Hwayuan Electric LGK-120HD User manual

LGK-120/200/300/400HD
AIR PLASMA CUTTING MACHINE
MANUAL
INSTRUCTION
(PLEASE READ IT CAREFULLY BEFORE OPERATION)

Safety Depends on You
HUAYUAN arc welding and cutting equipments are designed and built with ample safety consideration. However, proper
installing and operating can ensure your safety.
DO NOT INSTALL, OPERATE OR REPAIR THIS EQUIPMENT CASUALLY WITHOUT READING THIS MANUAL THROUGHOUT.
Special Notes (Very Important):
1. Pay attention to avoiding the machine falling down when it is placed on the gradient ground.
2. It is forbidden to unfreeze the pipeline by the cutter.
3. The shield rank of this series of cutter is IP21S, so working in rain is not suitable.
4．The cutter has external static characteristic with rated duty cycle 100%, which means the machine can work
continuously at the rated cutting current. The machine has the function of thermal protection. When the internal
temperature exceeds a set temperature, thermal protection moves on and the abnormity indicator lamp on the panel turns
ON, then there is no output in cutter. The machine can become normal and work only after the internal temperature drops
down and the abnormity indicator lamp on the panel turns OFF.
Purchase Date：_______________
Serial Number：_______________
Machine Model：______________
Purchase Place：______________

C a u t io n s
Arc and arc rays can hurt.
All performing welding workers ought to have health qualification from the authority organization to prevent you and
others from arc radiation and burn. It should be prevented for children to enter into dangerous area as well.
Be careful reading the following important items and the welder safety byelaw from the authority organization. Be sure
that qualified professionals perform all installation, maintenances and repair procedures.
1 Electric shock: The welding circuits are not insulated when welding. If you touch the two output
electrodes of the machine with your bare skin at the same time, it will lead to electric shock, sometimes
even fatal dangers. Users need to follow the items below to avoid electric shocks:
If possible, lay some insulating materials, which are dry and large enough, in your working field. Otherwise,
use the automatic or semiautomatic welding machine, DC welding machine as possible as you can.
Components in the automatic and semiautomatic welding machine such as the welding wire reel, feed wheel,
contact tip and welding head are all electric components. .
Always be sure the machine has been connected perfectly to the work piece with the work cables and should
be as close as possible to the working area.
The work piece should be grounded perfectly.
Make sure that the insulating material of the electrode holder, the grounding clamp, the welding cable and
the welding head are not affected by damp, mildewed or spoilt, and be replaced momentarily.
Never dip the electrode in water for cooling.
Never touch electric components of two welding machines at the same time, because this voltage is
supposed to be two times of welding voltage while the grounding mode is not clear.
While working high above the ground or other places having the risk of falling, please be sure to wear safety
belt to avoid losing balance caused by electric shock.
2 Arc: Use an arc welding mask to protect your eyes and skin from sparks and the rays of the arc, pay
special attention to the filter glass, which must be conformable to the national standard.
Use clothing made from durable flame-resistant material or sailcloth to protect your skin
from hurting by the arc rays.
Remind other nearby personnel before working lest arc rays hurt them by accident.
3 Fumes and Gases: Welding may produce fumes and gases hazardous to health. Avoid breathing these
fumes and gases. While working in limited room, use enough ventilation and/or exhaust to keep fumes
and gases away from the breathing zone, or use the respirator. Do not weld at the same time when
using of degreasing, cleaning or spraying operations. The heat and rays of the arc can react with these gases to form
phosgene, a highly toxic gas,
Some protective gases used in welding might displace the oxygen in the air, and can lead to hurt or even
death.
Read and understand the manufacturer’s instructions for this equipment, and validate the health certification
of consumptive materials, make sure they are innocuous.
4 Spatter: Spatter can cause fire or explosion.
Remove fire hazards from the welding area. Remember that spatter from welding can easily
go through small cracks and touch fire hazards. Protect all kinds of lines going though welding
area, including hydraulic lines in the wild.

