Tweco 400 Ultra-Cut(May 2014) - Manual (Page 209)

ULTRA-CUT 100 XT/200 XT/300 XT/400 XT
Manual 0-5302 APPENDIX A-81
402 Low coolant Flow
The flow switch FS1 is positioned in series with the radiator where it measures the flow returning from the torch. The flow
switch serves two purposes, one to insure there is adequate flow for cooling needs and two, it insures the torch consum-
ables are in place so the negative output of the power supply is not exposed. This function is called “Parts in Place” or PIP.
The output cannot be enabled if parts are not in place. The normally open flow switch requires 0.7 GPM (2.65 liter/min.)
+/- about 10% to close.
When the system is turned on and enabled and fails to achieve proper coolant flow after 4 minutes code 404 will be set.
Getting code 402 means it initially had enough flow but something has caused the flow to be reduced. Listed here are things
that might happen during cutting to cause reduced flow. For other causes like component failures refer to code 404.
Possible causes for low flow:
• Coolant filter clogged.
• Flow bypass valve incorrect adjustment or defective. Call the factory for instructions.
• Defective pump.
• Coolant supply or return hose twisted or pinched reducing flow.
If coolant flow is not low but code is being set, possible causes:
• Flow switch disconnected or defective.
• Relay PCB.
• CCM.
Troubleshooting:
1. First note whether the fault is an “E” meaning it’s currently low or an “L” meaning it was low but isn’t now. Flow that
remains low could indicate a failed component or a blockage such as clogged filter or pinched hose. It also means you
should be able to measure the flow to determine if it is really low or the sensor has a problem.
2. First recycle power. If flow is still low or a component is defective the code should change to 404. Go to that section for
further troubleshooting.
3. If after recycling power there is no code, continue cutting to see if it occurs again. Take note of when it occurs, for example
if it’s with the torch at one end of the table, perhaps the leads get pinched there? In any case go to code 404 section for
more information.
403 Coolant overheated.
TS1 is a linear negative temperature coefficient (NTC) resistor sensor attached to the brass fitting at the exit of the bypass
valve. Here we determine the coolant being supplied to the torch is below the required temperature which is currently 75
deg C (167F). The radiator is on the lower right side of the unit. The fan(s) are behind it and blow out through the radiator.
100A & 200A units may either have 2 smaller fans or one larger one. The 300 & 400A units have one larger one.
Fans operate during cutting and for 4 minutes after last cut then shut off. Exception is AC 200 XT where the fans are on
whenever power is on. The external heat exchanger, HE400, fan is thermostatically controlled so it only comes on when
coolant is over 60 deg C. It will shut off when the other fans shut off.
Possible reasons for coolant overheated:
Coolant fan(s) failed or defective fan control relay MC2.
• Radiator fins clogged with dirt.
• Duty cycle exceeded (ambient temperature above 40 deg C and operating at high duty cycle).
• Operating with an object placed in close proximity to the air outlet (right side of the unit) or the front panel inlet open-
ings.
• Operating for extended time with right lower side panel removed.
• Defective Relay board.
• Defective CCM.