How Does a Shunt Motor Work?

Updated March 23, 2017

The wiring in a motor is typically wired in two ways: in a series or in parallel. Parallel wiring is the wiring found inside a shunt motor; while a series motor's wiring connects to the armature in a series. The difference in wiring governs the way in which the motor will operate; for example, the wire in a shunt motor is thin and cannot produce as large of a current as the series motor.

Shunt Motor: At Work

Inside the shunt motor you'll find the armature; the armature is the rotating coil or coils. The shunt's armature, because it is connected in parallel, has high resistance and keeps the current flow low. The armature pulls the current to itself to create a magnetic field; the magnetic field powers the armature to begin rotating. As the armature turns it creates an electromagnetic field, the electromagnetic field causes the current to diminish; the armature will begin to pull the initial current based on the current load existing when the motor has reached its maximum speed.

Constant Current

The speed of a motor is measured in rounds per minute. The shunt motor's rounds per minute remains relatively constant once maximum rpm is reached because the armature is drawing in a constant amount of current needed to keep the coils turning without any increase or decrease.

Controlling the Current

The shunt motor's power can be controlled by alterations that cause an increase or decrease in the average rounds per minute. Artificially supplying more or less current to the armature affects the rotation of the armature, which directly affects the motor's rpm. If current load is increased the armature will slow, producing less of an electromagnetic field, and this will result in more current flow. The extra current flow will help the motor to regain the maximum rounds per minute.

The Difference Between Series and Shunt Motors

Put simply, the difference in the two basic motors is that the shunt motor is capable of maintaining a constant speed throughout various current and voltage loads. The series motor, however, will drop its rounds per minute when the initial current load decreases. A third type of motor: the compound motor, includes both parallel and series windings and is used to produce heavier loads (as with the series motor) and also to regulate the resulting rounds per minute (as with the shunt motor).

Shunt Motor Troubleshooting

When a shunt motor begins to malfunction, the motor will become excessively hot. The problems are normally easy to troubleshoot. Two main malfunctions to keep in mind are the loss of a voltage supply and/or a rupture in the armature winding; these are the first things to check if you a problem occurs with the shunt motor.

Shunt Motor Applications

The industrial and automotive fields use shunt motors extensively because specific levels of torque and speed are mandatory.

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