Where compressed gases are to be used in the field, special precautions should be used to prevent explosion.
When welding stops, make certain that no live part is touching the work piece or the work stage. Accidental
contact can create a fire hazard.
Do not weld containers or lines, which are not proved to be innocuous.
It is very dangerous to heat, cut or weld tanks or containers at entry holes. Does not start work until the
proper steps have been taken to insure that there is no flammable or toxic gas.
Spatter might cause burn. Wear leather gloves, heavy shirt, cuffless trousers, high shoes and a cap over your
hair to prevent from burning by spatter. Wear the ear shield when performing sideways or face up welding. Always
wear safety glasses with side shields when being in a welding area.
The welding cables should be as close to the welding area as possible, and the short, the better. Avoid
welding cables going through the building framework, lifting chains, AC or DC cables of other welding machines and
appliances. The welding current is strong enough to damage them while having short circuit with them.
5 Cylinder: Damage of it might cause explosion.
Make sure that the gas in the storage cylinder is qualified for welding, and the
decompression flow-meter, the adapter and the pipe are all in good condition.
Make sure that the installation of cylinder is by the wall and bundled tightly by a chain.
Be sure to put the cylinder in the working space with no crash or shake, and far from welding area.
It is forbidden to touch cylinder with the welding clamp or the work cables.
Avoid facing the cylinder while installing the decompression flow-meter or the gasometer.
When not working, please tighten the valve.
6 Power: (For electrically powered welding and cutting equipment) Turn off input power before
installation, maintenances and repair, so that avoid accident.
HUAYUAN welding equipment is Ι class safeguard equipment; please install the equipment
in accordance with the manufacturer’s recommendations by specific persons.
Ground the equipment perfectly in accordance with the manufacturer’s recommendations.
7 Power:(For engine driven welding and cutting equipment)
Work in ventilated place or outdoors.
Do not add fuel near to fire or during engine starting or welding. When not working, add fuel
after engine is cooling down; otherwise, the evaporation of hot fuel would result in dangers. Do not
splash fuel out of the fuel tank, and do not start the engine until complete evaporation of the
outside fuel.
Make sure that all the safeguard equipment, machine cover and devices are all in a good
condition. Be sure that arms, clothes and all the tools do not touch all the moving and rotating
components including V belt, gear and fan etc.
Sometimes having to dismantle some parts of the device during maintenance, but must keep safety
awareness strongly every time.
Do not put your hand close to fans and do not move the brake handle while operating.
Please remove the connection between the engine and the welding equipment to avoid sudden starting
during maintenance.
When engine is hot, it is forbidden to open the airtight cover of the radiator water tank to avoid hurt by the
hot vapor.
8 Electromagnetic: Welding current going though any area can generate electromagnetic, as well as the
welding equipment itself.
Electromagnetic would affect cardiac pacemaker, the cardiac pacemaker users should consult
one’s doctor first.

The effect of electromagnetic to one’s health is not confirmed, so it might have some negative effect to one’s
health.
Welders may use following method to reduce the hazardous of electromagnetic:
a. Bundle the cable connected to the work piece and the welding cable together.
b. Do not enwind partially or entirely your body with the cable.
c. Do not place yourself between the welding cable and the ground (work piece) cable, if the welding cable is by your
left side, then the ground cable should be by your left side too.
d. The Welding cable and the ground cable are as short as possible.
e. Do not work near to the welding power source.
9 Lift Equipment: carton or wooden boxes package the welding machines supplied by HUAYUAN. There
is no lifting equipment in its wrapper. Users can move it to the prospective area by a fork-lift truck, and
then open the box.
If having rings, the machine can be transited using rings. While HUAYUAN Welding Machine
Manufacture reminds users, there is possible risk to damage the welding machine. It is better to
push the welding machine moving in use of its rollers unless special situations.
Be sure that the appurtenances are all removed off when lifting.
When lifting, make sure that there is no person below the welding machine, and remind
people passing by at any moment.
Do not move the hoist too fast.

10 Noise: HUAYUAN Welding Machine Manufacture reminds users: Noise beyond the limit (over 80
db) can cause injury to vision, heart and audition depending on oneself. Please consult local medical
institution. Use the equipment with doctor’s permission would help to keeping healthy.

