Schweitzer Engineering SEL-387-0, Instruction Manual

Page: 94 / 556

3.44
SEL-387-0, -5, -6 Relay Instruction Manual Date Code 20170601
Differential, Restricted Earth Fault, Thermal, and Overcurrent Elements
Thermal Element (SEL-387-6 Relay)
insulation aging acceleration factor, which, when multiplied by elapsed time,
provides an indication of the expected life remaining in the transformer.
Should load and temperature be greater than normal, this factor is greater than
1. Should load and temperature be less than normal, the factor is less than 1.
FAAL1 and FAAL2 determine limits for the aging acceleration factor. If the
aging acceleration factor exceeds the limits, the FAA1 or FAA2 bit asserts.
Using SEL
OGIC
control equations, you can configure these bits to close alarm
contacts.
With XTYPE = 1 and aging acceleration factors being calculated for each of
the three single phase transformers, the FAA1 or FAA2 bit asserts when any of
the three values exceeds the limits. The thermal report will show which
transformer was above the limits.
Daily Rate of Loss-of-Life Limit (RLOLL)
Range: 0–99%, in 0.01% steps
One of the outputs the thermal element provides is daily rate of loss of life.
This output is a measure, in percent, of the life lost from the relay during a
24-hour period. RLOLL determines a limit for daily rate of loss of life. If the
daily rate of loss of life exceeds the limit, a RLLOL bit asserts. Using
SEL
OGIC
control equations, you can configure the RLOLL bit to close an
alarm contact.
With XTYPE = 1 and daily rate of loss of life being calculated for each of the
three single-phase transformers, the RLL bit asserts when any of the three
values exceeds the limit. The thermal report will show which transformer
exceeded the limit.
Total Loss-of-Life Limit (TLOLL)
Range: 0–99%, in 0.01% steps
One of the outputs the thermal element provides is total loss of life, which is
an estimate of the accumulated loss of transformer insulation life as a
percentage of normal expected transformer insulation life. TLOLL determines
a limit for total loss of life. If the total loss of life exceeds the limit, a TLL bit
asserts. Using SEL
OGIC
control equations, you can configure the TLL bit to
close an alarm contact.
With XTYPE = 1 and aging acceleration factors being calculated for each of
the three single phase transformers, the TLL bit asserts when any of the three
values exceeds the limit. The thermal report will show which transformer
exceeded the limit.
Cooling System Efficiency Pickup (CSEPx)
Range: 5–100°C
When a measured top-oil temperature is available via the serial port, measured
currents are used to determine a calculated top-oil temperature. If the
measured top-oil temperature is greater than the calculated top-oil temperature
by the value of setting CSEP
x , then a Cooling System Efficiency, CSE, bit in
the Relay Word is asserted. Using SEL
OGIC
control equations, the CSE bit can
be configured to any of the relay outputs to perform alarm or tripping
functions. Assertion of the CSE bit indicates that the cooling system (fans and/
or pumps) is operating below expected efficiency and may require
maintenance.
NOTE:
If XTYPE = 3, x = 1.
If XTYPE = 1, x = 1, 2 and 3.