3.39
Date Code 20170601
Instruction Manual
SEL-387-0, -5, -6 Relay
Differential, Restricted Earth Fault, Thermal, and Overcurrent Elements
Thermal Element (SEL-387-6 Relay)
Estimated Time to Assert TLL Alarm
Estimated time to assert TLL bit:
Equation 3.31
Setting Descriptions
Thermal Element Enable (ETHER)
Range: Y, N
This setting enables or disables the thermal element. Set ETHER = Y to
enable the thermal element or ETHER = N to disable the thermal element. If
ETHER = N, the relay hides the following settings and they are unavailable to
the user.
Thermal Model Winding Current (TMWDG)
Range: 1, 2, 3, 4, 12, 34
The TMWDG setting determines which power transformer winding
corresponds with the measured currents the thermal element uses for
calculations.
The measured currents the thermal element uses must represent the total
current in or out of the power transformer. TMWDG allows selection of
Winding 1, Winding 2, Winding 3, Winding 4, Windings 1 and 2 (two currents
added together), or Windings 3 and 4 to be the current for the thermal element
calculations. Refer to the two configuration settings, E87W and EOC, to
determine which of the four windings are in use.
For a two-winding power transformer, current transformers located on either
the high-voltage or low-voltage side would provide the correct current values.
You can apply the thermal element on a three- or four-winding power
transformer, provided that the TMWDG setting represents the total current in
or out.
Winding LL Voltage (VWDG)
Range: 1–1000 kV, in 0.01 kV steps
Set VWDG to the rated phase-to-phase voltage for the winding you select in
the TMWDG setting. The relay uses VWDG in conjunction with the power
transformer MVA rating (see MCS setting) to calculate rated current. The
relay then divides measured current by the rated current to determine K, which
the relay uses in thermal element calculations.
where:
TLLt = estimated time to assert total loss-of-life alarm, in hours
TLOLL = total loss-of-life limit setting
TLOL = total accumulated loss of life, TLOL
RLOL = most recent daily rate of loss-of-life calculation
TLLt
TLOLL TLOL
–
RLOL
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24
•
=
Содержание SEL-387-0
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