IEEE C57.12.34-2004 – Standard for Requirements for Pad-Mounted, Compartmental-Type, Self-Cooled, Three-Phase DistributionTransformers, 2500 kVA and Smaller: High-Voltage, 34 500GrdY/19 920 Volts and Below; Low Voltage, 480 Volts and Below.
Abstract: Certain electrical, dimensional, and mechanical characteristics are set forth as well as certain safety features of three-phase, 60 Hz, mineral-oil-immersed, self-cooled, pad-mounted, compartmental-type distribution transformers. These transformers are rated 2500 kVA and smaller, with high-voltages of 34 500 GrdY 119 920 volts and below, and with low-voltages of 480 volts and below. This standard covers the connector, bushing and terminal arrangements for radial or loop feed systems. This standard does not cover the electrical and mechanical requirements of any accessory devices that may be supplied with the transformer.
Keywords: compartmental, connector arrangements, loop, pad mounted, radial, three phase, three-phase pad-mounted distribution transformers, transformer.
IEEE C57.12.34 is intended for use as a basis for determining performance. interchangeability, and safety of the equipment covered, and to assist in the proper selection of such equipment.
IEEE C57.12.34 covers certain electrical, dimensional, and mechanical characteristics and takes into consideration certain safety features of three-phase. 60 Hz, mineral-oil-immersed, self-cooled, pad- mounted, compartmental-type distribution transformers. These transformers are rated 2500 kVA and smaller, with high-voltages of 34 500 GrdY/ 19 920 volts and below, and with low-voltages of 480 volts and below. These transformers are generally used for step-down purposes from an underground primary cable supply. This standard covers the connector, bushing and terminal arrangements for radial or ioop feed systems. Either certain minimum dimensions (see Figures 1, 2, 3, 7, 8. and 11) or certain specific dimensions (see Figures 4, 5, 6, 9, 10, and 12) shall be specified. This standard does not cover the electrical and mechanical requirements of any accessory devices that may be supplied with the transformer.
NOTE—Refer to latest USA federal regulations concerning PCB contamination in transformers.
4.2 Voltage ratings
Voltage ratings shaH be in accordance with Table I of this standard,
4.3 Tap ratings
When specified, high-voltage taps shall be as given in Table 2 of this standard. The tap changer handle or the area next to the handle in the terminating compartment shall be marked indicating suitability for deenergized operation only.
5. Basic lightning impulse insulation levels
Basic lightning impulse insulation levels (BILs) shall be in accordance with Table 1, Table 3, and Table 4 of this standard.
6. Dielectric test levels
Dielectric test levels shall be in accordance with the distribution levels in Table 5 of IEEE Std C57.12.00.