IEEE Std C57.12.23:2002 pdf free download

IEEE Std C57.12.23:2002 pdf free download.IEEE Standard for Underground Type, Self-Cooled, Single-Phase, Distribution Transformers with Separable Insulated High-Voltage Connectors; High Voltage 25 000 V and Below; Low Voltage 600 V and Below; 167 kVA and Smaller.
Corrosion-resistant base bars or other suitable means shall be provided on the transformer tank to protect the bottom of the tank while in transit and when installed in the underground enclosure. Minimum bar height is 25 mm.
For the purpose o’ locating term inations and operating devices, the plan slew of the transformer is divided into four segments with the segments numbered in a clockwise direction. See I:igure I.
The lifting provisions shall be permanently attached and arranged on the tank to provide a distributed balanced lift in a vertical direction for the completely assembled transformer: they shall be designed to provide a safety factor of 5. This safety factor of 5 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.
6.2 Connectors and terminals
The electrical characteristics of the completely assembled high-voltage connectors shall be as shown in Table I. The electrical characteristics of the completely assembled low-voltage terminals shall be as shown in Table 2.
Separable insulated high-voltage connectors shall be provided for connection to the distribution system. The high-voltage connectors shall consist of either hushing wells, hushing wells wIth bushing inserts, or integral bushings, as specified. One cable accessory parking stand shall be provided for each phase of supplied high- voltage. For specific details concerning high-voltage separable connectors and cable accessory parking stands, refer to IEEE Std 36-l995.
Separable insulated high-voltage connectors that are designed for operation after the transformer is in place shall be located so that they can be operated with hot-line tools.
On phase-to-ground transformers, the H, end of the high-voltage winding shall be connected to the tank internally. This connection shall be independent of all other electrical connections.
Low-voltage cable leads extending 350 mm above the top of the cover shall be provided and arranged for vertical takeoff. Cable insulation shall be in accordance with ICEA S-66-524INEMA WC7 or functional equivalent for continuous operation at a minimum of 90 C and 600 V. Cable liesibility shall be such that bending it into an arc having a radius of 3(X) mm can be accomplished without ovcrMressing the low-voltage bushing. Cable sizes shall be as shown in Table 3.