A change over switch is a device that is used to turn off one power source and then turn on another. Essentially, it is intended to turn on a more convenient power supply to the load. Because it turns on power to the load, care must be taken when selecting the type of change over switch. Size and arcing control are also factors in the selection.

A good switch should have contacts that are designed to limit arc formation by having no contact bounce and contacts made of good conductive, corrosion resistant, and wear resistant materials.

A good changeover switch must have adequate insulation and be constructed and located in such a way that it does not cause any problems.

constitute a potential risk.

A good change over switch should also have tight contacts to limit or eliminate partial contacts at the contact point. The partial contact causes overheating of the components and may result in a fire.

1.2     Aims and Objectives

Because of the inconsistency of power supply, there is an increasing need for an alternative source of power supply. This has resulted in significant capital investment in order to reduce power outages and ensure consistent power supply for our industries, hospitals, and homes. The use of a standby generator set can solve the problem of power outages.

According to Tony Rudk Inn, an engineering author, in his book “Upgraded signal source with improved performance and reliability,” the cost and depreciation associated with breakdown vary from application to application, and in some cases, the user has little choice but to ensure that a stand-by unit is available to take over in the event that the primary system fails.

If some of these major

If businesses do not plan for a backup power source, frustration can set in, leading to the closure of the business and the layoff of employees. In addition, if a hospital is undergoing a surgical procedure and the power supply suddenly goes out, the patient may lose his life as a result of the power outage.

Furthermore, if the President of the country is making a nationwide broadcast and there is a power outage in the transmitting station, it will be interpreted as an attempt to sabotage the government ruling and some people will be forced to go for it.
There is a justifiable correlation between the rate at which more sophisticated electrical/electronic gadgets are procured and installed in our homes, hospitals, and business premises.

In the event of a power outage, there is a need for a faster and more reliable changeover system.

In light of these considerations, the goal of this project is to design and build a functional automatic change-over switch with a phase selector circuit that switches the load from the National Electric Power Authority (NEPA) to a generator when power is restored. In addition, if any of the NEPA phases carrying the load fails, the change-over switch will be switched to the alternative phase.


The automatic switch is designed to perform the following automatic actions.

To turn on the generator

To switch power to the generator

To return to NEPA,

To replace the generator

To switch to an alternate phase in the event of a phase failure.

The automatic changeover unit can be used in either a single or three-phase system. The automatic changeover switch offers the following benefits.

i. It minimizes damage to lives/equipment since it has its own monitoring system and its switching requires no human contact with the switch, thus eliminating human error.

ii. It reduces its change-over timing to the minimum due to its fast response to power outage.

iii. It maintains high quality of service through its fast and prompt response

iv. It avoids and reduces

Since the generator is turned off as soon as the NEPA supply is restored, fuel consumption has increased.

Furthermore, the size and capacity of the Unit will be determined by the load. The unit is also portable, easy to install, convenient, and safe.


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