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Overvoltage & Undervoltage: All You Need To Know

When your equipment encounters premature failure or performance issues –  several causes like corrosion, misalignment, bearing failure and metal fatigue come to mind.

However, at times it isn’t the system which is at fault – you too have a part to play when your equipment is experiencing a breakdown.

In this case, an incorrect voltage specification could be the reason for your equipment failure. But how exactly does too much or little voltage impact your equipment? Or why is the impact so consequential on your machinery?

Below, we will explain what overvoltage and undervoltage is so you can better understand why there remains a need to avoid either situation.


Often, there is a misconception where a voltage higher than the usual rated voltage amount is equivalent to higher output or efficiency. In reality, it is not the case and it only results in more harm than good.

Before we proceed into the details on why it is damaging for your equipment – what is overvoltage? To be more precise, its when a supply voltage of 10 percent and above the rated motor voltage occurs, as seen from the listed standards.

When overvoltage first occurs, it will usually impact the sensitive system components – motherboards and circuit boards. All these tiny electronic circuits are unable to cope with any extra voltage and current peaks. Additionally, it also leads to overheating due to the conversion of extra heat instead of operational output like torque. All these heat will continue accelerating and eventually cause the deterioration of bearing and insulation systems.


Undervoltage happens when the average voltage of equipment falls below the rated voltage amount. Frequent undervoltage can result in a degradation in equipment performance and reliability.

The winding suffers a substantial amount of wear and tear in the winding and reduces the lifespan of the equipment. Why? Insufficient voltage means that the equipment has to draw extra current in order to meet the power requirements. As a result of being unable to fulfil these needs – the equipment is not able to perform as how it normally does.

Especially if the scale of application for the equipment is used on industries and transmission distribution, the consequences are even dire as the generators, transformers, compressors, loads and static capacitors connected to the grid are programmed to operate at the specified voltage and at maximum load as much as possible.

When it’s not running on the rated voltage, the equipment won’t be operating at its best ability and instead will start to show signs of breaking down eventually.

Why both are equally as bad

An equipment is designed to run within a specific voltage range that is generally +/-10 percent of rated voltage; anything too high or low will shorten the lifespan of the machinery.

When your equipment starts to breakdown, it affects the entire operations of your factory or workplace. Especially if its a generator or electric motor which is giving out power supply to other equipment – it’s all the more crucial for them to be always operating normally.

Otherwise, for you to get your equipment back in tip-top condition; you may need servicing. For instance, if it’s a generator – generator rewinding might be needed to get it fixed. Likewise, a transformer or electric motor overhauling will get the respective equipment working once again.

Understanding whether you are supplying too much or little voltage always start with checking the rated voltage itself. It may be a simple task to do but it will surely help in ensuring the safety and condition of your equipment right from the very start.