Tweco 400 XT Ultra-Cut Plasma Cutting System With Automated Gas Control - Manual (Page 190)

ULTRA-CUT 400 XT
A-66 APPENDIX Manual 0-5306
259-264 Inverter Over Temperature due to high Ambient.
The CCM measures the ambient temperature where the cooling air enters the louvers on the left side of the front panel. If
an inverter goes over temperature and we have determined that the ambient exceeds 40 deg C we will get one or more of
the high ambient codes, 252-264. The sensor, TS2, is a NTC (Negative Temperature Coefficient) resistor whose resistance
varies with temperature. It is mounted on the inside of the front panel next to the louvers on the left. To access it requires
removing one or more of the inverter modules. If the ambient is high but no inverter is too hot there is no fault.
Possible causes:
• Ambient is too high.
• Cooling fan(s) not operating.
• Disrupted air flow.
• TS2, Ambient temperature sensor, shorted (very unlikely) or otherwise defective.
• Defective Relay board.
• Defective CCM.
• Defective Relay board.
Troubleshooting:
1. If room temperature exceeds 40 deg C, cool the room, or operate the unit at reduced duty cycle or lower current.
2. Confirm that air is exhausting from opening in the right side panel. As the fan(s) are behind the radiator it’s hard to see
them to confirm they are turning but perhaps you can use an inspection mirror. Be careful not to get the mirror or your
hands into the blades. 100 & 200A units have 2 smaller fans, 300 & 400A have one larger one.
3. It is unlikely these high ambient temperature codes would be set before some other temperature related code but just in
case we’ll note that leaving the side panels and cover off, especially the left lower side or the top cover will reduce the air
flow. Also the radiator fins clogged with dust will reduce air.
4. To test TS2 remove J2 from the Relay board and measure the resistance between pins 4 & 6 of the J2 harness connector.
The resistance varies from about 33K ohms at 0 degrees C to about 12K ohms at 20C to 5.3K ohms at 40C.
5. If TS2 is within the correct range the problem may be with the Relay board or the CCM.
a. The output from the relay board going to the CCM is on pin 30 of the 40 pin ribbon cable (J4 of Relay board to J23
of the CCM I/O board). It is an analog voltage that should range between 0.44V at 0 deg C to 1.6V at 40C. If it is
confirmed that the room ambient is not above 40C and Ambient temperature signal at pin 30 is higher than 1.6V then
the Relay board is defective.
b. If Ambient temperature signal at pin 30 is OK, less than 1.6V, and the room ambient is not above 40C then the CCM
is bad.
265-270 Inverter No Input Power
There are several digital signals on the ribbon cables between the inverter sections and the CCM that involve some level of
voltage. These include AC_INPUT_FLT\, INVERTER _FLT\, OVERTEMP_FLT\ and POWER_PRESENT. Normally all of these
should be high. Before power is applied to the inverter modules the CCM has already performed a continuity check to see if
that section is in place and it’s ribbon cable connected (code 224 & 237). As soon as power is applied to the inverter modules
the CCM checks these 4 signals and, having already confirmed there is an inverter whose ribbon cable is connected. If it
finds none of the signals have voltage, it assumes there is no power into the section or something is wrong with that inverter
section’s bias power.
Possible causes:
• The 3 input phases, J103-105 to that inverter section not connected.
• The circuit breaker CB2 providing the 120 VAC to the contactor (and Remote Arc Starter) has tripped.
• The contactor powering that section (and others) defective.
• Relay board defective.
• Inverter defective.
• CCM defective.