Tweco 400 Ultra-Cut(May 2014) User Manual
Page 201
ULTRA-CUT 100 XT/200 XT/300 XT/400 XT
Manual 0-5302
APPENDIX
A-73
238
System Bias voltage identification is invalid.
At power up the System Bias board measures the input voltage and sends signals to the CCM indicating which range of
voltage it has detected. See section 231-236 for details. If one of the 3 voltage ranges, 208-230V, 380-415V or 480V isn’t
identified then both ID signals are high resulting in an invalid signal.
Possible causes:
• Unit is connected to voltage below the 208-230V range or above the 480V range. (unlikely unless there is a problem
with the incoming voltage.)
• Defective System Bias board
• Bad connection between System Bias output J62 and CCM input J27 on the I/O board.
• Defective CCM
Troubleshooting:
1. Measure all 3 phases of the input voltage and confirm they are within the tolerance specified in the unit manual.
2. Refer to section 231-236 Inverter VAC Mismatch and perform troubleshooting in step 1.b. If the 2 signals don’t match
the incoming voltage, if both are high, then the System Bias is defective.
3. If step 2 was OK make the same measurement at J27 on the CCM I/O PCB. If OK here the CCM is defective. Otherwise
inspect the connections at J62 and J27.
239
AC Voltage High
Voltage OK -- At power up the System Bias board measures the input voltage and determined if it is within the range of volt-
age set by the J16 jumper. See section 231-236 Inverter VAC Mismatch Troubleshooting step 1.a for details of the jumper.
Normally when the input voltage is OK the System Bias board turns on a relay K1 on the left die of the board to apply power
to the T1 Auxiliary transformer. D44, a green “Transformer ON” LED, will light when K1 is energized. T1 provides power to
the gas controls and the TSC 3000 as well as the pumps and fans.
Voltage High -- If the AC voltage is determined to be too high it lights D4, ACV HIGH, a red LED on the System Bias board,
and sets the signal “AC V HIGH b” on J62-6 to a “high” about 24VDC (normal for a “low” here is 10-14VDC). To prevent
the possibility of excessive voltage applied to several items (gas controls, pumps, fans etc.) K1 is opened removing power
from T1 and D44 goes off. If it’s more than a momentary glitch the gas controls and the TSC 3000 (if used) will reset. Com-
munication with the cutting table may be interrupted. With the DFC 3000 Auto Gas Control and perhaps the cutting table
control, the process will have to be reloaded.
D4 is on and the signal “AC V HIGH b” is high only while the voltage is actually high. The signal “AC V HIGH b” does not
latch on.
If the fault is E239 that means it is currently active, that is, currently detected as being too high. If it’s L239 that means the
voltage too high previously but it is not too high now. Applying START will clear the fault unless it becomes active again.
The voltage that triggers an AC Voltage High fault is above 550V for 480VAC line; above 470V for a 380, 400 or 415V nominal
line; above 270V for a 208 or 230VAC line.
Possible causes:
• Incoming voltage is or was too high.
• Bad connection at J62 or J27
• Bad connection at J61 jumper
• System Bias board defective
• CCM defective.
Troubleshooting:
1. If the fault is L239 applying START will clear the fault unless it becomes active again. An occasional problem may be due
to incoming voltage swells (voltage increases lasting from ½ cycle to as much as a minute). Usually, if the plasma is at
fault the problem will be present all the time.