GE SecoGear Application Guide

DET-882 SecoGear Medium-voltage Switchgear Application and Technical Guide
System and Equipment Protection
©2017 General Electric All Rights Reserved 33
Table 4-1: Remote Control Schemes
Control Location
Local
Remote
Devices Required
(in addition to remote control switch)
Breaker Operation
Close
Trip
Close
Trip
Breaker Position
Conn
Test
Conn
Test
Conn
Test
Conn
Test
Remote
Control
Scheme
A
X X X X X X
Local permissive switch (69CS), plus breaker
position switch (52POS)
B X X X X
Local permissive switch (52CS), plus breaker
position switch (52POS)
C* X X X X X
Local permissive switch (52CS), plus breaker
position switch (52POS)
Basic Control
X
X
X
X
Control switch (52CS)
Key:
X = This manually initiated operation is possible.
* = This scheme uses same devices as scheme B, but different wiring.
Instrumentation, Current, and Voltage Transformers
Basic current or voltage indication in SecoGear switchgear
can be via a switchboard type analog meter and transfer
switch, a digital meter, or can be a feature of a
multifunction protective relay. Most solid-state
multifunction relays today offer some type of metering
capabilities, including voltage, current, watts, vars,
frequency, and the demand functions.
AM and VM Scales
Ammeter scales are determined by the CT ratio. Current
transformer ratings are normally selected based on
approximately 125 % of the ampacity of the feeder circuit
conductors. Current transformer ratios selected in this
manner permit settings of circuit overcurrent-protective
relays to provide good selectivity and protection. For a
properly designed circuit, operating at full load, this means
a maximum scale reading of between half and three-
quarter scale.
For a circuit that provides for substantial future expansion,
lower scale readings will indicate initial-load conditions.
The voltmeter scale, determined by the voltage
transformer ratio, is 125 percent of the nominal line-to-line
VT rating. Optional wattmeters and varmeters, switchboard
type, are available for most equipment. Wattmeter and
varmeter scales are determined by the CT and VT ratios.
CT and VT Ratios
Standard window-type current transformers are available
in ratios ranging from 50:5 to 4000:5 amperes. The basic
ground-sensor window-type CT (GSCT) ratio is 50:5
amperes, with a 7.25 in window. Relay accuracy class is
per IEEE C37.20.2-2015, Table 4. Higher accuracy classes
may be available; however, space for mounting such CTs is
limited.
Table 4-2: Single Ratio CTs
CT Ratio
Standard
Accuracy Class
High Accuracy
Class
1
50:5 A
C10
100:5 A
C10
C20
150:5 A
C20
C50
200:5 A
C20
C50
250:5 A
C20
C50
300:5 A
C20
C100
400:5 A
C50
C100
500:5 A
C50
C100
600:5 A
C100
C200
800:5 A
C100
C200
1000:5 A
C100
C200
1200:5 A
C200
C400
1500:5 A
C200
C400
2000:5 A
C200
C400
2500:5 A
C200
C400
3000:5 A
C200
C400
4000:5 A
C200
C400
5000:5 A
C200
C400
Note:
1. High accuracy requires twice the mounting space of a standard
accuracy CT.

GE SecoGear Specifications

General

Brand	GE
Model	SecoGear
Category	Switch
Language	English