Tweco 400 XT Ultra-Cut Plasma Cutting System With Automated Gas Control - Manual (Page 189)

ULTRA-CUT 400 XT
Manual 0-5306 APPENDIX A-65
Things that can cause Input Voltage Fault codes:
1. Intermittently having the power drop out on one or more phases for at least 1 ms. a longer term loss would more likely
trigger a different fault. If it’s the incoming power it would be likely not always be the same inverter.
2. Phase missing or intermittent to a specific inverter the fault would always call out that inverter.
3. Intermittent connections on the fault signal internal to the inverter.
247-252 Inverter Fault
Once the input contactors close applying voltage to the inverters several tests are performed. The Inverter Fault signal latches
on so even if the cause has gone away you can see that there was a fault as indicated by red LED D1, INV FLT on the inverter
Control & Fault PCB. It is reset by applying start signal or cycling power. If the fault is still present it will come back on.
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 (D6) 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 (380-480V 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(+) & 4(-) of the inverters 30 pin ribbon cable. If there is not a fault you should read
5-6V between the two pins. If INV_FLT is true voltage on pins 3 & 4 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 & 400A 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 403 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.