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2.3.1
Connections
Ensure that the outputs are switched off and that the device under test is isolated before
making any connections.
Connect the main outputs as shown in figure 2.3, selecting the most appropriate ammeter
range for the device under test.
Set the phase select switch to trigger the timer on the desired phase.
2.3.2
Test procedure
Set the output controls to zero (anti-
clockwise) and the timer mode to “OFF”.
Switch on the main output, and increase the outputs to the desired level.
Switch off the main output.
Switch the timer to “CURRENT OPERATED” mode, and reset the breaker if it has tripped.
Switch the main output on. The timer will start when current starts flowing in the device under
test, and will stop when the device trips.
2.3.3
Devices with short trip times
When testing devices with short trip times (such as thermal circuit breakers at high over-
current factors), setting the current may cause the breaker to trip. In such circumstances, set
the current using pulse mode. In this mode, current will be injected for 500ms and the current
logged
every time the “ON” button is pressed.
