Download - Daman and Diu Electricity Department, Government of ...
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2.5 SCOPE:<br />
06 SECTION II-: SPECIFIC TECHNICAL REQUIREMENT OF<br />
66KV PTS<br />
2.2.2 This section covers the specific technical requirements, climatic <strong>and</strong> isoccraunic conditions<br />
<strong>and</strong> systems particulars for which POTENTIAL transformers shall be <strong>of</strong>fered as per the<br />
general technical requirements given under section-I <strong>of</strong> this specification <strong>and</strong> the schedule <strong>of</strong><br />
requirements specified herein for various substations.<br />
2.6 CLIMATIC & ISOCERAUNIC CONDITIONS:<br />
2.6.1 The climatic conditions, under which the equipment shall operate satisfactorily are as<br />
follows:<br />
a) Maximum ambient temperature <strong>of</strong> air in Shade (C) 50C<br />
b) Minimum ambient temperature <strong>of</strong> air in shade (C) 4C<br />
c) Maximum daily average ambient temperature (C) 40C<br />
d) Maximum yearly average ambient temperature (C) 30C<br />
e) Maximum relative humidity (%) 95%<br />
f) Average number <strong>of</strong> thunderstorm days / annum. 15<br />
g) Average annual rainfall 150 cms.<br />
h) Maximum wind pressure 150 Kg/m2<br />
i) Height above mean seal level Not exceeding 1000mtrs.<br />
2.6.2 Since the substations may be near seashore, the equipment <strong>of</strong>fered shall be suitable for<br />
heavily polluted atmosphere.<br />
2.7 SYSTEM DETAILS:<br />
i) Nominal system voltage 66 KV<br />
ii) Maximum rated voltage 72.5 KV<br />
iii) Frequency 50Hz.<br />
iv) Number <strong>of</strong> phases 3<br />
v) Neutral earthing Solidly Earthed<br />
2.8 TYPE & RATING OF POTENTIAL RANSFORMER:<br />
2.8.1 The 66 KV Potential transformer shall have the rating as given below:<br />
1) PT Ratio : 66 kV / RT3 / / 110V / RT 3 / / 110V / RT3<br />
2) No <strong>of</strong> Cores : Two<br />
Core – I Core – II<br />
3) Application Metering protection<br />
3) Rated burden (VA) 100 50<br />
4) Class <strong>of</strong> accuracy CL 0.5 CL 0.5<br />
5) Voltage Factor : .2 continuous, 1.5 for 8 hours<br />
6) Max. temp. Rise over design Ambient<br />
Temp. at rated voltage & frequency : Max 50 over 50 Deg. Cent.<br />
7) 1.2 / 50 microsecond lightning impulse : 350<br />
withst<strong>and</strong> voltage (kV peak)<br />
8) Power frequency withst<strong>and</strong> voltage for : 140<br />
one minute (kV rms) dry & wet<br />
9) Minimum total for creepage distance for : 1810 mm<br />
heavily polluted atmosphere<br />
10) Reference st<strong>and</strong>ard for PTS : I.S 3156, 1992<br />
11) Reference st<strong>and</strong>ard for oil : I.S 335, 1993<br />
12) Max. temp. Rise over design Ambient<br />
Temp. at rated voltage & frequency : Max 50 over 50 Deg. Cent.<br />
13) The 66kv PTS shall be outdoor type, single phase, 50 HZ, oil filled, Hermetically<br />
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