GE SecoGear Application Guide

SecoGear Medium-voltage Switchgear Application and Technical Guide DET-882
System and Equipment Protection
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Table 4-3: Multiple Ratio CTs
CT Ratio
Standard
Accuracy
Class
High
Accuracy
Class
600:5 A
50/100/150/200/250
300/400/450/500/600
C100 C200
1200:5 A
100/200/300/400/500
600/800/900/1000/1200
C200 C400
2000:5 A
300/400/500/800/1100
1200/1500/1600/2000
C200 C400
2000:5 A
300/400/500/800/1100/
1200/1500/1600/2000
C200 C400
3000:5 A
300/500/800/1000/1100/
1500/2000/2200/2500/3000
C200 C400
4000:5 A
500/1000/1500/2000/2500
3000/3500/4000
C200 C400
Metering and Test Block
Current transformer relaying accuracy and excitation
characteristics are particularly important when considering
lower-rated current transformers on systems with high
available short-circuit currents and for all differential relay
applications. Excitation characteristics and accuracy
classes are available upon request.
Standard voltage transformers are mounted in rollout
trays, with primary and secondary fusing. Models are
available rated for line-to-line, or line-to-neutral
applications with system voltages from 2400 V to 14400 V.
Control and Transfer Switches
GE Series 95 control and transfer switches are furnished, or
as specified. Test blocks and plugs can be furnished to
facilitate circuit testing, using portable instruments and
meters. The current test block is arranged so that the
current circuit is maintained when the plug is removed
from the block.
Surge Protection
Every medium-voltage AC power system is subject to
transient voltages in excess of normal operating voltages.
There are many sources of transient voltages. The most
prominent ones are
• Lightning
• Physical contact with a higher voltage system
• Resonant effects in series inductive-capacitive circuits
• Repetitive restrikes (intermittent grounds)
• Switching surges
To mitigate the effects of these transient voltages, both
surge arresters and, where appropriate, surge capacitors
should be used. Surge arresters limit the crest voltage of a
voltage surge.
Surge capacitors reduce the steepness of the voltage wave
which reaches the protected equipment. Surge capacitors,
to be most effective, should be located as close to the
protected equipment (usually motors) as possible with
minimum inductance connections
ANSI DEVICE FUNCTIONS AND ACRONYMS
Table 4-4: ANSI Device Codes
Device
Function
1
Master element
2
Time delay starting or closing relay
3
Checking or interlocking relay
4
Master contactor
5
Stopping
6
Starting CIRCUIT BREAKER
7
Rate of CHANGE RELAY
8
Control power disconnecting device
9
Reversing device
10
Unit sequence switch
11
Multifunction device
12
Overspeed device
13
Synchronous-speed device
14
Underspeed device
15
Speed or frequency, matching device
16
Data communications device
17
Shunting or discharge switch
18
Accelerating or decelerating device
19
Starting to running transition contractor
20
Electrically operated valve
21
Distance relay
22
Equalizer circuit breaker
23
Temperature control device
24
Volts per Hertz relay
25
Synchronizing or synchronize-check device
26
Apparatus thermal device
27
Undervoltage relay

GE SecoGear Specifications

General

Brand	GE
Model	SecoGear
Category	Switch
Language	English