3.65
Date Code 20170601
Instruction Manual
SEL-387-0, -5, -6 Relay
Differential, Restricted Earth Fault, Thermal, and Overcurrent Elements
Overcurrent Element
example, to torque control the inverse-time phase overcurrent element for
Winding 1, an equation is needed for the setting 51PTC. A few simple
possibilities might include:
To enable the element with an external contact input
IN104
, set
51PTC = IN104.
To block the element with this same input, set 51PTC = !IN104 (i.e., NOT
IN104).
To enable the element with
IN104
, but only if Breaker 3 is open, set
51PTC = IN104*!IN106 (i.e., IN104 AND NOT IN106, where
IN106
was
previously defined as representing the 52a 3 contact input)
To enable the element continuously (default setting), set 51PTC = 1.
Overcurrent Settings for Example Application
The differential settings for the example transformer application (see
) were defined earlier. Overcurrent settings were chosen to complete
the protection settings package. These settings are listed at the end of this
section of the instruction manual.
Before setting of any overcurrent elements can occur, these must be enabled
by the configuration settings EOC1 through EOC3. EOC1, EOC2, and EOC3
are set to Y.
For the 230 kV primary winding (Winding 1), three elements are set for
overcurrent tripping of 230 kV Breaker 1. The phase definite-time element,
50P11, is set for 20 A secondary, with a five-cycle trip delay time. The phase
and negative-sequence inverse-time elements, 51P1 and 51Q1, are set to pick
up at 4 A and 6 A, respectively, both using the U2 or U.S. Inverse curve, on
Time-Dial 3, with electromechanical reset characteristics. One of the phase
instantaneous elements, 50P13, is set very low at 0.5 A, along with 50P23 and
50P33 on the other two windings. These elements are employed in a
supervisory mode for the Unlatch Trip function, effectively defining when the
breaker has opened by the dropping of phase current below the element
setting. The 50P14 phase instantaneous element has been set at 4 A, and is
used in an internal supervision function (LED targeting).
For the 138 kV secondary winding (Winding 2), tripping is set for the phase
and negative-sequence inverse-time elements, 51P2 and 51Q2. These are set at
lower pickup values of 3.5 and 5.25 A secondary, using the same curves as
Winding 1, but at a higher Time Dial of 3.5. Tripping is done for the 138 kV
Breaker 2. Phase instantaneous elements 50P23 and 50P24 are used for
supervision, as with Winding 1, set at 0.5 A and 3.5 A, respectively.
For the 13.8 kV tertiary, Winding 3, tripping is by the definite-time element,
50P31, set as an instantaneous element at 7 A and zero time delay, and by the
phase inverse time element 51P3. 51P3 is set for 4 A, at Time Dial 1.3 of the
U2 inverse curve, with electromechanical reset. Tripping is for the 13.8 kV
Breaker 3. The 50P33 and 50P34 phase instantaneous elements are used for
supervision, set at 0.5 A and 4 A.
Содержание SEL-387-0
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