2.12.4
Directional Overcurrent Relays
Directional overcurrent relays shall be as follows:
a.
Directional phase overcurrent relays shall be single-phase,
instantaneous units. Phase relays, device 67, shall have an
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].
b.
Directional ground overcurrent relays, device 67N, shall have an
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].
2.12.5
Automatic Reclosing Relay
Relay, device 79, shall be of the three-phase, four-reclosure type,
providing immediate initial reclosure, and three time-delay reclosures.
Adjustable time delays shall be 10 to 60 seconds for reset and 0 to 45
seconds for reclosing. Units shall have instantaneous trip lockout after
any preset trip when closing in on a fault. Auxiliary devices shall
provided for lockout when an associated circuit breaker is tripped after
reclosures and automatically reset when an associated circuit breaker is
not tripped after any reclosure.
2.12.6
Transformer Differential and Lockout Relays
Differential relays, device 87T, shall be of the three-phase or the
single-phase high-speed [_____] [percentage] [_____] differential type
suitable for the protection of two-winding transformers, and shall be
provided with a harmonic-restraint feature. Lockout relay, device 86T,
shall be of the type which, when used in conjunction with the 87T relay,
2.12.7
Bus Differential and Lockout Relays
Bus differential relay, device 87B, shall be of the three-phase or
single-phase, high-speed impedance differential type suitable for
protection of buses. Lockout relay, device 86B, shall be of a type which,
when used in conjunction with the 87B relay, trips and locks out the
2.13
INSTRUMENT TRANSFORMERS
2.13.1
General
Instrument transformers shall comply with ANSI C12.11 and IEEE C57.13.
Instrument transformers shall be configured for mounting in/on the device
to which they are applied. Polarity marks on instrument transformers shall
be visually evident and shown on the drawings.
SECTION 16475A
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