Schweitzer Engineering Laboratories SEL-749M, Instruction Manual, Page: 69 / 314

4.3
Date Code 20080918 Instruction Manual SEL-749M Relay
Protection and Logic Functions
Main Settings (SET Command)
Main Settings (SET Command)
Identifier Settings
All models of the SEL-749M have the identifier settings described in
Table 4.1 .
The SEL-749M prints the Relay and Terminal Identifier strings at the top of
responses to serial port commands to identify messages from individual
relays.
Enter up to 16 characters, including capital letters A–Z, numbers 0–9, periods
(.), dashes (-), and spaces. Suggested identifiers include the location, process,
circuit, size, or equipment number of the protected motor.
Current Transformer
(CT) Configuration,
Full Load Current
Settings
The CT ratio and full load current settings configure the relay to accurately
scale measured values and report the primary quantities. Calculate the phase
and neutral CT ratios by dividing the primary rating by the secondary rating.
EXAMPLE 4.1 Phase CT Ratio Setting Calculation
Consider an application where the phase CT rating is 100:5 A.
Set CTR1 or CTR2 := 100/5 := 20
See
Equation 4.3
for sample calculations of Motor FLA.
Voltage Transformer
(VT) Configuration
Settings
Table 4.4 shows voltage settings for relay models with optional voltage inputs.
These settings configure the optional relay voltage inputs to correctly measure
and scale the voltage signals. Set the phase PT ratio (PTR) setting equal to the
VT ratio.
Table 4.1 Identifier Settings
Setting Prompt Setting Range Setting Name := Factory Default
UNIT ID LINE 1 16 Characters RID := SEL-749M
UNIT ID LINE 2 16 Characters TID := MOTOR RELAY
Table 4.2 CT Configuration and Full Load Current Settings
Setting Prompt Setting Range Setting Name := Factory Default
PHASE CT RATIO 1–5000 CTR1 := 100
MOTOR FLA 0.2–5000 A FLA1 := 250
a
a
FLAn default settings are 50 A for secondary phase input current of 1 A.
TWO SPEED ENABLE Y, N E2SPEED := N
CT RATIO–2nd 1–5000 CTR2 := 100
MOTOR FLA–2nd 0.2–5000 A FLA2 := 250
a
NEUTRAL CT RATIO 1 –2000 CTRN := 100
NOTE:
Motor FLA settings are in
Primary Amperes.
NOTE:
The SEL-749M normally uses
settings CTR1 and FLA1. When setting
E2SPEED is Y and SPEED2 control
input is asserted, the relay uses CTR2
and FLA2 (see
Table 4.32 ).
Table 4.3 Voltage Settings
Setting Prompt Setting Range Setting Name := Factory Default
PHASE PT RATIO 1.00–250.00 PTR := 35.00
LINE VOLTAGE 100–30000 V VNOM := 4160
XFMR CONNECTION Delta, Wye DELTA_Y := DELTA
NOTE:
The line voltage setting
VNOM is line-line voltage in primary
volts.
Courtesy of NationalSwitchgear.com