Troubleshooting; Process Troubleshooting - ESAB B Series Installation, Operation And Maintenance Manual

SECTION 7

7.1 TROUBLESHOOTING

WARNING
!
ELECTRIC SHOCK CAN KILL! Be sure that all primary
power to the machine has been externally discon-
nected. Open the line (wall) disconnect switch or
circuit breaker before attempting inspection or work
inside the power source.
WARNING
!
Capacitors can store high voltages even when power
is disconnected or unit is deenergized. Ensure
power supply capacitors are grounded prior to per-
forming maintenance.

7.2 PROCESS TROUBLESHOOTING

A. Programmable Logic Controller (PLC).
The PLC is located in the Precision Plasma Power
Source. It is a device capable of providing pre-
defined outputs depending on state of the inputs.
The precise conditions are programmed and per-
manently stored in the PLC. The PLC is visible
through the plexiglass window on the left side panel
of the power source.
The PLC will provide predefined outputs in re-
sponse to input signals from external devices. This
exchange of signals can be confirmed by observing
the LEDs on the top of the PLC while troubleshoot-
ing. These indications are useful in isolating a
system failure to the most likely device.
The LEDs are divided into two groups; Input (0-15)
and Output (0-11). Input LEDs light when the
corresponding signal is detected by the PLC. Out-
put LEDs light when the PLC issues a signal to an
external device.
LEDs are highly reliable indicators. It is not likely
that one will "burn out". However, if the technician
is not confident that the LEDs are working, the
presence of a signal can be confirmed by using a
meter and taking a measurement on the appropri-
ate pin. Refer to the schematic and wiring dia-
grams.
The signal exchange between the PLC and external
devices are both time and condition dependent. If
a required signal is not received in the proper
sequence, the PLC will discontinue the process and
generate a fault signal to the CNC.
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TROUBLESHOOTING