Tweco 300 XT Auto-Cut 400V - Manual (Page 135)

AUTO-CUT 300 XT
Manual 0-5290 APPENDIX A-53
Possible cause for work current to low.
• All the above plus a short to chassis caused by:
o User installed equipment connect behind the current sensor that makes a connection to work or earth
allowing current flow to bypass work sensor.
o Inverter + output shorted to chassis.
Troubleshooting:
1. For current too low due to a short disconnect work lead from back of unit. Check for continuity to chassis,
there should be none. Inspect for incorrectly connected user equipment.
2. If no shorts were found or if fault was current signal too high see section on code 207 for detailed description
of the power and signal paths for the work lead current sensor.
3. In the section on code 207 for Relay PCB it describes measuring the work current sensor signal when there
is no current. The signal should be zero and we assume it is or else you should have gotten the 207 code. If
the zero current signal is correct but there is an error while cutting, measure the signal on the 40pin ribbon
cable (Relay board J4 to CCM J23) pins 27 (-) & 28 (+). The signal voltage should equal the cutting current
* 0.0266. For example for 100A (100*0.0266) =2.66V.
• If this signal is correct the fault is the CCM
• If it’s not correct the error may be in the Relay board or sensor. Follow the instructions for code 207 to
measure the voltage to and signal from the current sensor at J1 on the Relay board. The signal voltage
should equal the cutting current * 0.0133. For example for 100A (100*0.0133) =1.33V. For 400A would be
400*0.013 3= 5.33V.
• If power and signal are correct Relay board is faulty. If not correct the HCT1 work current sensor is bad.
212-223 Incorrect output from an inverter section.
Work current high or low due to wrong output from one inverter section. Individual code indicates which section.
Causes may be:
• The named inverter section output connector, J102 A or B, is not plugged in or is damaged.
• Ribbon cable with bad connection, perhaps not fully locked in place at either the inverter or the CCM.
• Defective inverter section.
Troubleshooting:
1. If it reports the current of an individual inverter section is too high, the problem is the inverter.
2. If the report is current too low (which included no current) check the connections.
3. The ribbon cable for the first inverter section (IM#1A) must connect to that section only but if there are 2
additional sections, unit is 200A or greater, swap the ribbon cable going into those sections.
a. If it now reports a different section as bad, the one whose cable was moved, then the original section was
bad.
b. If it still reports the original section the ribbon cable or the CCM is bad (unlikely).
c. Swap both ends of the ribbon cable with one next to it. If still reports the original section then the problem
is with the CCM if not then it’s the ribbon cable.
4. If it’s the first inverter section or it’s a 100A unit so there’s no other inverter to swap cables with, replace the
inverter.
Additional hint: Inverter control PCBs have a green LED, D24, PWM ON, that lights when that section is enabled
and has a demand signal. The LED brightness is relative to the output so may be very dim if output is low. If
that LED doesn’t light may indicate a defective inverter (control board).