GE SecoGear Application Guide

SecoGear Medium-voltage Switchgear Application and Technical Guide DET-882
SecoGear Switchgear Applications
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TRANSFORMER PRIMARY FEEDERS (TPF)
A transformer primary feeder is similar to a general-purpose
feeder, except the entire load is one transformer and the
circuit is typically protected with transformer differential
relays. If transformer differential protection is not required,
use a general-purpose feeder.
Protective Scheme Selection
Basic devices included in a transformer primary feeder are
the same as those included in a general-purpose feeder plus
three additional current transformers for the differential
protection, a transformer fault-pressure auxiliary relay
(63PX) and a GE Series 95 lockout relay (86T).
Differential protection can be in the form of separate relays,
such as GE Type STD single-phase transformer differential
relays (87T), or as part of a complete multifunction
transformer protection package, like GE relays 845, T35, or
T60.
Optional Equipment Selection
Options for a transformer primary feeder are the same as
for a general-purpose feeder, except that automatic
reclosing is not used. Select options for TPF-1, TPF-2, or TPF-
3 on the same basis as for GPF-1, GPF-2, or GPF-3 (see GPF
“Protective Scheme Selection,” above).
Figure 5-2: Transformer Primary Feeder
SINGLE-SOURCE INCOMING LINES (SSIL),
OR DUAL SOURCE WITH NORMALLY OPEN TIE BREAKERS
A single source incoming line is a metal-clad section
containing a power circuit breaker acting as the main
disconnect between a main power distribution bus and the
only source of power supplying the bus.
A system with two or more incoming lines, with supply
distribution buses sectionalized by normally open bus-tie
breakers, requires essentially the same type of protection,
instrumentation, and control for each incoming line as a
single source incoming line.
Protective Scheme Selection
• SSIL-1: Use this type of incoming line for an impedance
or solidly grounded system fed from a local wye-
connected transformer with a current transformer in the
transformer neutral connection.
This type of incoming line would include three-phase
time-over-current protection (51) and a ground-over-

GE SecoGear Specifications

General

Brand	GE
Model	SecoGear
Category	Switch
Language	English