The difference between triangle connection and star connection How to test the triangle connection of three-phase motor

The difference between triangle connection and star connection

Both the triangle connection and the star connection are the connection methods of three-phase AC motors. The main difference lies in the different connection methods of the motor coils.

In the triangle connection method, the three coils of the motor are connected in pairs to form a triangle, and the three vertices are connected to the three-phase power lines respectively, as shown in the figure:

In the star connection, one end of each coil of the motor is connected to a common node, and the other end is connected to the corresponding phase line, as shown in the figure:

The two connections produce different voltage and current waveforms when the motor is running, so different factors need to be considered when using them, such as power, efficiency, starting characteristics, etc. Generally speaking, the star connection has better performance at starting and under low load conditions, while the delta connection is more stable under high load conditions.

How to test the triangle connection of three-phase motor

To test whether the three-phase motor triangle connection is normal, you can use the following steps:

Determine the three-phase power supply voltage and current: Use a voltmeter and an ammeter to measure the voltage and current of the three-phase power supply respectively to ensure that the power supply voltage and current are normal.

Check the motor coil insulation: Use an insulation resistance tester or a multimeter to perform insulation tests at both ends of the motor coil to ensure that the coil insulation is normal.

Check the motor wiring: Use a multimeter or clamp-type ammeter to check whether the motor wiring is correctly connected, including whether the three coils and three power lines are connected in a triangle.

Test the motor start: Connect the motor to a three-phase power source, turn on the power switch, and observe whether the motor can start normally. If the motor makes an abnormal sound or vibration when starting, it may indicate a wiring error or motor failure.

Test the motor running load: Use a load tester or dynamometer to test the operation of the motor under load, observe whether the motor can work normally, and check whether the motor's power, efficiency and other parameters are normal.

If a problem is found in the motor wiring during the test, the motor wiring needs to be rechecked and repaired. If there are other faults in the motor, further inspection and repair are required. It is recommended to use appropriate safety measures, such as wearing insulating gloves and goggles, to ensure safety when testing and repairing the motor.