Content
MANUAL INSTRUCTION ................................................................................................................................... 0
1SUMMARY ..................................................................................................................1
1.1 MODEL DESCRIPTION.........................................................................................................1
1.2 FEATURES.........................................................................................................................1
1.3 USAGE.............................................................................................................................1
1.4 SYMBOL INSTRUCTION........................................................................................................1
2SAFETY AND ATTENTION .............................................................................................2
3WORKING ENVIRONMENT REQUIREMENTS .................................................................3
4TECHNICAL PARAMETERS ............................................................................................4
4.1 MAIN TECHNICAL PARAMETERS ...........................................................................................4
4.2 PLASMA GAS CONDITION ....................................................................................................4
4.3 EXTERNAL CHARACTERISTIC CURVE........................................................................................4
5BASIC PRINCIPLE .........................................................................................................5
6INSTALLATION AND OPERATION ..................................................................................6
6.1 MOVING AND LIFTING ........................................................................................................6
6.2 OPEN THE PACKING AND CHECK............................................................................................6
6.3 THE FIX AND INSTALLATION OF THE PLASMA POWER SOURCE......................................................6
6.4 THE CONNECTION OF 3PHASE INPUT POWER CABLE .................................................................8
6.5 THE CONNECTION OF COMPRESSED AIR AND THE OPERATION OF PRESSURE REGULATING FILTER (THE
FUNCTION OF PRESSURE REGULATING FILTER PLEASE CHECK THE BELOW FIGURE)......................................9
6.6 CONNECTION OF COOLING WATER (LGK-120HD DOES NOT HAVE THIS FUNCTION).......................9
6.7 THE CONNECTION OF OUTPUT TERMINAL .............................................................................10
6.8 THE CONNECTION OF CONTROL SIGNAL CONNECTORS (FOR CNC (AUTOMATIC)CUTTING
CONNECTION)............................................................................................................................11
6.9 THE CONNECTION OF WATER COOLING MACHINE INTELLIGENT COMMUNICATION INTERFACE (THERE IS
NO THIS INTERFACE ON LGK-120HD, WHEN LGK-200/300/400HD WORK WITH WATER COOLING,THIS
INTERFACE WILL BE USED)............................................................................................................12
6.10 PANEL AND IT’S FUNCTION INSTRUCTION..............................................................................12
6.11 PROTECTION FUNCTION INTRODUCTION...............................................................................18
6.12 OPERATION ....................................................................................................................19
7OPERATION AND SETTING .........................................................................................21
7.1 POWER ON SELF TEST .......................................................................................................21
7.2 THE AIR PRESSURE ADJUST AND DISPLAY ..............................................................................21
7.3 LIQUID FLOW DISPLAY (NOT ON LGK-120HD).....................................................................22
7.4 CUTTING CURRENT SETTING...............................................................................................22

7.5 SECONDARY MENU ..........................................................................................................22
7.6 TORCH MONITORING FUNCTION .........................................................................................23
8BRIEF INTRODUCTION OF THE CUTTING TECHNOLOGY...............................................24
8.1 MAIN CUTTING PARAMETER AND THE TECHNICAL BASIS ..........................................................24
8.2 CUTTING BURR ELIMINATING ISSUE .....................................................................................26
8.3 CUTTING TABLE ...............................................................................................................28
9PACKING LIST ............................................................................................................34
9.1 PACKING LIST OF PLASMA POWER SOURCE ............................................................................34
9.2 SYSTEM PACKING LIST .......................................................................................................34
10 MAINTENANCE ......................................................................................................34
11 TROUBLESHOOTING...............................................................................................35
11.1 PLEASE FIRSTLY CHECK FOLLOWING ITEMS IF ANY TROUBLES .....................................................35
11.2 ORDINARY TROUBLESHOOTING AS FOLLOWING SHEET.............................................................36
11.3 SOME POPULAR COMPONENTS SHEET AS BELOW ................................................................... 37
12 ATTACHED DIAGRAM 1：MAIN CIRCUIT DIAGRAM.................................................39

