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 />
1.20.1.6 An oil flow indicator with alarm c<strong>on</strong>tacts shall be furnished with each pump<br />
assembly to indicate normal pump operati<strong>on</strong> and directi<strong>on</strong> of oil flow.<br />
1.20.1.7 Fans or blowers for air blast cooling shall be mounted so as to ensure that no<br />
damage to the coolers can arise from vibrati<strong>on</strong> of the fans. Wire mesh screens shall<br />
be fitted to prevent accidental c<strong>on</strong>tact with the blades, the mesh being not greater<br />
than 2.5 cm.<br />
1.20.1.7(a) The fan or blowers wiring shall be in such a way that any fan can be operated of<br />
group II or stand by<br />
1.20.1.8 In cases of ONAN/ONAF/OFAF type cooling, the transformer shall be capable of<br />
giving a c<strong>on</strong>tinuous output of at least 50% of rated full output with all the artificial<br />
cooling out of service and without exceeding the temperature rise. In case of<br />
ONAN/ONAF type of cooling the transformer shall be capable of giving c<strong>on</strong>tinuous<br />
output of at least 75% of the rated full output with the artificial oil force cooling out<br />
of service and without exceeding temperature rise. In case of ONAN or ONAF type<br />
of cooling the transformer shall have two sets of radiators.<br />
1.20.1.9 For OFAF cooled transformers with ONAN rating, piping system shall permit<br />
bypassing of oil pump and operati<strong>on</strong> of the transformer at its ONAN rating, in case<br />
forced oil system develop any troubles.<br />
1.20.1.10 ONAN/ONAF/OFAF cooled transformers shall be designed to operate at no load for<br />
4 hours without any cooler unit in service. ONAN/ONAF cooled transformers shall<br />
also be capable of delivering its rated MVA for 20 minutes with the loss of all<br />
cooling equipment while the transformer is carrying full load.<br />
1.20.1.11 The cooling calculati<strong>on</strong> shall be furnished with radiator drawing of specified<br />
temperature rise.<br />
1.20.1.12 The cooling fan shall be operated at 2 sets of temperatures for fan GR I & GR II.<br />
The oil pump shall be also operated by WTI.<br />
1.20.2 NATURAL OIL COOLED TRANSFORMER<br />
1.20.2.1 The radiating secti<strong>on</strong>s/tubes provided shall have sufficient cooling surface to limit<br />
the temperature rise to the values specified under clause – 1.13 of this specificati<strong>on</strong>.<br />
The radiating secti<strong>on</strong>s/tubes shall be c<strong>on</strong>nected to the tank cooler assembly headers<br />
by machined steel flanges with adequate gaskets to avoid oil leakage. Each radiator<br />
unit shall be provided with positive operated butterfly and lockable – n<strong>on</strong><br />
interchangeable type oil leak proof shut-off valve, which can be fastened in either<br />
closed or open positi<strong>on</strong>. A separate oil tight flange shall be provided for each tank<br />
c<strong>on</strong>necti<strong>on</strong>s for use when the radiator unit or cooler assembly is detached. It shall be<br />
possible to take out any of the radiating tubes without disturbing the transformer.<br />
Sign and Seal of Bidder Page 21 of 87
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