand tight
8. 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
2. Failure to maintain plant can void manufacturer’s warranty.
3. Inspect input and output cables & hoses for fraying and cuts, replace if damaged present
4. Keep cutting torch and earth cables in good condition
5. Clean air vents to ensure proper air flow and cooling
6. 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 Pilot Arc
Check condition of torch consumables and replace if worn
Check pilot arc protecting fuse on front panel of machine and replace if blow – If fuse keeps blowing contact
R-Tech for repair / replacement torch
Please ensure machine is switched off before checking fuses
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 cutting - 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 to slow travel speed or to much cutting power, increase
speed of cut or reduce cutting amperage. (When machine senses no metal left to cut it will switch of main cutting
power and switch on HF pilot arc, this is the HF pilot arc restart)
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 torch consumables as per instructions earlier in this manual

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Plasma Torch Consumables parts list
Part No.
P50L-EL
P50L-CT1
P50L-RN
P50L-SS
Plasma 50HF
Electrode
Cutting tip
Retaining nozzle
Stand off spring
Double pointed spacer
Gas distributor
P50L-DPS
Torch head assy P50L-THH
Torch Complete Hand Held 6M P50L-6MHHT
P50L-GD
LT70 TYPE TORCH

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Wiring Diagram

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