The direction of 67N3/Z3GT may be reversed to assist in blocking schemes, weak-infeed
schemes, and local bus protection for looped or double-feed circuits. Directionality may also
be disabled for all three residual overcurrent elements.
The curve shape of the time-overcurrent element is user-selectable. This element is either
non-directional or forward-reaching, as enabled.
Overload Alarm or Protection
The relay demand ammeter feature has a programmable time constant and a settable threshold.
When demand (maximum of the three phases) reaches the setpoint, a bit (DCTH) in the Relay
Word is set. By programming a mask, this bit may be routed to one of the programmable
outputs for an alarm to initiate tripping, or perform any other desired function. Since the
demand interval (time constant) is settable, it may be programmed to match the time constant
of a protected piece of apparatus, e.g., transformer, reactor or line.
Reclosing
A three-shot reclosing relay is provided. Reclosing may be initiated or cancelled for any
conditions recorded in the Relay Word and is accomplished by programming the Reclose
Initiate and Reclose Cancel masks.
GENERAL INFORMATION
Communications functions provide remote and local examination of a wide range of data,
including the voltages and currents presented to the instrument, relay settings, and a history of
the twelve most recent events. Relay settings may be entered and modified remotely. The
relay also allows circuit breaker control via the communications channels. A secure two-level
password access scheme protects settings and circuit breaker control. The ALARM contact
output monitors the relay and may be used to alert personnel of an unauthorized access
attempt.
The SEL-267D relay includes a fault locator which uses fault type, prefault, and fault condi-
tions to provide an accurate estimate of fault location without the need for communications
channels, or special instrument transformers, even during conditions of substantial load flow
and fault resistance. Using a setting you can enable fault locating algorithms best suited for
radial or looped systems.
Date Code 940512
Introduction
SEL-267D/167D Instruction Manual
1-3
Содержание SEL-167D
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