IEEE Std C57.12.40 pdf free download

IEEE Std C57.12.40 pdf free download.Network, Three-Phase Transformers, 2500 kVA and Smaller; High Voltage, 34 500 V and Below; Low Voltage, 600 V and Below; Subway and Vault Types (Liquid Immersed).
5.3.4 Lifting lugs
Four tilling tugs shall be designed and arranged to facilitate lifting the transformer with the network protector attached. The lift lugs shall be designed for dual purpose—for lifting and for shipping tie-down purposes. The tugs shall be provided with a suitable hole for attaching a 40 mm (1.5 in) clevis. The lifting lugs shall be designed and placed such that an installed clevis will not damage the transfbrrner tank or cover when the lifting slings are at 60° from horizontal. The lifting lugs shall not extend past the plane of the network protector mounting flange less 1 inch to allow for soft sling lifting with the network protector bolted in place.
5.3.5 Lifting and jacking provisions
Lifting and jacking provisions shall be designed to provide a safety factor of five. This safety factor is the ratio of the ultimate stress of the material used to the working stress. The working stress is the maximum combined stress developed in the lifting provisions by the static load of the completely assembled transformer complete with the network protector.
5.4 Cooling panels
Cooling panels shall not extend beyond the tank wall on the secondary end of the transformer. Extensions on the liv end shall not interfere with, or block visibility of, the switch (and terminal) chamber operating mechanisms or accessories.
5.5 Primary switch chamber
5.5.1 Primary switch chamber cover
A bolted and gasketcd cover shall be provided for the switch chamber. The cover shall be equipped with handles and holes for guide pins. Where cemented gaskets are used, means for breaking the seal shall be provided.
5.5.1.1 Switch chamber fluid
When bushings or bushings wells (see 7.1) are supplied, the same type of liquid as in the transformer tank shall be supplied.
5.5.2 Primary switch operating positions markings
The three operating positions (Open, Closed, and Ground) shall be indicated by suitable permanent markings made of 300-series stainless steel or brass tags. No stenciling or decals shall be used. The markings shall be located near the external operating handle and be visible from the primary end of the transformer.
5.5.3 Operating handle
The switch-operating handle shall be provided with a mechanism to prevent accidental movement of the switch. Means shall be provided for padlocking the switch in each position. The maximum operating force on the handle shall not exceed 222 N (50 lbf). As a safety feature, the switch handle to shaft interface shall be designed so the external switch handle to shaft interface mechanism (handle or pins) breaks before any internal switch mechanism, including the interlocks, fails.
5.5.4 Switch chamber
The switch chamber shall be of a sealed construction, preventing the interchange of fluids between the switch chamber and the transformer tank.
5.5.5 Primary switch accessory equipment
The accessory equipment for the primary switch shall be provided and located approximately as shown in Figure 1.IEEE Std C57.12.40 pdf download.