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Table For TF Parameters

This document provides specifications for a 3 phase power transformer including its ratings, parameters, insulation levels, temperature rise, and short circuit withstand capability. Key details include it being a 220/11.5kV transformer with a 13 step on-load tap changer, 55 degree K winding temperature rise, 850kV peak impulse withstand voltage, and ability to withstand a short circuit current of 15 times its rated current for 3 seconds.

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135 views3 pages

Table For TF Parameters

This document provides specifications for a 3 phase power transformer including its ratings, parameters, insulation levels, temperature rise, and short circuit withstand capability. Key details include it being a 220/11.5kV transformer with a 13 step on-load tap changer, 55 degree K winding temperature rise, 850kV peak impulse withstand voltage, and ability to withstand a short circuit current of 15 times its rated current for 3 seconds.

Uploaded by

mahnoor
Copyright
© © All Rights Reserved
We take content rights seriously. If you suspect this is your content, claim it here.
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Download as DOCX, PDF, TXT or read online on Scribd
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Sr Parameters Ratings

No.
1. No. of phases 3 Phase unit
2. No. of windings 2
3. Vector Group YNzn11
4. Frequency, Hz 50
5. Rated voltage of windings (Ur),
kV, rms.
i) High Voltage 220
Winding
ii) Low Voltage 11.5
Winding
6. Rated voltage ratio, kV, rms 220/11.5

7. Voltage tapping range + 10% in steps of


percent of rated voltage (by on- 0.77%
load tap changer)
8. No. of steps + 13
9. Rated highest voltage
(insulation class) kV, rms
i) High voltage 245
Winding
ii) Low voltage 17.5
winding
iii) Neutral end of 17.5
winding(s)

10. Method of system earthing Solidly earthed

11. Insulation levels:


i) Rated switching
impulse withstand
voltage phase-earth,
kV, peak
a) High voltage 850
winding
ii) Rated lightning
impulse withstand
voltage kV, peak
a) High voltage 950
winding.
b) Low voltage 95
winding

c) Neutral end
of winding(s) 95
iii) Line Terminal AC
Withstand Voltage.

a) High voltage
winding 460
b) Low Voltage
Winding 38

iv) Rated long duration


induced AC (ACLD) U1=255
withstand voltage as U2-226
per Clause 12.4 of IEC
60076-3,kV.

v) For Graded Winding:


a) Applied Voltage
Test, for neutral
kV,rms 140
b) Lightning Impulse
Withstand Voltage, 325
kVpeak
vi) Maximum partial
discharge, PC 300
12. Rated Power
i) ONAN rating for 12
phase transformer
MVA, at all taps.
ii) ONAF rating for
three phase transformer 20
MVA, at all taps.
iii) Overload rating for
three phase transformer As recommended
MVA at all taps by IEC.
13. Temperature Rise
i) Windings (measured by 55
resistance), degree K
iii) Top oil (measured by 50
thermometer), degree K

14. Short-circuit Withstand Capability


i) Maximum short circuit
current as multiple of
winding rated current,
symmetrical, rms
value:
a) for HV winding
b) for LV winding 15
ii) Duration of short- 25
circuit current, sec. 3

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