Tweco 400 Ultra-Cut(May 2014) - Manual (Page 203)

ULTRA-CUT 100 XT/200 XT/300 XT/400 XT
Manual 0-5302 APPENDIX A-75
a. If the incoming voltage is OK and D14, ACV LOW, is on or the signal “AC V LOW b” on J62-10 is “high” (about 24VDC,
relative to TP1 or J62-8 ) the System Bias board is defective.
b. If D14 is not on and signal “AC V HIGH b” on J62-10 is “low” (about 10-14VDC, relative to TP1 or J62-8) then System
Bias is OK and problem is in the CCM.
c. If J62-10 is near zero volts there may be a bad connection between J62-10 and J27-10 or J62-7 and J27-7.
241-246 Inverter Section Input Voltage Error.
The System Bias board checks for input voltage high, low or missing a phase from the power coming in from the power cord.
It is unlikely but not impossible that a problem with the incoming power could result in 241-246 codes. The 241-246 codes
more likely point to problems with the power into or within a single inverter section or in the case of missing phase it may
be the contactor that supplies up to 3 inverter sections.
Once the input contactors close, applying voltage to the inverters, they test for input too high or too low and for missing
phase. When the input voltage is in the correct range, a green LED, D4, named READY, lights on the left side of the main
inverter board. If D4 is not on, either the input voltage is out of range or the inverter is defective.
You can still get the 241-246 code with a missing phase with the READY LED on. The LED will be going on and off rapidly
but appears to the eye to be on. In this case you can measure the signal on the ribbon cable. The signal previously called
READY is now called AC_INPUT_FLT. It is a differential signal on pins 1(+) & 2(-) of the inverters 30 pin ribbon cable. If the
AC input is correct you should read 5-6V between the pins. If AC_INPUT_FLT is true voltage on pins 1 & 2 will be less than 2V.
Some of the other faults such as Inverter Fault and Over Temperature also set the AC_INPUT_FLT (not Ready). However, they
will latch on associated LEDs or set different fault codes. In the event of an Input Voltage Fault the CCM does not remove
power from the inverter.
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.