Tweco 400 XT Ultra-Cut Plasma Cutting System - Manual (Page 172)

ULTRA-CUT 400 XT
A-�� APPENDIX Manual 0-5275
Things that cause an inverter fault:
• One or more of the local bias supplies (+/-12VDC) failed or out of spec. Green LEDs on Cap Bias board labeled +12V
(D13) & -12V (D�) indicate the supplies are present but not necessarily that they are in tolerance.
• Input capacitor voltage imbalance indicated by D3 CAP IMBALANCE LED (red) on left side of main inverter board.
Applies to units with series connected capacitors (3�0-��0V units).
• Too much current in the main transformer (switching transformer) primary, D32, PRI OC LED (red), on inverter control
board.
INV_FLT is a differential signal on pins 3(+) & �(-) of the inverters 30 pin ribbon cable. If there is not a fault you should read
5-�V between the two pins. If INV_FLT is true voltage on pins 3 & � will be less than 2V.
253-258 Inverter Over Temperature.
Each inverter section (IS) contains one or more temperature sensors. If any of these detect an over temperature condition
it activates the signal “OVERTEMP_FLT going to the CCM over the inverter sections ribbon cable. Inverters semiconductors
(transistors and diodes) are liquid cooled. Anything that increases the coolant temperature too high can cause overheating
of the inverters. The inverters magnetics (transformer & inductors) are air cooled by the same fan(s) that cool(s) the liquid.
Possible causes:
• Cooling fan(s) not operating.
• Disrupted air flow.
• Defective inverter module.
• Inverter Ribbon cable bad connection.
• Defective CCM.
Originally 100 and 200A units had 2 smaller fans while 300 & �00A used a single larger fan along with a larger radiator. More
recently, the single larger fan may be used in the 100 & 200A as well.
Troubleshooting:
1. Confirm that air is exhausting from both the top (top fan)and bottom (bottom fan of units with 2 fans) of the 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. Refer to section for code �03 for troubleshooting defective fans.
!
WARNING!
Fan blades can be moving and accidental contact with a mirror or other inspection devise can cause personal injury
or damage to the machine.
2. Leaving the side panels and cover off, especially the left lower side or the top cover will reduce the air flow. Also if the
radiator fins become clogged with dust it will reduce air flow. Clean the radiator periodically by blowing air into it to clear
dirt from the fins.
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 �0 deg C we will get one or more of
the high ambient codes, 252-2��. 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.