Schweitzer Engineering Laboratories SEL-151C User manual

Date Code 910703 SEL-151C Addendum A-1
SEL-151 Instruction Manual
SEL-151C INSTRUCTION MANUAL ADDENDUM
This addendum explains SEL-151C relay operations that differ from those described in the
SEL-151 Instruction Manual. The major differences are that the SEL-151C relay has no
reclosing relay or fault locator, but adds phase mho distance elements for more selective torque
control.
Consider using the SEL-151C relay in bus applications where the mho elements can discriminate
between remote faults and the combined loads of several feeders.
Differences between the SEL-151 and SEL-151C Relay Words are underlined below.
SEL-151
R1 51P 50L 50H 51QP 50Q 51NP 50NL 50NH
R2 51T 50LT 50C 51QT 50QT 51NT 50NLT 27
R3 79RS 79CY 79LO 79SH 52AT 52BT IN6 IN5
R4 PDEM QDEM NDEM TF CF TCMA ST
R5 A B C D E F G H
R6 J KT !L V W X Y ZT
SEL-151C
R1 51P 50L 50M 51QP 50Q 51NP 50NL 50NH
R2 51T 50LT 50MT 51QT 50QT 51NT 50NLT 50H
R3 21P 50C 27 52AT 52BT IN6 IN5
R4 PDEM QDEM NDEM TF CF TCMA ST
R5 A B C D E F G H
R6 J KT !L V W X Y ZT
Note: 50H, 50C, and 27 are in different locations in each Relay Word.
79RS, 79CY, 79LO, and 79SH are not in the SEL-151C Relay Word because the
SEL-151C relay does not include a reclosing relay.
The SEL-151C relay has an extra definite-time phase overcurrent element (50MT) with
pickup (50M). These elements have the same setting range and tolerance as 50LT and
50L, respectively.
The SEL-151C relay has a single-zone self-polarized mho distance element (21P).
FUNCTIONS AND SETTINGS NOT INCLUDED IN THE SEL-151C RELAY
The SEL-151C relay has no reclosing relay. Thus, it does not have the following SEL-151 relay
settings:
79OI1, 79OI2, 79OI3, 79OI4, 79RST, M79SH, RC, SEQ, RE as an input option
The SEL-151C relay can perform circuit breaker closing via the CLOSE command or a DC
(Direct Close) input. The Close Failure function is operable in the SEL-151C relay (setting CFT,
Relay Word bit CF).

A-2 SEL-151C Addendum Date Code 910703
SEL-151 Instruction Manual
There is no fault locator in the SEL-151C relay. Thus, the SEL-151C relay does not have the
following SEL-151 relay settings:
R1, X1, R0, X0, RS, XS, LL (line impedance and length parameters)
EXTRA ELEMENTS AND SETTINGS IN THE SEL-151C RELAY
The SEL-151C relay has an extra definite-time phase overcurrent element (50MT) with pickup
(50M).
50M - pickup for 50MT (amps, secondary) 0.50 to 100.00 amps
50MT - time delay for 50MT element (cycles) 0 to 16000 cycles
The column space allotted for "79" in the SEL-151 relay event report shows the phase
overcurrent elements in the SEL-151C relay. The new column is labeled "50M" and appears with
the other "P" columns as shown below.
12/*0VU*O

5%#5"
$&,-
-.*)-).3$3
Event
Report Column
Elements
Asserted
Symbol
Displayed
50M 50M 50MT
0 0 .
0 1 (not possible)
1 0 p
1 1 t
The 50H element cannot be torque controlled in the SEL-151C relay, so the "50H" column
appears to the right of the "TCI" (torque control, internal) column in the event report. The 50M
and 50MT elements can be torque controlled.
The SEL-151C relay has three single-zone self-polarized mho distance elements (21AB, 21BC,
and 21CA). The following SEL-151C relay settings cover the distance elements.
ZP - Reach (ohms, secondary) 1 to 64 ohms
MTA - Maximum Torque Angle (degrees) 0 to 90 degrees
21PC - 21P = 21AB + 21BC + 21CA (21PC = 2) or
21P = 21AB * 21BC * 21CA (21PC = 3)
For more information, see Figure 2.20 in the SEL-151 Instruction Manual.
21P is also an optional internal torque control element for the phase overcurrent elements (via the
TCI setting for the SEL-151C relay). 50C and 27 are optional internal torque control elements
for the phase overcurrent elements in both relays.

Date Code 910703 SEL-151C Addendum A-3
SEL-151 Instruction Manual
Element Choices
for TCI
Setting
TCI =
21P 50C 27
0 0 0 0 Rows 1–4 are settings
0 0 1 V for both relays
0 1 0 I
0 1 1 3
1 0 0 Z Rows 5–8 are additional settings
1 0 1 5 for the SEL-151C relay only
1 1 0 6
1 1 1 7
To fully utilize the relay's resources, self tests are delayed when any of the following elements are
picked up:
51P, 50H, 51QP, 50Q, 51NP, 50NL, 50NH
51T, 51QT, 50QT, 51NT, 50NLT, and 21P.
Therefore, you should be careful to set the relay so that under normal conditions none of these
elements are picked up.
In the event reports of both relays, the TCI column displays these symbols. This column allows
you to monitor internal torque controlling elements in the event report.
Event
Report
Column Elements Asserted
Symbol
Displayed
TCI 21P 50C 27
0 0 0 0 Rows 1–4 are symbols
0 0 1 V for both relays
0 1 0 I
0 1 1 3
1 0 0 Z Rows 5–8 are additional symbols
1 0 1 5 for the SEL-151C relay only
1 1 0 6
1 1 1 7
FRONT PANEL TARGET LED DIFFERENCES
The two right most target LEDs indicate enable (EN) and alarm (ALRM) in the SEL-151C relay.

A-4 SEL-151C Addendum Date Code 910703
SEL-151 Instruction Manual
FIRMWARE IDENTIFICATION DIFFERENCES
See Firmware Identification in Section 4: EVENT REPORTING in the SEL-151 Instruction
Manual for comparison.
For the SEL-151C relay family, version specifications are interpreted as follows:
V[VS] = V[ABCDEFG]
Option Specifier Specifier Meaning Option Description
A 5, 6 50 Hz, 60 Hz Power System Frequency
B 1, 5 1 amp, 5 amps Nominal Amps per Phase
C 6 120 & 67 volts Nominal Volts per Phase
D n none Fault Locator type
E p, n positive, negative Phase-Sequence of Power System
F 0 none Recloser
G e enable and alarm Target LEDs
Figure 1: SEL-151C Relay Typical AC Current and Voltage Connections

Date Code 910703 SEL-151C Addendum A-5
SEL-151 Instruction Manual
Figure 2: SEL-151C Distribution Bus Relay Horizontal Front and Rear Panel Drawings