SEL-451 Data Sheet
Schweitzer Engineering Laboratories, Inc.
14
1-second sync intervals, the relay can be synchronized to
an accuracy of ±100 ns. The relay is capable of receiving
as many as 32 sync messages per second.
SNTP Time Synchronization
Use simple network time protocol (SNTP) to cost-effec-
tively synchronize SEL-451 Relays equipped with Ether-
net communication to as little as ±1 ms with no time-
source delay. Use SNTP as a primary time source, or as a
backup to a higher accuracy IRIG-B time input to the
relay.
Substation Battery Monitor for DC
Quality Assurance
The SEL-451 measures and reports the substation battery
voltage for two battery systems. Two sets of programma-
ble threshold comparators and associated logic provide
alarm and control of two separate batteries and chargers.
The relay also provides dual ground detection. Monitor
DC system status alarms with an SEL Communications
Processor and trigger messages, telephone calls, or other
actions.
The measured dc voltage is reported in the METER dis-
play via serial port communications, on the LCD, and in
the Event Report. Use the event report data to see an
oscillographic display of the battery voltage. Monitor the
substation battery voltage drops during trip, close, and
other control operations.
Figure 19
Example PTP Network
SEL-487B
SEL-487E
SEL-411L
SEL-421
SEL-451
GPS
SEL-2488
SEL-2740M
Figure 20
SNTP Diagram
SEL-2401
SEL-3354
SEL-2725
SEL-487E
Table 3
Metering Capabilities (Sheet 1 of 2)
Capabilities
Description
Instantaneous Quantities
Voltages
V
A,B,C
(Y), V
A,B,C
(Z), V
3V0, V1, 3V2
0–300 V with phase quantities for each of the six voltage sources available as a separate
quantity.
Currents
I
A,B,C
(W), I
A,B,C
(X)
I
A
L, I
B
L, I
C
L, (combined currents)
IGL, I1L, 3I2L (combined currents)
Phase quantities for each of the two current sources available as a separate quantity or
combined as line quantities.
Power/Energy Metering Quantities
MW, MWh, MVAR, MVA, PF,
single-phase and three-phase
Available for each input set and as combined quantities for the line.
Demand/Peak Demand Metering
I
A,B,C
, 3I
2
, 3I
0
Thermal or rolling interval demand and peak demand.
MW, MVAR, MVA, single-phase
Thermal or rolling interval demand and peak demand.
MW, MVAR, MVA, three-phase
Thermal or rolling interval demand and peak demand.
