P.3.317
Date Code 20151029 Protection Manual SEL-411L Relay
Protection Functions
Protection Application Examples
Use the data from Table 3.166 to calculate the secondary impedances listed in
Table 3.167.
Application Summary
This application is for two circuit breakers with single-pole tripping and the
following protection functions:
➤ Line current differential protection
➤ Stub bus protection
➤ Stepped distance backup protection
Relay settings that this example does not mention do not apply to this
application example.
Global Settings
Choose appropriate names for the Station and Relay ID.
We would have the following at Terminal S:
SID := Station S Station Identifier (40 characters)
RID := Relay S Relay Identifier (40 characters)
Source R impedance
Z1R = Z0R 20 88° primary
Maximum line load current 1500 A 30° primary
PTR (potential transformer ratio) 500 kV: 111.11 V = 4500 (both stations)
CTR (current transformer ratio) 1600:5 = 320 (relay S)
2000:5 = 400 (relay R)
Nominal relay current 5 A secondary
CT class C800
Total CT burden 1.25
Phase rotation ABC
Ta b l e 3.1 67 Se co nd ar y Va l u es
Parameter Value
Line impedance - Relay S (CT/VT = 0.071)
Z1L
Z0L
B1L
B0L
2.514 87.9°
9.602 76.4°
8.86 mS
4.923 mS
Line impedance - relay R (CT/VT = 0.089)
Z1L
Z0L
B1L
B0L
3.143 87.9°
12.002 76.4°
7.08 mS
3.93 mS
Table 3.166 System Data—500 kV Overhead Transmission Line and CT/PT
Ratios (Sheet 2 of 2)
Parameter Value
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