220-66-kv-xmer-on-line-nifes-r4-sept-08 - Gujarat Electricity Board
220-66-kv-xmer-on-line-nifes-r4-sept-08 - Gujarat Electricity Board
220-66-kv-xmer-on-line-nifes-r4-sept-08 - Gujarat Electricity Board
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GETCO/E/TS – XMER01power/R4 Sept <strong>08</strong><br />
(a)<br />
(b)<br />
(c)<br />
Diaphragm used shall be suitable for c<strong>on</strong>tinuous operati<strong>on</strong> in an atmosphere<br />
of 100 0 C to which transformer oil is likely to rise.<br />
The c<strong>on</strong>necti<strong>on</strong> of the air cell to the top of the reservoir shall be by an air<br />
proof seal permitting entrance of air into the cell <strong>on</strong>ly.<br />
The diaphragm of the c<strong>on</strong>servator shall withstand the vacuum during<br />
installati<strong>on</strong> and maintenance. Otherwise provisi<strong>on</strong> shall be made to isolate<br />
the c<strong>on</strong>servator from main tank during vacuum by providing vacuum sealing<br />
valve in the pipe c<strong>on</strong>necting the main tank with the c<strong>on</strong>servator.<br />
1.19 BUSHINGS:<br />
1.19.1 The bushings shall have high factor of safety against leakage to ground and shall be<br />
so located as to provide adequate electrical clearances between bushings and<br />
grounded parts. Bushings of identical voltage rating shall be interchangeable. All<br />
bushings shall be equipped with suitable terminals of approved type and size & shall<br />
be suitable for bimetallic c<strong>on</strong>necti<strong>on</strong>. The insulati<strong>on</strong> class of the high voltage neutral<br />
bushing shall be properly coordinated with the insulati<strong>on</strong> class, of the high voltage<br />
winding.<br />
1.19.2 Each bushing shall be so coordinated with the transformer insulati<strong>on</strong> so that all flash<br />
over will occur outside the tank.<br />
1.19.3 All main winding and neutral leads shall be brought out through “out door” type<br />
bushings which shall be so located that the full flashover strength will be utilized and<br />
the adequate phase clearance shall realised.<br />
1.19.4 All porcelain used in bushings shall be of the wet process, homogeneous and free<br />
from cavities or other flaws. The glazing shall be uniform in colour and free from<br />
blisters, burrs and other defects.<br />
1.19.5 The bushings for <str<strong>on</strong>g>66</str<strong>on</strong>g> kV and above shall be of the oil filled c<strong>on</strong>denser type<br />
(hermetically sealed) and shall c<strong>on</strong>form to the latest editi<strong>on</strong> of IS: 2099 & IS: 3347.<br />
36 kV bushings for neutral shall be solid porcelain or oil communicating type.<br />
Dimensi<strong>on</strong>s shall c<strong>on</strong>firm to IS: 2099 & IS: 3347 (Part – V). The characteristics of<br />
the oil used in the bushings shall be the same as that of the oil in the transformer.<br />
Oil filled c<strong>on</strong>denser type bushing shall be provided with fittings viz. oil level<br />
gauge, oil filling plug, Tap for capacitance and delta test, etc.<br />
1.19.6 All bushings shall have puncture strength greater than the dry flashover value.<br />
1.19.7 Main terminals shall be solder-less terminals and shall be suitable for ‘ACSR<br />
MOOSE’ c<strong>on</strong>ductor. The spacing between the bushings must be adequate to prevent<br />
flash over between phases under all c<strong>on</strong>diti<strong>on</strong>s of operati<strong>on</strong>.<br />
1.19.8 Special adjustable arcing horns may also be provided for the bushings as per IS:3716<br />
– 19<str<strong>on</strong>g>66</str<strong>on</strong>g>.<br />
Sign and Seal of Bidder Page 19 of 87
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