1
1Summary
1.1 Model Description
L G K-□□□ HD
Series code
Rated cutting current
Air medium
Cutting
Plasma arc cutting machine
1.2 Features
LGK-120、200、300、400HD series plasma cutting machine have below features：
100% (40℃) rated duty cycle, suitable for work in heavy industry;
Adopt gas pressure sensor, the cutting torch can be properly protected when the gas
pressure is too low;
Adopt liquid flow sensor, the cutting torch can be properly protected when the
liquid flow is too low, and the liquid flow is displayed on the display meter;
The gas pre-flow time, gas post-flow time, current up-slope time can be separately
set according to the torch cable length;
The plasma gas pressure can be adjusted on the panel, the pressure is displayed on
the meter, friendly operation;
There is digital communication connector, can be connected with different
automation equipment;
With torch monitoring function, warning to change the consumables, to longer the
torch working life;
Intelligent fan is used to reduce the dust;
With automatic protection of over-heating and lack-voltage.
1.3 Usage
It is suitable for cutting kinds of metal materials like low carbon steel, alloy
steel and non-ferrous metal and is widely applied in the manufacturing of boiler
pressure container, chemical container, industrial power station construction,
metallurgy, aerospace industry, automobiles, building an so on.
1.4 Symbol Instruction

2
Read the manual carefully
Dangerous voltage
Over-heat
Input voltage
Power abnormal
Output current
Air pressure
Voltage output
Coolant liquid input
Voltage input
Coolant liquid output
Cutting
Plasma torch
Check gas
Lock
Ground lead
Unlock
Protection ground lead
Water cooling
Remote control
Air cooling
Increase/ Decrease
The nozzle connection of
plasma torch
Plasma gas and torch
electrode
Current
Coolant liquid and torch
electrode
2Safety and attention
Please follow the notes for the safety of you and others.
It is forbidden to unfreeze the pipe line by cutting power or other usages except
for cutting.
The cutter casing should ground reliably. Please make sure the grounding bolts
of power ground reliably in case of electric shock.
Cutter is the equipment with high voltage. Please wear insulated protective

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shield when cutting.
When exchanging torch and wearing parts, please turn off the supply power
first.
Protective shield should be worn.
In order to avoid any hurt to eyes from ultraviolet radiation and strong light and
to skin from spatter, please wear protective shield according to related rules and
regulations of labor protection.
It is forbidden to inhale harmful gases.
The fumes and gases produced during cutting is hazardous to health. Please
wear protective shields and install aerator according to related rules and
regulations of labor protection.
Cutting cannot proceed in closed container.
The work-piece just after being cut is at high temperature. Please prevent from
scald.
Protective gas cylinder and air compressor must be placed in a fixed position
and prevented from collision.
Cutter and cutting place should be far away from flammable materials.
Prevent foreign bodies from entering inside the machine. And protect the cable
from sharp materials.
Protect the machine from fall or collision.
In case of fall or collision, it can be used only after professional checking.
In the surface or inside of the cutting work-piece, there should be no flammable
and explosive materials or chemical materials harmful to human.
Installation and repair person must have state-authorized electrician operation
certificate.
Cutting operation person should read this manual carefully and know the
operation method well.
3Working Environment Requirements
If not reach the flowing conditions, the cutting capacity may not reach
the technical specification values
1) Please use the machine in a clear place without any of dust, corrosive gas and
inflammables and explosives; Do not use it in open air and rain;
2) Required air relative humidity should ≤90％(at 20℃)，40℃≤50％(at 40℃)；
3) Environment temperature range should be at-10℃～40℃;
4) The coolant liquid cannot be frozen when use;
5) Any metal materials cannot be put on or insider the power source;
6) Keep the machine away from the wall of some other closure things at least 30cm,
two machines distance at least 30cm.

