IEEE Std C57.12.38 pdf free download

IEEE Std C57.12.38 pdf free download.Pad-Mounted-Type, Self-Cooled, Single-Phase Distribution Transformers 250 kVA and Smaller: High Voltage, 34 500 GrdY/19 920 V and Below; Low Voltage, 480/240 V and Below.
7.6 Lifting
The construction of the unit shall be such that it can be lifted, skidded, or slid, or any combination of these, into place on the mounting surface without disturbing the high-voltage or low-voltage cables (for example, removable sill). The lifting provision shall be 5/8 in-I 1 UNC threaded nut.
a) The transformer shall be arranged for rolling in two directions: parallel to and at right angles to one side of the transformer.
b) The transformer shall be provided with lifting provisions permanently attached and arranged on the tank to provide a distributed balanced lift in a vertical direction for the completely assembled transformer and shall be designed to provide a safety factor of five. The safety factor of five is the ratio of the ultimate stress of the material used to the working stress. The satty fictor is based on using all lifting provisions as instructed by the manufacturer.
8. Connectors, bushings, and terminals
8.1 Electrical characteristics
The electrical characteristics of the completely assembled high-voltage connectors, high-voltage bushings, and low-voltage terminals shall be as shown in Table 2 and Table 3 of this standard.
8.2 High-voltage terminals
8.2.1 General
The number, location, and arrangement of the high-voltage connectors shall be as shown in Figure 1 through Figure 4 and for high-voltage bushings as shown in Figure 5.
8.2.2 Reparability
The high-voltage terminals, whether bushing wells, bushing wells and inserts, integral bushings, or bushings, shall be externally replaceable. The inside terminal connections shall be externally removable through the connector’s opening in the transformer tank, or accessible through a handhole to permit removal and replacement.
8.2.3 High-voltage terminals using separable insulated high-voltage connectors
The high-voltage connectors shall consist of either bushing wells and bushing inserts or integral bushings, as specified. Cable accessory parking stands shall be provided. For specific details concerning high-voltage separable connectors and cable accessory parking stands, refer to IEEE Sid 386. 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.
8.2.5 High-voltage neutral The H2 end of the high-voltage winding shall be securely connected internally to the grounded clamping structure or to the tank. This connection shall be independent of all other electrical connections.
8.3 Low-voltage terminals
8.3.1 General The low-voltage line and neutral terminals for Type 1 transformers (see Figure I and Figure 2) shall be in accordance with Figure 6, Detail“A.” The low-voltage line and neutral terminals for Type 2 transformers (see Figure 3 and Figure 4) shall be in accordance with Figure 6, Detail“A” or Detail“B,” or Figure 7, Detail“C,”as specified. The low-voltage line and neutral terminals for transformers with HV bushings (see Figure 5) shall be in accordance with Figure 6, Detail “A.”” Low-voltage line and neutral terminal arrangements shall be as shown in Figure 8 and Figure 9.
8.3.2 Reparability Low-voltage bushings shall be externally replaceable. Inside terminal connections shall be externally removable through the connector s opening in the transformer tank or accessible through a handhole to permit removal and replacement.IEEE Std C57.12.38 pdf download.