Tweco 400 XT Ultra-Cut Plasma Cutting System With Automated Gas Control - Manual (Page 187)

ULTRA-CUT 400 XT
Manual 0-5306 APPENDIX A-63
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.
2. It is unlikely that an open connection on the J61 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 J61.
3. If the incoming voltage is OK and the problem persists it may be the System Bias board, the CCM or the connection
between J62 and J27.
a. If the incoming voltage is OK and D4 is on or signal “AC V HIGH b” on J62-6 is “high” (about 24VDC, relative to TP1
or J62-8 ) the System Bias board is defective.
b. If D4 is not on and the signal “AC V HIGH b” on J62-6 is “low” (about 10-14VDC, relative to TP1 or J62-8) then System
Bias is OK and problem is in the CCM.
c. If J62-6 is near zero volts there may be bad connection between J62-6 and J27-6 or J62-7 and J27-6.
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, D14, ACV LOW, and sets the
signal “AC V LOW b” on J62-10 to a “high”, about 24VDC (normal for a “low” here is 10-14VDC). 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 380V for a 480VAC nominal line; 300V for a 380, 400 or 415VAC nominal
line; 175V for a 208 or 230 VAC line.