Under Voltage and Over Voltage Effect on Motor Explained

Under Voltage and Over Voltage Effect on Motor Explained

Hey, in this article we are going to discuss the under-voltage and overvoltage effects on motors. We will discuss how a motor reacts during voltage variations or voltage fluctuations or the effect of voltage variation on the motor. Electric motors are a major part of electrical engineering and are used everywhere. There are different types of motors available. High-capacity motors are so costly, and their breakdown may cause a huge loss of production, and operation. So to properly maintain an electric motor we must be aware that it getting proper supply voltage and current. At the same time, we have to look at the voltage variation and should take the required precautions, and protective devices.

Under Voltage Effect on DC Motor

The working principle of the DC Motor is very straightforward. If the load on the motor is constant then the speed of the motor is directly proportional to the supply voltage. So when the supply voltage falls then the speed of the motor also be low. So during the under-voltage fault, the DC motor gets affected more. Of course, your mechanical load or the system connected to the motor will be affected. When the supply voltage suddenly falls the speed of the motor will suddenly fall down which can cause a big impact on the mechanical load.

Over Voltage Effect on DC Motor

DC Motor is a self-regulating machine due to its Back EMF Phenomenon. During the overvoltage fault, the DC motor is not affected more. When the supply voltage increases, the back emf on the motor also increases. We know that the back emf on the DC motor is always opposite to the supply voltage. So the back emf will oppose the flow of high current during overvoltage fault. Of course, if the supply voltage goes extremely high then the insulation of the motor coil will be damaged because insulation depends on voltage not current. 
Overvoltage causes the speed of the DC Motor high, so it may affect the mechanical load connected to the motor.

Effect of Voltage Variation or Fluctuation on DC Motor

Voltage variation or Voltage Fluctuation implies that the frequently falling and rising in supply voltage. Although the DC motor does not get more electrically affected due to voltage fluctuation but it may be damaged mechanically. That means its brushes, commutator, and bearing get damaged quickly. Because during the voltage fluctuation, the speed of the DC motor also fluctuates. Due to voltage fluctuation, the mechanical load connected to the motor will be affected. Sometimes sparking may happen on the brush.

Under Voltage Effect On Induction Motor(AC Motor)

An induction motor or AC motor works with completely different principles than a DC Motor. An induction motor works on the principle of electromagnetic induction or the same as a transformer or we can say an induction motor is a rotating transformer whose primary winding static and secondary winding rotating part. Also, note that the secondary winding or rotor of the induction motor is always closed-circuited. So, the same as the transformer principle, when the voltage is low, the current will be high, and when the voltage is high, the current will be low.

So, when the under-voltage fault occurs, the induction motor will draw a very high current, and due to the flow of the high current the coils will be overheated and it will be burned.

Over Voltage Effect on Induction Motor(AC Motor)

Now, if over-voltage occurs across an induction motor, then the insulation of the winding will be damaged because we know that the insulation of any conductor or wire can withstand a certain limit of voltage. So when a high voltage is applied the insulation will be damaged.

The overvoltage also causes to flow of high current in the primary or stator coil of the induction motor which may cause the burning of the winding.

Effect of Voltage Fluctuation or Variation on Induction Motor

Voltage fluctuation does not affect so much the operation of an induction motor but frequently voltage fluctuation can damage any machine. Generally, electrical motors are connected through many protective, switching, and sensing devices so before the motor gets affected, the circuit will be tripped. In the case of a three-phase machine, voltage unbalancing can be harmful to the machine.

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Under Voltage and Over Voltage Effect on Motor Explained Under Voltage and Over Voltage Effect on Motor Explained Reviewed by Author on March 28, 2021 Rating: 5
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