This standard covers certain electrical, dimensional, and mechanical characteristics and takes into consideration certain safety features of three-phase, 60 Hz, liquid-immersed, self-cooled, submersible transformers with separable insulated high-voltage connectors. These transformers are rated 3750 kVA and smaller with high voltages of 34 500 GrdY/19 920 V and below and with low voltages of 600 V and below. These transformers are generally used for step-down purposes from an underground primary cable supply. These transformers are typically installed in an enclosure below ground level, operated from above and suitable for continuous submerged operation. This standard is intended for use as a basis for establishing the performance, electrical and mechanical interchangeability, and safety of the equipment covered, and to assist in the proper selection of such equipment. Revision Standard - Superseded. Certain electrical, dimensional, and mechanical characteristics are covered in this standard. It also takes into consideration certain safety features of three-phase, 60 Hz, liquid-immersed, self-cooled, submersible transformers with separable insulated high-voltage connectors. These transformers are rated 3750 kVA and smaller with high voltages of 34 500 GrdY/19 920 V and below and with low voltages of 600 V and below.