25 – 6
Also using a single source, the system can be tested to verify that the circuit breaker will not trip.
Figure 6
Circuit Breakers using Direct Sensing Ground Fault Protection via the External GF Sensor (iron core)
The WL trip units can be connected to an external 1200:1 iron core sensor to provide indication of a ground fault. This configuration
requires that the Ground Fault Mode switch be in the down (g) position. The ETU is activated by injecting 80-100A through the breaker itself
(Source A). Once the ETU is active, the test current can be injected through the external ground fault sensor to verify its connection and
polarity (Source B). The external ground fault sensor does not provide energy to the ETU to activate it.
Figure 7
The same test can be conducted using a single power source. The ETU must be activated by injecting a minimum of 100A through the
breaker itself. The external neutral sensor does not provide energy to the ETU to activate it. Multiple windings through the external sensor
can be added to simulate greater neutral currents.
Figure 8
ETU
Source
External Air-Core GF Sensor
on Neutral or Ground Bus
Secondary Terminals
X8-9 & X8-10
ETU
Source A
Source B
Secondary Terminals
X8-11 & X8-12
External Iron Core Sensor on
Neutral or Ground Bus
ETU
Source
External Iron Core GF Sensor
on Neutral or Ground Bus
Secondary Terminals
X8-11 & X8-12
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