Installation and Operating Instructions - Crompton Instruments

There is a relationship between the phase angle and the slip frequency settings. When one
parameter is adjusted, the setting range of the other may be automatically adjusted to prevent a
condition where the relay may never close.
CAUTION: This trip relay can be configured to Latch. This feature may be
undesirable, if enabled in error.
TYPE 25D — SYNCHRONISING/SYNCHRONISM-CHECK WITH DEAD BUS
This function operates as a permissive relay, where the ‘not tripped’ condition indicates that the
two systems are within the permitted limits to allow synchronism. A ‘tripped’ condition indicates
that the systems are not within the allowable limits, and synchronism is not possible.
The status display will indicate 25D# (relay is tripped) when the relay is not in synchronism. The
display indication will disappear when synchronism is achieved, or when the BUS voltage is
below the ‘Deadbus’ setting.
When failsafe is set to ‘yes’, the relay contacts will energize when the GEN and BUS circuits are
in synchronism. An out-of-sync condition, or loss of auxiliary supply, will de-energize the relay
contacts.
Brief details
The relay either:
(a) operates when the “Bus” and “Generator” signals are within the selected limits of
frequency, phase angle, voltage and the phase sequence of the “Generator” voltage
inputs is correct for the duration of the selected delay
or:
(b) the voltage on the “Bus” voltage input is below the selected limit and the phase
sequence of the “Generator” voltage inputs is correct for the duration of the selected
delay to permit or to cause the paralleling of two circuits. The relay will return to the
“tripped” condition when any one of the conditions detailed above become invalid. The
time delay is used on the transition to the “not tripped” condition.
Parameters
You must specify the following parameters for operation of the synchronising relay:
●
The maximum permitted phase angle between the “Bus” input voltage and the
reference “Generator” voltage (V1, VA, or V1-2),
●
The maximum permitted voltage difference between the “Bus” input voltage and the
reference “generator” voltage,
●
The maximum permitted frequency difference between the “Bus” and “Generator”
(slip frequency)
●
The maximum voltage that may be present on the “Bus” voltage input before the phase,
frequency and voltage difference conditions are required to qualify the trip condition (for
levels below this voltage the relay will operate providing that the phase sequence of the
“Generator” voltage inputs is correct).
●
The time for which these conditions must be true
• The minimum voltage level, below which they function.
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