Closing time delay

The minimum closing time, set at 100 ms, is actually 160 ms, as it is necessary to add the time required by

the measurement units and the operation of the output relays to the set 100 ms. It should be kept in

mind that during the first cycles, from the time of a closure, the voltage is stabilizing both in the line as

well as in the buses and it is no desirable to allow a closure under these conditions. What is more, it is

necessary to take into consideration the response of both the high voltage transformers and the internal

transformers of the relay.

There is also a time for sustaining the permission signal, which always has a fixed value of some 130 ms.,

being the result of a prefixed delay of 100 ms. added to the dropout time of the measurement units (one

cycle = 20 ms. at 50 Hz.) and the deactivation of the output relay (10 ms.).

Minimum settings

Barring any special requirements, it is not recommended to use settings that near the minimum limits for

the relays, (2 V for the voltage difference, 2º for the angle difference), so as to avoid being too restrictive

in close enabling, given the real characteristics of accuracy in the installations, measurement transformers,

etc.