Schweitzer Engineering Laboratories SEL-700G Series, Instruction Manual

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4.159
Date Code 20170814 Instruction Manual SEL-700G Relay
Protection and Logic Functions
Group Settings (SET Command)
Figure 4.111 Synchronism-Check Function Angle Characteristics
The TCLOSDX setting predicts the time that it will take for the generator
main breaker to close, from the instant the SEL-700G Relay Word bit
CLOSEX asserts, to the instant the breaker main contacts close. Enter a value
that is as accurate as possible, to obtain the best performance of the 25C close-
initiating Relay Word bit.
If the relay uses the 25C Relay Word bit to initiate a closure, and the breaker
has not closed when the phase angle difference between the generator and
system reaches the CFANGLE setting, the relay asserts the BKRCF breaker
close failure Relay Word bit. This Relay Word bit typically would be used to
close a relay output contact to energize the bus lockout relay. The bus lockout
relay would trip all breakers connected to the bus, protecting the generator
from the out-of-synchronism close.
The synchronism-check function is blocked when the BSYNCHX SEL
OGIC
control equation result equals logical 1. The function is allowed to operate
when the BSYNCHX SEL
OGIC
control equation result equals logical 0.
Typically, the BSYNCHX SEL
OGIC
control equation should be set so that the
function is blocked when the generator main circuit breaker is closed
(NOT 3POX). You can add other supervisory conditions if necessary for your
application.
Collect the following information to calculate the synchronism-check settings.
➤
Prime Mover Manufacturer Synchronization Guidelines
➤
Synchronism-Check VT Connection and Transformer Ratio
➤
Generator VT Connection and Transformer Ratio
➤
Generator Breaker Closing Time
➤
Generator Step-Up Transformer Winding Turns Ratio and
Connection (only necessary if the transformer is connected
between the generator VTs and the synchronism-checked VT)
Recommendations
Set SYNCPX to select the phase voltage input (generator terminals) that is in
phase with the synchronism-checked voltage (VS).
VP Rotation When
Generator Freq. > System Freq.
(slip > 0.0 Hz)
VP Rotation When
Generator Freq. < System Freq.
(slip < 0.0 Hz)
VP
-90° 90°
180°
0°
V
S
CANGLE
25ANGL1
25ANGL2
CF
ANGL
CAUTION
Synchronism-check requirements and
practices vary widely for different
prime mover types. Be sure to consult
your prime mover manufacturer’s
synchronism-check guidelines as you
prepare these settings or severe
equipment damage or loss of
equipment life may result.