GE t60 Instruction Manual page 206

5.4 SYSTEM SETUP
• PHASE COMPENSATION: Selects the type of phase compensation to be performed by the relay. If set to "Internal
(software)", the transformer phase shift is compensated internally by the relay algorithm. If set to "External (with CTs)",
the transformer phase shift is externally compensated by the CT connections.
• LOAD LOSS AT RATED LOAD: This setting should be taken from the transformer nameplate. If not available from the
nameplate, the setting value can be computed as
the three-phase series resistance. The setting is used as an input for the calculation of the hottest-spot winding tem-
perature.
• RATED WINDING TEMP RISE: This setting defines the winding temperature rise over 30°C ambient temperature. The
setting is automatically selected for the transformer type as shown in the table below.
The loss of life function calculates the insulation aging acceleration factor using the settings entered in this section, by
following equation:
Θ
where is the rated hottest-spot temperature as per the table below,
H_R
Θ
and is the actual computed winding hottest-spot temperature.
H t ( )
The aging acceleration factor is computed every minute. It has a value of 1.0 when the actual winding hottest spot tem-
perature is equal to the rated temperature, is greater than 1 if the actual temperature is above the rated temperature,
and less than 1 if the actual temperature is below the rated temperature.
RATED WINDING
TEMPERATURE
Oil 55°C
5
65°C
Dry 80°C
115°C
150°C
• NO LOAD LOSS: This setting is obtained from the transformer data and is used to calculate the aging acceleration
factor.
• TYPE OF COOLING: The setting defines the type of transformer cooling and is used to calculate the aging accelera-
tion factor. The values and their description for this setting are as follows:
"OA": oil-air
"FA": forced air
"Non-directed FOA/FOW": non-directed forced-oil-air/forced-oil-water
"Directed FOA/FOW": directed forced-oil-air/forced-oil-water
"Sealed Self Cooled", "Vented Self Cooled", "Forced Cooled": as named
• TOP OIL RISE OVER AMBIENT: This setting should be available from the transformer nameplate data
• THERMAL CAPACITY: The setting should be available from the transformer nameplate data. If not, refer to the follow-
ing calculations. For the "OA" and "FA" cooling types:
C = 0.06 (core and coil assembly in lbs.) + 0.04 (tank and fittings in lbs.) +1.33 (gallons of oil), Wh/°C; or
C = 0.0272 (core and coil assembly in kg) + 0.01814 (tank and fittings in kg) + 5.034 (L of oil), Wh/°C
For the "Non-directed FOA/FOW" (non-directed forced-oil-air/forced-oil-water) or "Directed FOA/FOW" (directed
forced-oil-air/forced-oil-water) cooling types, the thermal capacity is given by:
C = 0.06 (core and coil assembly in lbs.) + 0.06 (tank and fittings in lbs.) + 1.93 (gallons of oil), Wh/°C; or
C =0.0272 (weight of core and coil assembly in kg) + 0.0272 (weight of tank and fittings in kg) + 7.305 (L of oil), Wh/°C
For dry-type power transformers:
5-74
2
P = I
(
R n W
⎛
15000
---------------------------- - – --------------------------- -
⎝
Θ Θ
+ 273
t ( )
H_R
F = e
AA
POWER NORMAL LIFE
CAPACITY EXPECTANCY
≤ 500 kVA
180000 hrs
≤ 100 MVA 6.5 × 10 4
hrs
≤ 500 kVA
20 years
≤ 100 MVA 6.5 × 10
4
hrs
6.5 × 10
4
> 100 MVA hrs
Any 20 years
Any 20 years
Any 20 years
T60 Transformer Protection System
×
R , where I is the winding rated current and R is
) ( )
n W
⎞
15000
⎠
+ 273
H t ( )
AT Θ
H_R
95°C
95°C
110°C
110°C
110°C
140°C
175°C
210°C
5 SETTINGS
(EQ 5.8)
GE Multilin