4
7) Use it under altitude lower than 1000m.
4Technical Parameters
4.1 Main Technical Parameters
LGK-120HD
LGK-200HD
LGK-300HD
LGK-400HD
Rated input voltage
3～380/415V 50/60Hz
Rated input capacity
21.23VA
46.5kVA
70.42kVA
92.34kVA
Rated output current
120A
200A
300A
400A
Rated output voltage
128V
160V
200V
200V
Rated duty cycle
100%
100%
100%
100%
Open circuit voltage
308VDC
319VDC
370 VDC
370VDC
Current adjust range
30～120A
40～200A
60～300A
60～400A
QualityCuttingThickness
(Carbonsteel,manualcutting)
0.3～25mm
1～45mm
1～50mm
1～60mm
Max.CuttingThickness
(Carbonsteel,manualcutting)
45mm
65mm
80mm
90mm
Plasma gas
Compressed Air
The working plasma gas
pressure
0.3～0.5MPa
0.4～0.6MPa
0.4～0.6MPa
0.4～0.6MPa
Torch cooling mode
Air Cooling
Air Cooling / Water Cooling
Arc striking mode
HF
Insulation grade
F
Protection grade
IP21S
Dimension mm(L×W×H)
675×320×605
863×385×800
985×445×910
1015×445×910
NET WEIGHT
46kg
86 kg
129 kg
148 kg
4.2 Plasma gas condition
Gas pressure range：0.5MPa～0.7MPa
Gas supply pipe compression strength：≥1MPa
Gas supply pipe inner dimension：≥Φ8
Gas flow：≥180L/min
Filter the water in the gas, then feed into the plasma
4.3 External characteristic curve
Model
Parameters

5
5Basic Principle
The control circuit of this cutting machine adopts advanced electronic part IGBT as
the main inverter switch component. Three-phase AC power is converted to 20KHz
high-frequency DC current after being rectified by three phase rectifier. Then under the
function of IGBT inverter the DC current is inverted to AC high frequency current, which
is inverted to DC current after experiencing voltage reduction in high frequency
transformer, current rectifying in fast recovery diode. This DC current is filtered through
reactor, and the output cutting current is obtained. Control circuit can control output
current by controlling driven pulse width. The real time cutting current, which is
obtained through current sensor connected to output terminal in series, is used as
negative feedback control signal. After comparing with current adjusting signal, the
negative control signal is sent to PWM adjusting integrated circuit, then a controlled
driving pulse is output to control IGBT. Thereby a constant output current can be
maintained, and a steep dropping & constant current external characteristic is obtained.
Striking arc adopts high-frequency striking model. The main circuit refers to appendix
figure, and principle diagram of control circuit is shown as below figure：

6
6Installation and operation
6.1 Moving and lifting
Power source should be shut off before moving the cutter；
The cutter bottom should be kept downwards during transportation. It is forbidden
to have cutter placed transversely or upended；
When lifting, it must be lifted vertically；
During the long-distance transportation, it must prevent the cutter from raining and
moving back and forth inside box. Shock absorption foam should be placed around
cutter；
6.2 Open the packing and check
1) Check the machine and packing according to the packing list, of there is any damage,
please try to contact the supplier
6.3 The fix and installation of the plasma power source

7
LGK-120HD Dimension and installation size
LGK-200HD Dimension and installation size

8
LGK-300HD Dimension and installation size
LGK-400HD Dimension and installation size
6.4 The connection of 3 phase input power cable
Power supply condition
1) Voltage fluctuation≤±10％；
2) Frequency fluctuation≤±1％；
3) Unbalance rate of three phase voltage≤5％；
4) The power supply condition please check the chart below:
Model
The sectional area of
input copper cable
(mm2)
The sectional area
of ground cable
(mm2)
Fuse (A)
Contact capacity
(A)

9
LGK-120HD
≥6
≥6
60
63
LGK-200HD
≥16
≥16
125
125
LGK-300HD
≥25
≥25
160
150
LGK-400HD
≥50
≥50
200
250
The connection of power lead
Use eligible cables and sockets to connect it, and must be operated by a qualified
electrician.
Connection of ground cable
Connect it to ground on marking of the machine body), the sectional area
must match the requirements in above form, to ground firmly. Ground connecting
method should follow state standard.
6.5 The connection of compressed air and the operation of pressure
regulating filter (The function of pressure regulating filter please check the
below figure)
Pic 7：Air filter regulator
1) The compressed gas should meet the requirement mentioned in point “4.2 Plasma
gas conditions”. Connect the gas pipe with the gas inlet of air filter on the rear panel
and hoop it tightly.
2) The air filter regulator should be checked periodically. If the water level reaches
two-thirds of filter glass, it must be drained, or the cutting incision quality will be
effected. The gas supply valve should be closed during water draining, and Gas
Checking function is selected in panel. When the indicated valve of gas pressure
meter is zero, water will drain out from drainage mouth automatically.
6.6 Connection of cooling water (LGK-120HD does not have this function)
Connect the copper tip marked with “water inlet” on the rear side with water supply

