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2.3.1
Timer Modes
2.3.1.1 Timer Mode: Off
In the ‘off’ mode, the timer has no effect on the operation of the set, and the timer does not
run. This mode is used to set the required current through the test object before a timing test.
2.3.1.2 Timer Mode: Internal Start
The internal start mode starts the timer when the main output is switched on, and stops the
timer on the first change of contact set 1. When the timer is stopped, the output of the unit is
automatically switched off.
2.3.1.3 Timer Mode: Single Contact
In single contact mode, the timer starts on the first change of state of contact set 1 after the
output is switched on, and stops on the second change on contact set 1. The output is
automatically switched off when the timer is started. The timer is reset when the output is
switched on. This timer mode is ideally suited to timing auto-reclose relays.
If a single contact mode is required where the output remains on until the second change of
contact, this may be achieved by using single contact mode with contact set 2.
2.3.1.4 Timer Mode: Dual Contact
Dual contact mode uses both contact set 1 and contact set 2. The time between C1 and C2
changing is always measured whether C1 or C2 changes first. If C1 changes first, the output
switches off when the timer stops. If C2 changes first, the output switches off when the timer
starts. In dual contact mode the timer will initially start when the output is switched on, but will
restart on the first contact change.
2.3.1.5 Timer Mode: Current Operated
Current operated mode is used to time devices that have contacts in series with the current
sense element. This includes miniature circuit breakers and MCBs.
The timer is started when the output current exceeds 20% of full scale of the selected
metering range, and stops when the current falls below this threshold.
