IEEE C57.12.25-1990 pdf free.Pad-Mounted,Compartmental-Type,Self-Cooled,Single-Phase Distribution Transformers with Separable Insulated High-Voltage Connectors; High Voltage,34 500 GrdY/19 920 Volts and Below; Low Voltage,240/120 Volts; 167 kVA and Smaller Requirements.
IEEE C57.12.25 Voltage ratings shall be in accordancewith Table i and 6.2.1.For series-multipletransformers, the voltage change shall be madewith a switch handle located in the high-voltageportion of the terminating compartment.Thehandle shall be designed to prevent accidentaioperation by requiring a preliminary step be-fore the voltage setting can be changed. Actual voltages or position numbers corresponding to the nameplate shall be clearly identifiable near the handle. There shall be locatedon or adjacent to the operating mechanism acaution to deenergize the transformer beforeoperating.
Access to the termination compartmentshall be provided by a single door or by individual compartment doors. lf individual compartment doors are provided, they shall be soconstructed as to provide access to the highvoltage portion of the compartment only afterthe door to the lowvoltage portion of thecompartment has been opened. There shallbe one or more additional captive fasteningdevices that must be disengaged before thehighvoltage door can be opened. Where thelow-voltage compartment door is of a flat paneldesign, or where only a single door is provided,the door shall have threepoint latching with ahandle provided for a locking device. lf a lift up hood or a single door provides access toboth the highvoltage and lowvoltage portionsof the compartment,onepoint latching withprovision for a locking device shall be provided. (See Figure 3 for typical construction).6.1.3 The bottom edges of the compartmentshall be so constructed as to provide for theuse of hold-down devices accessible only frominside the compartment.
The construction of the unit shall be suchthat it can be lifted，skidded,or slid，or anycombination of these，into place on themounting surface without disturbing the high-voltage or low-voltage cables.
The transformer shall be arranged forrolling in two directions; parallel to and at rightangles to one side of the transformer.
The lifting provisions shall be arrangedon the tank to provide a distributed balancedliftin a vertical direction for the completelyassembled transformer and shall be designedto provide a safety factor of 5. The safetyfactor of 5 is the ratio of the ultimate stress ofthe material used to the working stress. Theworking stress is the maximum combined stressdeveloped in the lifting provisions by the staticload of the completely assembled transformer.IEEE C57.12.25 pdf download.