Schweitzer Engineering Laboratories SEL-787-2 - Page 3

Schweitzer Engineering Laboratories, Inc. SEL-787-2, -3, -4 Data Sheet
3
➤
Standard Protection Features. Use standard dual-slope differential protection with harmonic blocking and restraint
for as many as four windings and as many as three independent REF elements for sensitive ground-fault detection in
grounded wye-transformers. Refer to Table 3 for the available REF elements. The relay also includes phase,
negative-sequence, residual ground, and neutral-ground overcurrent elements for backup protection. Breaker failure
protection for as many as four three-pole breakers is standard.
➤ Additional Protection Features. Take advantage of the SEL-787-3E/3S/2E models volts/hertz protection with
frequency tracking from 15 to 70 Hz for generator step-up and variable frequency applications. Use over- and
underfrequency and over- and undervoltage elements to implement load shedding and other control schemes on the
relay.
51N Neutral Time-Overcurrent X X X
27P Phase Undervoltage X X X
27PP Phase-to-Phase Undervoltage X X X
27S VS Channel Undervoltage X
27I Inverse-Time Undervoltage X X X
59P Phase Overvoltage X X X
59PP Phase-to-Phase Overvoltage X X X
59Q Neg.-Seq. Overvoltage X X X
59G Ground Overvoltage X X X
59S VS Channel Overvoltage X
59I Inverse-Time Overvoltage X X X
24Volts/Hz XXX
25 Synchronism Check X
32 Directional Power X X X
49RTD Resistance Temperature Detector
(RTDs)
X X X X X X
60LOP Loss of Potential (LOP) X X X
81 Over- and Underfrequency X X X
BFBreaker Failure XXXXXX
a
Refer to Table 3 for the available REF elements.
Table 3 Available Differential and REF Elements
Elements SEL-787-2X SEL-787-21 SEL-787-2E SEL-787-3E SEL-787-3S SEL-787-4X
Differential Protection Windings
(Standard)
222334
REF Elements (Standard) 0 1 1 1 0 0
Differential Protection Windings
(Winding 3 Configured for REF)
223
REF Elements
(Winding 3 Configured for REF)
222
Table 2 SEL-787 Protection Elements (Sheet 2 of 2)
Protection Elements
2 Windings
2 Windings With
IN Channel
2 Windings With
IN Channel and
3-Phase Voltages
3 Windings With
IN Channel and
3-Phase Voltages
3 Windings With
VS/VBAT Channel and
3-Phase Voltages
4 Windings
SEL-787-2X SEL-787-21 SEL-787-2E SEL-787-3E SEL-787-3S
SEL-787-4X