Blog posts of '2021' 'September'

Reasons Why You May Wish To Consider A Standby Generator

An emergency power source in the UK is an independent source of electrical power that can provide security and safety to important electrical systems and apparatus in the event of the mains supply failing for one reason or another. A standby power system can include batteries, a power generator, and so on, and they are there to protect life and property in the event of the mains power supply being broken. 

Places such as hospitals rely on a constant supply of power in order to provide medical support to patients and to be able to continue an operation if, for instance, the mains power supply fails in the middle of the procedure. Other places which rely on a constant supply of electrical power include scientific laboratories, computer systems, telecoms, radio and TV stations, and many more.

We also want a constant supply of electricity in our homes. This may not be a situation which is life-threatening, but it can be a nuisance if electric power goes down in the middle of cooking a meal or even just watching a programme on the TV.


More Homeowners Are Considering Installation Of A Standby Generator

This is why more and more homeowners are considering the installation of a standby generator so that everything can run as usual even if the mains power is not available. For instance, a homeowner may also be a lover of tropical fish, and these could be lost if mains power is not available for several hours and the water in the tank goes too cold. An emergency power source in the UK in the form of a standby generator can kick in almost instantly when the mains power goes down, especially if an automatic transfer switch is in operation.

Indeed, a transfer switch is a legal requirement if you have a standby generator because there could be danger to electricity supply employees endeavouring to restore power, and there is also a risk to the generator if there is no transfer switch.

Mains power can be lost for a number of reasons, often because of downed lines as a result of poor weather. However, there may also be a malfunction at a sub-station, planned downtime for repairs, or even a grid-wide failure.

Emergency backup can include batteries, and some larger buildings have a gas turbine, but this can take between five and thirty minutes to achieve full power. So, a standby diesel generator is the most common form of backup in the event of mains failure. 

Importance of an Automatic Transfer Switch

If you have a standby generator at your home so that you can still generate electricity when the power fails, then the law requires you to have a transfer switch. This is the case in every country when installing a generator at a property with a mains supply. It can either be a manual transfer switch in the UK or an automatic transfer switch. It doesn’t matter which, but you must have one or the other.

The reason is actually quite simple. When you have a transfer switch it will prevent the generator from back feeding the mains when it has gone down which would put the lives of electricity workers in danger while they are attempting to restore power. It is also good for your generator because it stops mains power from coming into contact with it, which would almost certainly burn out your generator.

One advantage of a manual transfer switch in the UK is that it is cheaper to buy and install than an automatic transfer switch. However, it means that you have to switch it over manually, obviously, which means that there will be a delay in the power supply to your home or business premises.


Somebody Needs To Be On The Premises

Not only that, but it also means that somebody needs to be on the premises at the time the mains goes down. In some instances, this may not be much of a problem, but could cause issues if you need a constant supply of power. With an automatic transfer panel, the generator will start up automatically whether you are there or not.

Automatic transfer switches come in a variety of designs, but typically a mains failure relay is fitted in an electrical enclosure, with two contactors. These are electrically and mechanically interlocked so that they cannot both be closed at the same time. The contactors need electric power in order to close.

The mechanical interlock should stop both contactors closing at the same time, but the electrical interlock provides extra protection. A normally closed contact is fitted to each contactor and when the contactor is energised, they open. If you have two contactors, A and B, the circuit to close contactor A is wired through the auxiliary of B. Therefore, when B is closed, it is not possible to energize A. The same is true for B, which is wired through the auxiliary of A. This provides the electrical interlock.

What happens is that when the mains fails, the ATS will send a signal to the generator and when it is up to full power the ATS will open the mains contactor and close the generator contactor. When the mains returns, the generator contactor is opened and the mains contactor is closed. This means that there will always be a short break in the power supply when changing over.