5.9
Date Code 20100129 Instruction Manual SEL-751A Relay
Metering and Monitoring
Metering
Arc-Flash Light
Intensity Metering
When the SEL-751A is ordered with the arc-flash detection (AFD) option
(order the 3 AVI / 4 AFDI card for slot E), the relay provides light metering
data with the METER LIGHT (METER L command) report. The light inputs
LS1–LS4 are given in percent of full scale.
Figure 5.11 provides an example of METER L (Light) command report.
=>>MET L<Enter>
SEL-751A Date: 12/01/2008 Time: 15:45:14
FEEDER RELAY Time Source: External
Light Intensity
LS1 (%) 2.4
LS2 (%) 1.9
LS3 (%) 0.7
LS4 (%) 2.3
=>>
Figure 5.11 Device Response to the METER L (Light) Command
Demand Metering
The SEL-751A offers the choice between two types of demand metering,
settable with the enable setting:
EDEM = THM (Thermal Demand Metering)
or
EDEM = ROL (Rolling Demand Metering)
The relay provides demand (METER DE command) and peak demand
(METER PE command) metering. Table 5. 6 shows the values reported.
Figure 5.12 provides an example of the METER DE (Demand) command
report and Figure 5.13 provides an example of the METER PE (Peak
Demand) command report. Refer to Demand Metering on page 4.76 for
detailed descriptions and settings selection.
=>>MET DE <Enter>
SEL-751A Date: 12/01/2008 Time: 15:44:58
FEEDER RELAY Time Source: External
IAD IBD ICD IGD 3I2D
DEMAND (A pri.) 874.3 907.9 832.1 85.6 56.8
LAST RESET = 12/01/2008 14:55:54
=>>
Figure 5.12 Device Response to the MET DE Command
Ta b le 5 .6 D e m a nd Va l u e s
Relay Option Demand/Peak Demand Values
Available With Voltage Card
Options …x73x… and
…x74x…
Demand/peak demand values of line currents IA, IB, and
IC magnitudes (A primary)
Demand/peak demand value of IG (residual ground cur-
rent) magnitude (A primary)
Demand/peak demand value of negative-sequence current
(3I2) magnitude (A primary)
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