Tweco 400 Ultra-Cut XT Plasma Cutting System - Manual (Page 220)

ULTRA-CUT 100 XT/200 XT/300 XT/400 XT
A-86 APPENDIX Manual 0-5297
From the bypass valve in most systems coolant is plumbed to the rear panel coolant supply fitting where it
goes to the torch via the RAS 1000 XT, the remote arc starter, The UC 400 XT had an additional external heat
exchanger, the HE 400XT in the supply line between the power supply and the remote arc starter. In the AC
200 XT with built in arc starter coolant goes to the water cooled HF (high frequency) coil and then to the torch
supply lead attached to the internal torch connection bulkhead. Coolant from the Torch returns to the RAS and
on to the return fitting on the rear of the power supply. For the AC 200 XT return is to the torch bulkhead built
in to the unit. Coolant returning from the torch is routed through the rear panel filter then through the radia-
tor (internal heat exchanger) and through the flow switch. Ultra-Cut models also have a flow sensor in series
the flow switch that can detect bubbles in the coolant. Upon leaving the radiator, coolant goes into the bottom
inverter “cold plate” or liquid cooled heat sink. It flows through the inverters in series and returns to the tank.
detect bubbles in the coolant. Upon leaving the radiator, coolant goes into the bottom inverter “cold plate” or
liquid cooled heat sink. It flows through the inverters in series and returns to the tank.
401 Coolant Level Low
The coolant reservoir (tank) has a normally open (tank dry) float type level switch, LS1. When the coolant level
in the tank is below about ½ full this fault will signal the need to add coolant. It will not stop the process dur-
ing a cut but will instead show the 405 fault as a warning. As soon as the cut stops it will not allow another to
start until the issue is corrected.
Possible causes:
• Coolant is low
• Level switch defective, disconnected or installed upside down.
• Relay board defective or J7 disconnected.
• CCM defective.
Troubleshooting:
1. Confirm visually that the level switch float is below the coolant, if not add more coolant to the tank.
2. Check J7 on the Relay board.
a. If properly connected remove J7 and check continuity between pins 2 and 4 (pins 2 & 3 of J71 on the
switch itself).
b. If no continuity at J71 on the switch, if it is still open, replace the switch.
3. If there was continuity at J7 plug it back in and measure voltage on pin 9 of the 40 pin ribbon cable (Relay
board J4 to CCM J23). Common is TP1 on either the Relay or the I/O board.
a. Pin 9 should be high, about +10 to +15V. If it’s not the relay board is bad or the ribbon cable is shorted.
b. To test the ribbon cable remove both ends, J4 on the Relay board and J23 on the I/O board and measure
from pin 9 of the ribbon cable to both pin 8 and pin 10 of the cable. Both should be open. If not replace
the ribbon cable. Otherwise it’s the Relay board.
4. If pin 9 of the 40 pin ribbon cable was high in step 3.a the CCM is defective.
402 Low coolant Flow
The flow switch FS1 is positioned in series with the radiator where it measures the flow returning from the
torch. The flow switch serves two purposes, one to insure there is adequate flow for cooling needs and two,
it insures the torch consumables are in place so the negative output of the power supply is not exposed. This
function is called “Parts in Place” or PIP. The output cannot be enabled if parts are not in place. The normally
open flow switch requires 0.7 GPM (2.65 liter/min.) +/- about 10% to close.
When the system is turned on and enabled and fails to achieve proper coolant flow after 4 minutes code 404
will be set. Getting code 402 means it initially had enough flow but something has caused the flow to be re-
duced. Listed here are things that might happen during cutting to cause reduced flow. For other causes like
component failures refer to code 404.