12 Leads Terminal Wiring Guide for Dual Voltage Star (Wye) Connected AC Induction Motor

Another convention of wiring connection for the AC induction motor apart from the 9 leads and the widely known 6 leads terminal is the 12 leads motor wiring connection. This can be determined directly by counting the number of available terminal leads accessible from the induction motor's terminal box.

All 12 leads motors are most commonly made for dual voltage application. This means that the motor was specifically designed for dual voltage operation which can be supplied with either low voltage or high voltage configuration. The motor will have to be appropriately selected accordingly, which is basically dependent on the application for which the motor is intended to operate based on the available source voltage where the motor is to be installed.

For the purpose of providing an example, the most common operational voltage for induction motors in most industrial application are motors designed to operate with 220 and 440 volts power supply. The rated operational voltage of any induction motors can be found from the motor's nameplate. It is also a standard practice for motor manufacturers to provide information about the motor's specific wiring connection for both low and high voltages on the motor's nameplate or on the cover of the motor's terminal box.

Each of the rated voltage values intended for the motor's operation requires different methodology of wiring connection in order to run the motor in either low or high volts operation. The electrical drawings shown below illustrates a standard 12 leads wiring connection for induction motors rated with dual voltage functionality in star (wye) configuration.

Fig-1: 12 Leads 3 Phase High Volts Star (Wye) Connected Motor Configuration

To connect the motor to its rated high voltage configuration, Fig-1 above shows an electrical schematic diagram of a star (wye) configured 12 leads motor so connected for a 440 volts AC power supply. The 3 phase AC source line voltage L1 is connected to the motor terminal 1, line voltage L2 is connected to motor terminal 2 and finally line voltage L3 is connected to motor terminal 3, while also shorting together motor terminals 10-11-12 to form the center tap of a typical star (wye) connection, then also individually joining together motor terminals 4-7 then 5-8 and finally 6-9 respectively (refer to above drawing).

Fig-2: 12 Leads 3 Phase Low Volts Star (Wye) Connected Motor Configuration

To connect the motor to its rated low voltage configuration, Fig-2 above shows an electrical schematic diagram of a star (wye) configured 12 leads motor so connected for a 220 volts AC power supply. The 3 phase AC source line voltage L1 is connected to the motor terminals 1-7, line voltage L2 is connected to motor terminals 2-8 and finally line voltage L3 is connected to motor terminals 3-9, while also shorting together motor terminals 4-5-6 including motor terminals 10-11-12 to form the center tap of a typical star (wye) connection (refer to above drawing).

Another variation of wiring configuration for a 12 leads motor connection apart from the 12 leads star (wye) connection is the 12 leads delta wiring configuration.