Date Code 20020129
Metering and Monitoring
5-1
SEL-387E Instruction Manual
SECTION 5: METERING AND MONITORING
I
NTRODUCTION
The SEL-387E Relay provides metering information in several report formats, for each of the
three three-phase winding current inputs and three voltage inputs, and for the three differential
elements. A dc battery monitor reports on the supply voltage to the relay and can be
programmed to alarm for voltage excursions. There is also a breaker monitor function that keeps
track of breaker trips, the cumulative current interrupted over time, and the amount of estimated
contact wear. These functions and their associated reports are discussed in this section.
M
ETERING
F
UNCTIONS
There are three types of fundamental frequency metering functions in the SEL-387E Relay:
instantaneous, demand (thermal), and peak demand. Quantities metered include one set of phase
voltage and phase currents for each winding input; positive-, negative-, and zero-sequence
(residual) voltages and currents for all current and voltage inputs; and operate, restraint, second-
harmonic, and fifth-harmonic currents for the three differential elements. There are several
report formats, employing different groups of the above quantities, accessible by variants of the
METER
command through the relay serial port. This information is also available at the relay
front panel via the LCD.
There is also a specialized metering function, harmonic metering. This function provides a
snapshot of harmonic magnitudes of all analog inputs, fundamental through the 15th harmonic.
This section will discuss which quantities are used in each of the report formats and show the
format for each of the
METER
command displays, as they appear on the screen. The relay
front-panel LCD displays the same quantities but requires several stages of keystrokes to select
the data of interest. These displays are covered in
Section 8: Front-Panel Interface.
All METER displays herein show the default Analog Input Labels (IAW1, IBW1, etc.). Relay
displays show the user setting values of the Analog Input Labels.
Instantaneous Phase Meter Function (METER Command)
The
METER
(
MET
)
command, with no additional parameters, displays instantaneous current,
voltage, and power magnitudes, in primary quantities. Phase, positive-sequence, negative-
sequence, and residual currents and voltages are displayed for each of the three winding and
voltage inputs. Power is calculated from the supplied voltages and currents and displayed in
real, reactive, and apparent power quantities. Frequency, percent volts per hertz, and the value of
the station battery dc supply voltage at the relay are also included. The station battery voltage is
obtained from the Battery Voltage Monitor. If the command is typed as
MET m
, where m is any
number from 1 to 32767, the report will be repeated m times in succession. In this mode,
subsequent reports are not generated until the previous report has been completely sent.
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