5.22
SEL-2414 Transformer Monitor Instruction Manual Date Code 20130214
Metering and Monitoring
Monitoring
Winding 3 LL Voltage (TMWNOM3)
Range: 0.20–1000.00 kV, in 0.01 kV steps
TMWNOM3 is used if ETHERM = W. Set TMWNOM3 to the rated phase-to-
phase voltage for the tertiary winding of the three-winding transformer that is
being monitored. The relay uses TMWNOM3 in conjunction with the
Transformer 3 MVA rating to calculate rated current. The relay then divides
measured current by the rated current to determine K (per unit load) that the relay
uses in thermal element calculations.
Transformer Winding Source Selection (TMWSEL)
Range: Z, E, AQ
TMWSEL setting allows the user to select the source of the current
measurements. Select Z if the current card is in Slot Z. Select E if the current card
is in Slot E. Select AQ to use analog quantities instead of a current card (in this
case, TMWAQ will need to be filled in).
Transformer Winding Source (TMWAQ)
Range: If ETHERM = 1, requires 1, 2, or 3 Analog Quantities.
If ETHERM = 3 or W, requires 3 Analog Quantities.
TMWAQ setting allows the user to select the analog quantities for use as current
measurement inputs to the thermal model. The analog quantities must be in
primary amps. When ETHERM = 3 or W, the first analog quantity will
correspond with the first transformer or winding, the second analog quantity will
correspond with the second transformer or winding, and the third analog quantity
will correspond with the third transformer or winding. These could be analog
inputs, remote analogs, or similar quantities. Using a measurement means other
than current magnitudes obtained from a current input card allows the thermal
model to be used without having a current card installed.
Winding Temp/Ambient Temp (THwr)
Range: 55°, 65°C
Rated winding rise over ambient temperature is the difference in degrees Celsius
of the winding temperature of a transformer above the ambient temperature. The
actual winding temperature will be between the top-oil and hot-spot temperature.
Most power transformers manufactured in 1977 and later are rated for a 65°C rise
over ambient. Power transformers manufactured prior to 1977 can be rated for a
55°C rise over ambient. Set THwr for either 55 or 65, based on the rating of the
power transformer.
This setting determines which set of default transformer constants from
Figure 5.15 the relay will use if EDFTC = Y.
Number of Cooling Stages (NUMCS)
Range: 1–3
Power transformers generally have a self-cooled rating and one or two stages of
forced cooling.
Cooling Stage 1 is typically defined as natural cooling (no fans). Cooling Stage 2
would include the first stage of cooling fans. Cooling Stage 3 would include both
first and second stage of cooling fans or cooling fans and oil circulation pump.
Set NUMCS to the maximum number of cooling stages associated with the
monitored power transformer.
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