Tweco Troubleshooting Power Supply - Manual (Page 26)

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Cut Demand from CCM may be measured at TP13 on CCM I/O PCB (TP1
common) or J35-2. Before CNC START, Cut Demand is set to zero, if it is other
than zero CCM is defective.
After receiving CNC START and during preflow Cut demand is set to a lower
starting level (varies with output current setting and MAX current capacity of the
unit) generally between 0.5 to 3.5 volts. Upon arc transfer Cut Demand ramps up
to cutting level with a MAX of 10 VDC if current is set to MAX output.
It is likely if a CCM fault causing code 2-6 occurs it will be in hardware that
makes the demand a constant level, over 10V. However if the demand is normal
during pilot, then ramps too high, OCR will likely occur to quickly to see with a
meter, will require an oscilloscope.
Cut Demand PCB5 WK-5602
Do not make measurements on WK-5602 board with HF firing. Noise may be
introduced than can cause catastrophic inverter failure. Instead use following
method:
To measure demand signals without introducing HF noise disconnect the RAS
(Remote Arc Starter) control cable at the RAS end, J58, so the pilot doesn’t start.
At the end of preflow CCM will attempt to ignite pilot for 15 sec. (Because
pilot won’t ignite, status code 1-2 will flash on power supply front panel). The
CCM will apply the Pilot Demand and Cut Demand for preflow time (default 2
sec but can be increased up to 8 sec if more time is needed) plus 15 sec. ignition
time giving enough time to measure with voltmeter.
Some of these values are preliminary and may change a little with later CCM
revisions.
Initial Cut Demand -- Chopper Pilot Systems
Cut Current
100A
SYS
150A
SYS
200A
SYS
300A
SYS
0-10 1.5 1.0 0.8 0.5
11-25 1.7 1.1 0.8 0.6
26-35 2.0 1.3 1.0 0.6
36-55 2.4 1.6 1.2 0.8
56-75 2..5 1.6 1.2 0.8
76-105 2.6 1.7 1.3 0.9
106-135 - 1.8 1.4 0.9
136-155 - 2.0 1.5 1.0
156-210 -
- 1.5 1.0
211-300 - - - 1.0
Some early power supplies have pilot resistor(s) instead of chopper regulators.
NEED CHART
For those units Initial Cut Demand will be slightly higher.
Cut Demand leaves CCM I/O PCB from J35-2 (26 ckt ribbon cable) and goes
to CN10 (other end of ribbon cable) on PCB5, WK-5602A. Cut demand is
filtered, scaled to 80% of input (100, 200, & 300A) or 60% (150A) and renamed