2.7.5
SUBSTATION AND SWITCHGEAR PROTECTIVE 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.
**************************************************************************
2.7.5.1
General
[Solid-state] [and] [Electromechanical] [and] [Microprocessor-based]
protective relays shall be provided as shown and shall be of a type
specifically designed for use on power switchgear or associated electric
power apparatus. Protective relays shall conform to IEEE C37.90. Relays
and auxiliaries shall be suitable for operation with the instrument
transformer ratios and connections provided.
2.7.5.2
Construction
Relays shall be of the semi-flush, rectangular, back-connected, dustproof,
switchboard type. Cases shall have a black finish and window-type
removable covers capable of being sealed against tampering. Relays shall
be of a type that can be withdrawn, through approved sliding contacts, from
fronts of panels or doors without opening current transformer secondary
circuits, disturbing external circuits, or requiring disconnection of any
relay leads. Necessary test devices shall be incorporated within each
relay and shall provide a means for testing either from an external source
of electric power or from associated instrument transformers. Each relay
shall be provided with an operation indicator and an external target reset
device. Relays shall have necessary auxiliaries for proper operation.
Relays and auxiliaries shall be suitable for operation with the instrument
transformer ratios and connections provided.
2.7.5.3
Ratings
Relays shall be the manufacturer's standard items of equipment 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.
2.7.5.4
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-phase, 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]
SECTION 16311A
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