Schweitzer Engineering SEL-387-0, Instruction Manual, Page: 179 / 556

5.5
Date Code 20170601 Instruction Manual SEL-387-0, -5, -6 Relay
Metering and Monitoring
Metering Functions
=> METER SEC <Enter>
XFMR 1 Date: MM/DD/YY Time: HH:MM:SS.SSS
STATION A
Phase Currents Sequence Currents
Wdg1 IAW1 IBW1 ICW1 3I1W1 3I2W1 IRW1
I (A,sec) 123.12 123.12 123.12 123.12 123.12 123.12
Angle (deg) ±123.12 ±123.12 ±123.12 ±123.12 ±123.12 ±123.12
Wdg2 IAW2 IBW2 ICW2 3I1W2 3I2W2 IRW2
I (A,sec) 123.12 123.12 123.12 123.12 123.12 123.12
Angle (deg) ±123.12 ±123.12 ±123.12 ±123.12 ±123.12 ±123.12
Wdg3 IAW3 IBW3 ICW3 3I1W3 3I2W3 IRW3
I (A,sec) 123.12 123.12 123.12 123.12 123.12 123.12
Angle (deg) ±123.12 ±123.12 ±123.12 ±123.12 ±123.12 ±123.12
Wdg4 IAW4 IBW4 ICW4 3I1W4 3I2W4 IRW4
I (A,sec) 123.12 123.12 123.12 123.12 123.12 123.12
Angle (deg) ±123.12 ±123.12 ±123.12 ±123.12 ±123.12 ±123.12
The phase angles given are all referenced to current IAW1. That is, the full set
of 24 calculated current phasors is rotated in a manner that brings IAW1 to an
angle of zero degrees. However, if the magnitude of IAW1 is less than 0.05x
I
NOM
(0.25A for a 5 A relay), the angles are listed according to the phasor
calculation without further adjustment.
Demand Reset
Functions (MET RD
and MET RP
Commands)
The demand ammeter function performs an integration of current over time
and, as such, contains a “history” of the currents dating back minutes or hours
from the present time. The peak demand ammeter function maintains registers
with the highest recorded demands of each type over a period of time since the
last reset of the registers. For both of these functions, it may be desirable to
erase this “history.”
The MET RD n (Reset Demand) command returns the demand ammeter
current values to zero. This is useful during testing, for example, so that
previous test quantities do not appear as part of the metered values or in order
to check the shape of the rising exponential for a fixed current over a period of
time.
The MET RP n (Reset Peak demand) command stores the present values of
the demands, along with their associated date/time stamps, in the registers
used to store the values of the peaks. These become the new peaks of record
until higher values occur. This function might typically be performed on a
daily, weekly, or monthly basis to determine a peak demand profile of the
equipment over time.
Both of the reset commands must be followed by a value for “ n .” A value of 1,
2, 3, or 4 will produce a reset of all the demand or peak demand values for
Winding
n . If the letter A is entered, reset will be done on all of the windings.
Failure to enter a value will produce an
Invalid parameter
response from the
relay. For valid n values, the relay will ask for a
Yes/No
verification of your
request to reset. No reports are issued for either command.
Figure 5.1 is an overall diagram representative of the five demand ammeters
for each Winding n , and the relationship of the four related commands
( MET D , MET P , MET RD , MET RP ). The currents are indicated
generically as IX, the demand of each as XD(t), the peak demand of each
XD(t) as PXD, the three demand alarm thresholds as XDEM
n P, and the
associated Relay Word bit as XDEM n . The greatest of the XD(t) demands for
IAW n , IBW n , and ICW n is compared to the phase threshold PDEM n P; if the
threshold is exceeded, Relay Word bit PDEM n is set. Negative-sequence
current demand is compared to QDEM n P, and Relay Word bit QDEM n is set
if the threshold is exceeded. Residual current demand is compared to
NDEM
n P, and Relay Word bit NDEM n is set if the threshold is exceeded.