Understanding Dual-Voltage Motors: How One Motor Can Run at Two Rated Voltages?

Why Can Motors Operate at Two Rated Voltages?

Many motor applications require motors to operate in dual voltage mode, where the same motor can function normally at different rated voltages.

One common example is the 380/660V, dual voltage motors.

The insulation level of the winding and the current density of the conductor are the direct factors that determine the motor's rated voltage.

Some have questioned if different voltages would cause problems with the motor winding in dual voltage motors.

To address this, we must understand the essence of the normal operation of dual-voltage motors.

A dual voltage motor refers to a three-phase motor that has different rated line voltages under different connections. When the motor is in a star connection, the rated voltage is higher.

When in a triangle connection, the rated voltage is lower. However, the rated line voltage of the star connection must be the root of the rated line voltage of the triangle connection, and the triangle connection rated line current must be the root of the star connection rated line current three times.

The relationship between voltage and current analysis under different connection methods is explained in detail in another article.

The number of rated currents and rated voltages can differ significantly between the two connections, but this does not have adverse effects on the motor windings.

The essence of this lies in the relationship between the phase and line values of three-phase motors.

The reliability of motor winding insulation performance and conductor current density depends on the phase voltage and phase current of the winding.

When the motor uses the triangle connection method instead of the star connection method, the only change is the input motor line voltage.

According to the relationship between the voltage size under the two connection methods, when the motor uses the star connection and applies the root 3 times the line voltage of the rated line voltage of the triangle connection method, the phase voltage and phase current size of each phase of the motor winding do not undergo any changes.

Similarly, when the original star connection of the motor uses the triangle connection, the voltage must be reduced in accordance with the relationship between the voltage under the two connections to ensure the safety of motor operation.

In motor application practice, dual-voltage motors are typically used in three-phase asynchronous motors, where the higher voltage is used for the motor starting process, and the lower voltage triangle connection is used for normal motor operation.

Of course, dual-voltage motors can also handle the normal operation of different input power supply voltages (with the correct voltage matching).

Dengan terus mengetahui tentang topik ini, anda dapat meningkatkan pengetahuan anda dan kekal berdaya saing dalam landskap teknologi yang sentiasa berubah hari ini.

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