ESAB Precision Plasmarc EPP-450 Manuel D'instructions page 59

section 6 troubleshootinG
6.8 arc current detector circuits
There are three Arc Current Detector circuits in the EPP-450. One is used internally to control the Pilot Arc Contactor, K4.
The other two are available for remote use.
A galvanically isolated transistor Current Detector Output is accessible at J1-G (-) and J1-P (+). J1 is the 24 conductor con-
nector on the EPP-450 front panel. The transistor is best suited for switching small relays or low current logic signals like
those utilized by PLC's (Programmable Logic Controllers). The transistor can withstand a maximum peak voltage of 150V.
It can switch a maximum of 50 mA. The transistor turns on whenever the arc current through the Work Lead exceeds 3A.
Pilot arcs not establishing main arcs will not turn on the transistor.
A second current detector output is available at TB8-3 and TB8-4. This output is supplied by an isolated relay contact rated
for 150V, 3 Amperes. This contact is closed when the primary input power to the EPP-450 is off. It opens whenever primary
power is supplied to the power source, and it closes when main arc current is established. Like the transistor output, the
relay contact closes whenever the arc current through the Work Lead exceeds 3A. Pilot arcs not establishing main arcs will
not close the contact.
J6-D J6-E J1-G J1-P
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