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Introduction and Specifications
Date Code 20060731
SEL-300G Instruction Manual
SEL-300G R
ELAY
P
ROTECTION
A
PPLICATIONS
Complete Generator Primary Protection
When ordered with the optional differential elements, the SEL-300G provides a full complement
of primary protection elements for large machines. The relay is built on the field-proven
SEL-300 Series Relay platform, known for secure, dependable, high-performance protection.
DWG: M300G028
SEL-387
Unit Differential
SEL-300G1
Primary
SEL-300G0
Backup
∠
or
Figure 1.1: Large Generator Primary and Backup Protection
In these applications, three- or four-wire potentials and three-phase currents are applied to the
relay for principal protection and metering functions. When differential protection is included,
three additional phase current measurements are required.
Neutral voltage for 100 percent stator ground protection is taken from the secondary of the
grounding transformer. The SEL-300G neutral voltage input is rated for application up to
300 Vac, which means that, for most applications, an auxiliary voltage transformer will not be
necessary between the grounding transformer secondary and this relay.
In applications where neutral overcurrent protection is desired, the SEL-300G neutral current
input, IN, may be connected to the secondary of a neutral current transformer. This transformer
may be located in the generator neutral or connected in the secondary circuit of the grounding
transformer. In solidly grounded or resistance grounded applications, the SEL-300G0 and
SEL-300G2 Relays offer ground differential (87N) protection.
Summary of Contents for SEL-300G
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