Specifications

Large Industrial Facility Even in large industrial facilities, supply voltage must be

Power Distribution Example reduced to a level that can be used by most electrical

equipment. While some machines require voltages above 480

volts, most factories use AC motors, drives, motor control

centers, and other devices that operate on 3-phase, 480 volts

and other equipment that requires even lower 1-phase or 3-

phase voltages.

In the example shown in the following illustration, power is

stepped down at the utility company’s substation to 38,000 volts

and applied to the incoming section of the industrial plant’s 38

kV medium voltage metal-clad switchgear.

One distribution branch is stepped down to 4160 volts and

another to 13,800 volts and further distributed through MV

metal clad switchgear units. A 13,800 volt branch is applied to

a secondary unit substation and further reduced to 480 volts.

Further down this path, a 1-phase transformer reduces the

voltage to 120 volts.

Transmission

Voltage

38 kV

MV Metal Clad Switchgear

Utility Substation

38 kV

4.16 kV

13.8 kV

MV Metal Clad Switchgear

Secondary Unit Substation

Primary

Switch

Switchboard or

LV Switchgear

480 V

120 V

Panelboard

Switchboard

Transformer

480 V

Panelboard

Transformer

480 V