Tweco 400 XT Ultra-Cut Plasma Cutting System - Manual (Page 170)

ULTRA-CUT 400 XT
A-�2 APPENDIX Manual 0-5275
D� 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 ��0VAC line; above �70V for a 3�0, �00 or �15V nominal
line; above 270V for a 20� 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.
2. It is unlikely that an open connection on the J�1 jumper would result in a 239 fault, more likely to be a Voltage Mismatch
fault. However, if it’s intermittent at exactly the right time, perhaps not fully plugged in, it could possibly show up as 239.
Check J�1.
3. If the incoming voltage is OK and the problem persists it may be the System Bias board, the CCM or the connection
between J�2 and J27.
a. If the incoming voltage is OK and D� is on or signal “AC V HIGH b” on J�2-� is “high” (about 2�VDC, relative to TP1
or J�2-� ) the System Bias board is defective.
b. If D� is not on and the signal “AC V HIGH b” on J�2-� is “low” (about 10-1�VDC, relative to TP1 or J�2-�) then System
Bias is OK and problem is in the CCM.
c. If J�2-� is near zero volts there may be bad connection between J�2-� and J27-� or J�2-7 and J27-�.
240 AC Voltage Low
Refer to the first paragraph for code 239 for explanation of what should happen when the input voltage is correct.
Voltage Low -- If the System Bias board determines AC voltage is too low it lights a red LED, D1�, ACV LOW, and sets the
signal “AC V LOW b” on J�2-10 to a “high”, about 2�VDC (normal for a “low” here is 10-1�VDC). Power is not removed from
T1 as low voltage won’t damage anything, However, if it’s too low for too long, some things like contactors, AC solenoids,
the gas controls or TSC 3000 may stop working. A low voltage, if it’s low enough, may also light D3, the red Missing Phase
LED. This does not indicate the phase is actually missing.
The voltage that triggers an AC Voltage Low fault is 3�0V for a ��0VAC nominal line; 300V for a 3�0, �00 or �15VAC nominal
line; 175V for a 20� or 230 VAC line.
Possible cause:
• Incoming voltage is now, or was previously, too low.
o Power distribution wires or power cord too small for the load.
o Loose or high resistance connection somewhere in the power distribution or power cord connection.
• Bad connection at J62 on the System Bias board or J27 on the CCM.
• Bad connection at J61 jumper on the System Bias board.
• System Bias board defective.
• CCM defective.