Table 71: Suggested maximum temperature limits
Type of
temperature
Normal life
expectancy loading
Planned loading
beyond nameplate
rating
Long term loading
Short term loading
Insulated winding
hot spot
temperature in °C
120
130 140 180
Top oil
temperature in °C
105 110 110 110
IEEE standard has also suggested the limits of temperature and load for loads higher
than transformer nameplate.
• For distribution transformers with 65°C hot spot temperature rise:
• Top oil temperature = 120°C
• Hot spot winding temperature = 200°C
• Short-time loading (1/2 h or less) = 300%
• For power transformer with 65°C hot spot temperature rise:
• Top oil temperature = 110°C
• Hot spot winding temperature = 180°C
• Maximum loading = 200%
Settings related to warning and alarm are:
WrnHPTmpLev1: This setting is used to set the level 1 value for hot spot temperature
warning.
WrnHPTmpLev2: This setting is used to set the level 2 value for hot spot temperature
warning. This should be more than the WrnHPTmpLev1 setting.
tDelayToAlarm1: This setting is used to set the time delay for the level 1 hot spot
temperature alarm. This time setting can be less than the winding time constant. For
example if the winding time constant is 420 sec, this setting can be 400 sec.
tDelayToAlarm2: This setting is used to set the time delay for the level 2 hot spot
temperature alarm. This should be less than time setting in tDelayToAlarm1.
17.10.3 Setting example
17.10.3.1 Transformer Rated Data
Table 72: Transformer Rated Data
Parameter
Value Note
Frequency 50 Hz
Rated Power 500 MVA / 500 MVA / 20 MVA
Voltage ratio 415 kV / 230 kV / 20 kV
Table continues on next page
1MRK 502 071-UEN - Section 17
Monitoring
Generator protection REG670 2.2 IEC and Injection equipment REX060, REX061, REX062 665
Application manual
To Next Page
Loading...
