W-T-631C, FEDERAL SPECIFICATION: TRANSFORMER, POWER DISTRIBUTION (04-JUN-1964) [NO S/S DOCUMENT]

W-T-631C, FEDERAL SPECIFICATION: TRANSFORMER, POWER DISTRIBUTION (04-JUN-1964) [NO S/S DOCUMENT]., This specification covers single-phase and three-phase 60 cycle, overhead type, liquid-immersed, air-cooled, distribution power transformers rates 500 kv.-a and smaller; high-voltage, 67,000 volts, and below; low voltage 15,000 volts and below.