10
pipe, and tighten it. Connect the copper tip marked with “Backwater” with water recycle
pipe, and tighten it.
Notes: when use air cooling torch, the torch selection switch on panel must be set to
air-cooled torch position, and the cooling water cannot be connected. The cooling
water is for cooling torch only, and cutter power source does not need water cooling.
6.7 The connection of output terminal
The connection of the torch
1) Connectors instruction
The pilot arc: to connect the arc striking wire of the torch;
Control: Pin 1 and 2 is start control, to connect the control switch of the torch.
Pin 3 and 4 is water cooling/air cooling. When use air cooling torch, short
connect the pin 3 and 4, when use water cooling torch, don’t connect the pin 3
and 4;
Air & Current output: the negative output connector of the machine is the
plasma gas output connector, the connector thread is M14×1.5;
Water & Current output: the negative output connector of the machine is the
cooling water output connector, to connect the water inlet of the water cooling
torch, the connector thread is M16×1.5;
Water Return & Current: the negative output connector of the machine is the
cooling water return connector, to connect the return water of the water
cooling torch, the connector thread is M16×1.5 (laevorotation);
Pic 8 The connectors of torch
2) The connection of air cooling torch (Please refer to the Pic 8 as above)
Firstly connect the torch air inlet cable connector with the copper tip marked with

11
Air & Current output on the front bottom panel; then connect the torch pilot wire
to terminal marked with Pilot arc on the front panel; Finally, connect the torch
control connector to the terminal marked with Control on the front panel and
screw down the nut;
3) The Connection of water-cooling torch (Not for LGK-120HD) (Please refer to the Pic
8 as above)
Firstly connect the torch cable connector (cooling water return) with the copper tip
marked with Water Return & Current on the front panel. Connect the torch cable
connector (cooling water output) with the copper tip marked with Water & Current
output on the front panel. Connect the torch gas pipe nut with the copper tip
marked with Air & Current output. then connect the torch pilot wire to terminal
marked with Pilot arc on the front panel; Finally, connect the torch control
connector to the terminal marked with Control on the front panel and screw down
the nut;
4) The requirements of control plug connection when customers use different torches
Use WS20J4TQ 4-pins plug;
Requirements on air cooling torch connection:
a) Connect the 1, 2 pin of 4- pins plug to switch control wire of cutting torch;
b) Short connect 3, 4 pin of 4-pins plug by gummed wire;
c) Pilot arc wire connects cold-press joint UT-8;
Requirements on water cooling torch:
a) Connect the 1, 2 pin of 4-pins plug to switch control wire of cutting torch;
b) The 3, 4 pin don`t connect any of wire;
c) Pilot arc wire connects cold-press joint UT-8;
5) Connection of cutting ground cable
LGK-120HD: Connect the fast connector of cutting ground cable with the
adapter base on the front panel and screw down it clockwise. The other end of
the cutting ground cable is firmly connected to work-piece.
LGK-200/300/400HD: Connect the cutting ground cable with the copper tip on
the front panel with nuts. The other end of the cutting ground cable is firmly
connected to work-piece.
6.8 The connection of control signal connectors (For CNC (Automatic)
cutting connection)
The socket model of the connector is : WS20K4Z, and the function for each wire pin is as

