Tweco 200 XT Auto-Cut 400V - Manual (Page 142)

AUTO-CUT 200 XT
A-�0 APPENDIX Manual 0-5284
4. If the incoming voltage is OK and the problem persists it may be System Bias, CCM or connection between
J62 and J27.
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 toler-
ance.
• 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.