General Description - Megger SCITS100 Mode D'emploi

General Description

Counter Section
The SCITS100 Test Set has a built-in counter unit for measuring the time the relay under test takes to trip the contact
or to re-set itself. These count times are shown on a 5 digit l.e.d. display. The two terminals in the counter area are
for connection to the tripping contacts of the relay under test.
The counter function switch has three positions, each labelled for the three modes of operation, 'Normal', 'runback'
and 'Manual'.
In the 'Normal' mode, the counter is started by the selection of the 'Test' position on the 'Set/Test' switch and
terminated either by (i) the opening or closing of contacts in the relay under test, or (ii) by the current flowing in the
output common terminal falling below the minimum threshold. The threshold value is dependent on the current range
selected, being 60 mA for the 10 A range and 600 mA for the 100 A range.
In the 'Runback' mode, the counter is started by the test relay contacts operating and stopped either by the 'Manual'
push button on the control panel or by the remote hand-held push button.
In the 'Manual' mode the counter is both started and stopped by the 'Manual' push button on the control panel or by
the remote hand-held push button; these are interlinked.
The 'Reset' button sets the counter to zero when necessary.
Overload and Thermal Protection
There is a thermo-magnetic resettable cut-out in series with the main output control wiper. This will trip in the event
of a short circuit at the output terminals or any fault occurring in the output control circuit. To re-set, simply press the
green button when the short circuit has been removed.
For thermal protection, a bi-metallic sensor is mounted in the main transformer. This will operate to protect the
transformer if its temperature goes beyond 80 °C, which is possible when the duty cycle is exceeded.
Both the above circuits trip the contactor, controlled by the main 'Set/Test' switch, thus removing the output.
For safety, the SCITS100 has been designed such that when the contacts operate on the relay under test and
terminate the counter, the output is switched off and is not re-energised until the controls are re-set even if the relay
contacts re-set first. This applies also when a power failure occurs with the 'Set/Test' switch in either the 'Set' or 'Test'
positions.
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