ratios and connections provided.
2.12.2
Ratings
Relays shall be the manufacturer's standard items of equipments with
appropriate ranges for time dial, tap, and other settings. Relay device
numbers shall correspond to the function names and descriptions of IEEE
C37.2.
2.12.3
Overcurrent Relays
**************************************************************************
NOTE: Ranges selected will be based on the
coordination study. Refer to TM 5-811-1 and TM
5-811-14 for guidance regarding protective relays.
**************************************************************************
Overcurrent relays shall be as follows:
a.
Phase overcurrent relays for main [and tie] circuit breakers shall
be single-phases, nondirectional, [induction] [solid-state]
[microprocessor-based] type, time delay, device 51, current taps
[[_____] to [_____] amperes] [as indicated] with characteristic
curves that are [definite time] [moderately inverse] [inverse]
[very inverse] [extremely inverse] [as indicated].
b.
Ground overcurrent relays for main circuit breakers shall be
nondirectional, [induction] [solid-state] [microprocessor-based]
type, time delay, device [51G wired to a current transformer in
the source transformer neutral-to-ground connection] [51N,
residually connected], with current taps [[_____] to [_____]
amperes] [as indicted] and with characteristic curves that are
[definite time] [moderately inverse] [inverse] [very inverse]
[extremely inverse] [as indicated].
c.
Ground overcurrent relays for tie circuit breakers shall be
nondirectional, [induction] [solid-state] [microprocessor-based]
type, time delay, device 51N, residually connected, with current
taps [[_____] to [_____] amperes] [as indicated] and with
characteristic curves that are [definite time] [moderately
inverse] [inverse] [very inverse] [extremely inverse] [as
indicated].
d.
Phase overcurrent relays for feeder circuit breakers shall be
single-phase, nondirectional, [induction] [solid-state]
[microprocessor-based] type, device 50/51, with
instantaneous-current pick-up range [[_____] to [_____] amperes]
[as indicated], with time-delay-current taps [[_____] to [_____]
amperes] [as indicated] and with characteristic curves that are
[definite time] [moderately inverse] [inverse] [very inverse]
[extremely inverse] [as indicated].
e.
Ground overcurrent relays for feeder circuit breakers shall be
nondirectional, [plunger] [solid-state] [microprocessor-based]
type instantaneous, device [50GS wires to a ground sensor current
transformer] [50N, residually connected], with current pick-up
range [[_____] to [_____] amperes] [as indicated].
SECTION 16475A
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