GE T35 Instruction Manual page 208

5.4 SYSTEM SETUP
The general transformer settings apply to all windings. Settings specific to each winding are shown in the following section.
• NUMBER OF WINDINGS: Selects the number of windings for transformer 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:
5

where is the rated hottest-spot temperature as per the table below,
H_R

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
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
• 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:
5-74
TOP-OIL RISE OVER
MESSAGE
AMBIENT:
THERMAL CAPACITY:
MESSAGE
100.00 kWh/°C
WINDING THERMAL TIME
MESSAGE
CONSTANT: 2.00 min
t  
F e
=
AA
POWER NORMAL LIFE
CAPACITY EXPECTANCY
 500 kVA
 100 MVA
 500 kVA
 100 MVA
> 100 MVA
Any
Any
Any
T35 Transformer Protection System
Range: 1 to 200°C in steps of 1
35°C
Range: 0.00 to 200.00 kWh/°C in steps of 0.01
Range: 0.25 to 15.00 min. in steps of 0.01
2

P I R , where I
=
  
R n W n W
 15000 15000 
---------------------------- - --------------------------- -
–
 
 
273 273
+ +
H_R H t  
AT 
H_R
180000 hrs 95°C
4
6.5  10
hrs 95°C
20 years 110°C
4
6.5  10
hrs 110°C
4
6.5  10
hrs 110°C
20 years 140°C
20 years 175°C
20 years 210°C
5 SETTINGS
is the winding rated current and R is

GE Multilin
(EQ 5.7)