Schweitzer Engineering Laboratories SEL-787-2 Manual page 3

Table 2 SEL-787 Protection Elements (Sheet 2 of 2)
Protection Elements
51N Neutral Time-Overcurrent
27P Phase Undervoltage
27PP Phase-to-Phase Undervoltage
27S VS Channel Undervoltage
27I Inverse-Time Undervoltage
59P Phase Overvoltage
59PP Phase-to-Phase Overvoltage
59Q Neg.-Seq. Overvoltage
59G Ground Overvoltage
59S VS Channel Overvoltage
59I Inverse-Time Overvoltage
24 Volts/Hz
25 Synchronism Check
32 Directional Power
49RTD Resistance Temperature Detector
(RTDs)
60LOP Loss of Potential (LOP)
81 Over- and Underfrequency
BF Breaker Failure
a
Refer to Table 3 for the available REF elements.
Table 3 Available Differential and REF Elements
Elements
Differential Protection Windings
(Standard)
REF Elements (Standard)
Differential Protection Windings
(Winding 3 Configured for REF)
REF Elements
(Winding 3 Configured for REF)
➤
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.
Schweitzer Engineering Laboratories, Inc.
SEL-787-2X SEL-787-21
X
X X
X X
SEL-787-2X SEL-787-21
2 2
0 1
SEL-787-2E SEL-787-3E SEL-787-3S SEL-787-4X
X X
X X
X X
X X
X X
X X
X X
X X
X X
X X
X X
X X
X X
X X
X X
SEL-787-2E SEL-787-3E
2 3
1 1
2
2
3
X
X
X
X
X
X
X
X
X
X
X
X
X
X X
X
X
X X
SEL-787-3S SEL-787-4X
3 4
0 0
2 3
2 2
SEL-787-2, -3, -4 Data Sheet