Blog posts tagged with 'manual transfer switch uk'

Manual Transfer Switch For Your Generator Or Automatic? Which Is Best?

One of the biggest arguments for buying a standby generator is that you will always have electricity, no matter what. So, any issues with the electricity supply will not affect you.

This is becoming more and more important in this day and age, particularly with climate change. As we have seen very recently, there have been some very large and powerful storms that have affected homes and businesses in the North-West and Scotland, and it seems that these could become more commonplace. Some homes have been without electricity for as long as two weeks.

When you have a generator as a backup to your business, you can forget about time and productivity losses, because your generator can kick in and take over while the power is down. And there can be more to it than time and productivity losses, because when there is a sudden power outage it can cause serious damage to devices and machinery when the power comes back on if there is a power surge, yet this can be avoided if there is a power backup.

You can also cut down on your electricity consumption in a business by using a generator as a backup during peak hours. Some studies have shown that you can save as much as 40% during this time slot.

A Range Of Sizes

Backup generators come in a range of different sizes, and in order to establish what you need, whether for your home or business, you will need a qualified electrician to calculate the amount of power required. The cost of a 1kW generator is only around £300: a 7kW one would be about £2,000, a 15kW one £6,000, and so on. To this, you need to add the cost of installation which can be around another £1,000.

Now we said that you will always have electricity, and this may, or may not, be true. It depends upon the type of transfer switch that you install. You can have a manual transfer switch or an automatic transfer switch.

As you might guess, if you have a manual transfer switch you have to switch over to the generator manually. That means that if you are not on the premises when the power goes down you won’t have electricity, so if you happen to be away on holiday for three or four days, you can say goodbye to the food in the freezer!

However, an automatic transfer switch will detect when the power goes down, fire up the generator, and within a few seconds the lights will be back on. The choice is yours.  

How A Manual Transfer Switch Works

It seems that more people these days are investing in a standby generator in order to provide electricity to the home or business when the mains power goes down. This happened quite a bit recently in Scotland with all the storms that we have been having. There seems to be no doubt that climate change is an issue, and that means that those storms could become more frequent. This writer is old enough to remember the Great Storm of 1987 when our home was without power for 13 days! Fortunately, we had an oil-fired Aga cooker. If we hadn’t, we would have been in serious trouble.

In addition, of course, there is the threat of a lack of gas supply coming from Russia, and this could be used as a weapon by Vladimir Putin.

So, it makes sense to many people to have a standby generator to step in when the mains power fails. But how does the generator work?

Most generators run on diesel, and they can be started either manually or automatically when the power fails. Every generator must have either a manual transfer switch or an automatic transfer switch.

If you have a manual transfer switch you need to manually turn a handle or alternative lever to switch from the mains to the generator and then start the generator by hand as well.

Required By Law

In fact, a transfer switch is required by law in every country when you install a generator at a premises that has a mains supply. This is for two main reasons, one being that it stops the mains power coming into contact with the generator when the power is restored, which would almost certainly burn out the generator.

More importantly, it prevents the generator from back feeding the mains when it has failed which could endanger the lives of the electricity utility workers.

So, you switch from mains to generator manually and then go and start the generator. When the power is restored, you would then switch off the generator and manually switch back to the mains.

While a manual transfer switch is cheaper than an automatic one, the latter does have certain advantages. Apart from anything else, it is much faster, because it automatically starts the generator and then switches to it in seconds. If you are not on the premises when the mains fails and you use a manual switch, then you are without power until somebody returns and switches over.

Manual Changeover Switch -V- Automatic. What’s The Difference?

If you have an emergency generator the good thing is that every time there is a power blackout you can start up your generator and, literally, switch the lights back on.

The way that your generator is turned on can be either manual or automatic and it can be done using a changeover switch, also known as a transfer switch. In fact, it is a legal requirement that if you have a standby generator, you have to have a changeover switch.

This is for two main reasons. It separates the power from the two different sources. You can either have power from the mains or you can have power from the generator, but not both, at the same time.

If you did not have a changeover switch and you started your generator and then the mains came back on again while the generator was running it would almost certainly burn your generator out. The other way around, it prevents the generator feeding power back into the mains when electricity workers are trying to restore the power, which could endanger their lives.

What’s The Difference?

So, what is the difference between a manual changeover switch and an automatic one? Well. think of it as of the gearbox in your car. It can either be manual or automatic. If you have a manual gearbox, every time you want to change gear you have to depress the clutch, shift the gear lever, and let the clutch out again. If you have an automatic gearbox, it does all that for you.

A manual changeover switch means that you have to switch over by hand. You also have to start the generator, which is probably in the garden, and it could be pouring with rain! In fact, it very likely would be, because the power often goes down as the result of a storm.

An automatic changeover switch detects that the mains power has gone down, switches over, and starts the generator automatically.

You are far better off with an automatic changeover switch because there is no time delay. When the power goes down you will be back up and running in seconds. You don’t get wet in the pouring rain. It also works when you are away from home. If nobody is at home and you need the power on and have a manual switch, that power is going to stay off until you return.

There is only one advantage to having a manual switch and that is that it is cheaper to purchase. That aside, there is no contest.

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.