Schweitzer Engineering Laboratories SEL-751 - Figure 5.8 METER MV Command Response; Figure 5.9 METER RMS Command Response; Table 5.5 RMS Meter Values

5.9
Date Code 20170927 Instruction Manual SEL-751 Relay
Metering and Monitoring
Metering
All maximum and minimum metering values are stored to nonvolatile
memory four times per day and within one minute of the maximum and
minimum metering values being reset.
Math Variable
Metering
The SEL-751 includes 32 math variables. When you receive your SEL-751,
no math variables are enabled. To use math variables, enable the number of
math variables (between 1 and 32) you require, using the EMV setting in the
Logic setting category. Figure 5.8 shows the device response to the METER
MV M(ath) V(ariable) command with 8 of the 32 math variables enabled.
RMS Metering
The SEL-751 includes root-mean-square (rms) metering. Use rms metering to
measure the entire signal (including harmonics). You can measure the rms
quantities shown in Table 5 . 5.
RMS quantities contain the total signal content including harmonics. This
differs from the fundamental meter (METER command) in that the
fundamental meter quantities only contain the fundamental frequency (60 Hz
for a 60-Hz system).
Figure 5.9 shows the METER RMS command.
=>>MET MV <Enter>
SEL-751 Date: 02/17/2011 Time: 12:32:10
FEEDER RELAY Time Source: Internal
MV01 1.00
MV02 -32767.00
MV03 -1.00
MV04 0.00
MV05 1000.59
MV06 -1000.61
MV07 2411.01
MV08 2410.99
=>>
Figure 5.8 METER MV Command Response
Ta b l e 5 . 5 RM S M eter Val u e s
Relay Option RMS Meter Values
All Models RMS current IA, IB, IC, and IN magnitudes
(A primary)
With AC Phase Voltage Inputs VAB, VBC, VCA or VAN, VBN, VCN magni-
tudes (V primary)
With Voltage/Arc-Flash Detection
2 AVI/4 AFDI Card Option
VS magnitude (V primary)
=>>MET RMS <Enter>
SEL-751 Date: 12/02/2010 Time: 15:45:49
FEEDER RELAY Time Source: External
IA IB IC IN
RMS (A pri.) 998.3 1080.5 963.2 0.0
VAB VBC VCA VS
RMS (V pri.) 6648 6707 7502 6741
=>>
Figure 5.9 METER RMS Command Response