GE MLJ1000 Manual page 7

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.
Close enable
Close enable is defined by three conditions in the system:
• The difference in amplitude of the two voltage signals to be synchronized defines a circle shifted
from the axis of abscissa a distance equal to the magnitude of the minimum vector and having a
maximum radius equal to the difference ∆V.
• The angular difference, allowed either in positive or negative, between the two approaching vectors,
forms a cone on which the close enable takes place.
• The frequency slip, ∆f = f
basic condition of closure, optimum for carrying out closure procedures in ideal conditions, with
similarity between signals.
V
1
θ
1
∆ f =
f

GEK - 105560
, which has to be less than that specified, configures a third and
- f
1 2
∆ V
V
2
θ
2
- f

1 2
CLOSE ENABLE
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