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following:
1) Connector pin 1 and pin 2 is signal output of success arc striking, it is one group of
contact terminal of relay, and its rated load capability is 0.3A/125VAC or 1A/30VDC.
2) Connector pin 3 and pin 4 is start control wire of the cutter, its starting method is
controlled by operating selection switch. Usually 2-Step is selected, that is, it starts
under short connection, and stops after cutting off. The two wire is used in parallel
with torch control socket pin 1, pin 2 on the front panel.
6.9 The connection of water cooling machine intelligent communication interface
(There is no this interface on LGK-120HD, when LGK-200/300/400HD work with water
cooling, this interface will be used)
The socket model of the connector is : WS20J7TQ, and the function for each wire pin is
as following:
1) Connector pin 3 and pin 4 is start control wire of the cutter, it is one group of contact
terminal of relay, it’s on closing status when the torch switch is on, and it’s on
breaking status when the torch switch is off. Its rated load capability is 0.3A/125VAC
or 1A/30VDC
2) Connector pin 5 and pin 6 is protection signal that water cooling machine output to
plasma cutter, when short connect the pin 5 and 6, there will be no current and
voltage output from the plasma cutter.
Special note: To confirm the good cooling performance, and lengthen the
consumable life, you’d better choose the water cooling machine from HUAYUAN.
6.10 Panel and it’s function instruction
Note: The title number is corresponding to the number on the Pic 9, for example,
the “1）” is corresponding to “1”on Pic 9.
1) The gas pressure adjusting valve: to adjust the gas pressure, pull it out and contra
rotate to reduce the gas pressure, rotate it clockwise to increase the gas pressure;
2) Torch lock function indicator: Press “OPERATE” key, when this indicator is on, mean
it’s on “torch lock” status;
3) Torch unlock function indicator: Press “OPERATE” key, when this indicator is on,
mean it’s on “torch unlock” status;
4) ”OPERATE” key: To choose the “torch unlock” and “torch lock” function. When it
turns on “torch lock”, the torch switch should be pressed in the process of cutting,
and the cutting stops after loosening the switch. When it turns on “torch unlock”,
press the torch switch and loosen it, the cutting starts to work, and the stops after
pressing the switch again;

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5) Current display indicator light: Press “DISPLAY” key, when this indicator is on it,
means the digital displaying meter (Number 8) is displaying the current value. When
there is starting signal (No.12 indicator light is on), the output current value is
displaying, when it’s not starting, the pre-setting current value is displaying;
6) Plasma gas pressure displaying indicator light: Press “DISPLAY” key, when this
indicator is on it, means the digital displaying meter (Number 8) is displaying the
plasma gas pressure value;
7) Water coolant flow displaying indicator light: Press “DISPLAY” key, when this
indicator is on it, means the digital displaying meter （Number 8）is displaying the
water coolant flow value;
8) Digital displaying meter: Displaying pre-set cutting current, real current, plasma gas
pressure, parameters on secondary menu and error code;
9) The “DISPLAY” key: to swift the different displaying function of “A”/ “Mpa”/“L/min”
(There is no “L/min” displaying function on LGK-120HD);
10) AIR PRESSURE indicator light：to indicate the status of plasma gas pressure.
If this indicator light is ON: means the plasma gas pressure ≥0.38MPa, it’s
normal.
The indicator light 0.3s on and 0.3s off (Quick flashing): means the plasma gas
pressure is in warning value range(0.3MPa≤air pressure＜0.38MPa ), now the
cutter can work, but the cutting quality may get bad, and the consumables may
burned faster;
The indicator light is off: means the plasma gas pressure ＜0.3MPa, now the
cutter stop working;
The indicator light 1s on and 1s off (Slow flashing): means the plasma gas
pressure was too low but back to normal now. And this slow flashing status will
keep 3 minutes. It’s normal.
11) COOLANT FLOW displaying indicator light (There is no this indicator on LGK-120HD):
to indicate the torch coolant flow status.
If this indicator light is ON: means the coolant flow ≥2.7L/min, it’s normal.
The indicator light 0.3s on and 0.3s off (Quick flashing): means the coolant flow
is in warning value range(2.0L/min≤ coolant flow＜2.7L/min), now the cutter
can work, but the consumables may burned much faster;
The indicator light is off: means the coolant flow ＜2L/min, now the cutter stop
working;
The indicator light 1s on and 1s off (Slow flashing): means the coolant flow was
too low (＜2L/min )but back to normal now. And this slow flashing status will