bison logo

Whether the voltage regulator (AVR) is damaged?

AVR, a solid-state device, regulates generator voltage & adjusts with load/temperature changes, part of the alternator’s excitation system.

Table of Contents

How can we tell whether the voltage regulator is damaged?

The AVR could be destroyed by anything inside, such as a broken component, or external, such as a lightning-caused short-term transient voltage spike on the power line. There are certain conditions on behalf of that we get to know whether the voltage regulator is damaged or not.


“Damage” is an inclusive phrase for “It Really doesn’t Function Anymore”. The AVR (Automatic Voltage Regulator) might be damaged inside, such as a faulty component, or externally, such as a brief voltage fluctuations spike (short-term voltage surge) on the power cable produced by lighting, or even works on the exterior power lines next to the building. The origin of the external-to-the-AVR-Box damage may even be a reverse voltage surge from of the elevator motor, though the chances of that happening are extremely remote.

The Automatic Voltage Regulator is an electrical device. As a result, it is prone to damage from power line transient voltage spikes. Yes, it is designed to reduce voltage spikes on the power line, however the voltage spikes that it is designed to rectify are relatively brief. Lightning strikes or outside work on electrical wires can create significantly shorter voltage spikes.

Voltage Level Protection

If the voltage on the incoming utility power is too low for proper elevator operation, the AVR boosts the voltage to normal levels. The AVR reduces the voltage to normal if it reaches too high for safe elevator operation.


Two Stages of Protection

The AVR protects the elevator against alternating current voltage fluctuations. To protect the AVR from high-speed transient voltage surges caused by close lightning strikes, a Surge Protective Device (SPD) or a Transient Voltage Surge Suppressor (TVSS) should be put in the power line between the AVR and the incoming utility electricity.

An SPD or TVSS does not control voltage; rather, it protects against short-term voltage spikes. It can, however, be harmed by repeated transient voltage surges. When compared to the cost of replacing the AVR, a surge protector is inexpensive. You should consider replacing the surge protector when repairing the AVR.

Transient Voltages

Lightning-induced transient voltages are extremely quick, and the AVR is incapable of dealing with such fast transient voltages. Keep in mind that the AVR is an electronic device that might be destroyed by lightning.

How to judge whether the regulator is damaged?

The following are the generator AVR failure symptoms:

Power transitions that is unexpected

If the demand on the generator quickly changes, AVR is likely to suffer shock. The AVR would not regulate the voltage if the power drawn suddenly increases.


Furthermore, when the generator is overworked, its frequency falls, resulting in a drop in voltage. The voltage regulator will strive to maintain a constant voltage to compensate for the voltage drop. As a result, it is prone to injury.

Failure of a circuit breaker

When a short circuit occurs due to a fault. The generator and voltage regulator will be damaged if the relays do not operate the breaker.

Variable generator engine speed

When the generator speed rapidly increases, so does the voltage produced. The sudden voltage increase will destroy AVR.

How to test an AVR with multi-meter to measure whether the voltage regulator is damaged?

To test the generator AVR with a multi-meter, follow these procedures.

  • Select AC voltage on the Multi-meter.
  • Connect the L and N pins to the red and black probes, respectively.
  • To check the output. Set the Multi-meter to DC mode.
  • Connect the black probe’s negative pin to the red probe’s positive pin.
  • A 220V AC input requires an output voltage of 90-100V DC.
  • If you don’t have a multi-meter, you can use a test bulb to see if the AVR is working.

BISON diesel generator AVR

BISON Generator is a company specializing in the production of diesel generators and accessories. Designed to ensure that the generator’s voltage output remains stable even with fluctuating loads, helping to prevent equipment damage and ensuring it is always available when needed. BISON Generator’s focus on quality and reliability has built a solid reputation in the industry, attracting customers around the world who rely on its products for critical power applications. Whether you want to power a small home or a large industrial complex, BISON Generator has the expertise and technology to provide the right solution for your needs.

Generator AVR FAQ

To put the generator’s AVR to the test

  • After adjusting the Multi-meter knob to AC, connect the meter probe to the input pins.
  • Let’s have a look at the results now.
  • Connect the output pins to the Multi-meter Knob and set it to DC.

AVR failure can be caused by the following factors:

  • Variable generator speed
  • Power fluctuation
  • Overload
  • Short Circuit

To evaluate the AVR

  • Plug to the power source and examine the reading with a multi-meter.
  • Attach the load and set the multi-meter to DC to measure the voltage.
  • The AVR is adequate if the load is operating and the meter is reading.

If the AVR in your generator fails, the generator will lose excitation. Because of the lack of excitation, the voltage at the generator drops rapidly, leading the generator to shut down on an under voltage fault.

A defective voltage regulator can cause the alternator to undercharge or overload the battery of the vehicle. Undercharging can result in a discharged (dead) battery, whilst overcharging can cause internal battery damage.

We conclude that an Automatic Voltage Regulator is a vital generating component. Without it, the generator is prone to power interruptions and sparks. Without the AVR, the voltage would not be stable. The performance of the generator may degrade as a result of this instability.

What are the factors to consider regarding voltage regulator?

Things to consider are; Voltage regulator damage symptoms, Voltage regulator failure signs, Voltage regulator troubleshooting, Voltage regulator testing, Voltage regulator diagnosis, Voltage regulator repair, Voltage regulator replacement, Voltage regulator problems, Voltage regulator failure modes, Voltage regulator failure causes, Voltage regulator test procedure, Voltage regulator fault diagnosis, Voltage regulator malfunction symptoms and Voltage regulator testing and repair.

contact us

Please complete our contact form and we will soon get back to you with expert advice.


Get in touch to speak with our experts!

enquire today

Speak with our sales manager today for additional information or an obligation-free quote.