What is a generator transfer switch?
A Transfer Switch is an electrical device. When used as a diesel generator accessory, they are used to keep the mains and generator supply separate, so that only one of these can supply power to your electrical load (the items in your house and business that use electricity) at the same time.
There are two main types of transfer switch. Manual Transfer Switches and Automatic Transfer switches.
How does a generator transfer switch work? What does it do?
A generator transfer switch has three main connections, one to the load, one to the mains and one to the generator. The connection to the load remains and it switches between the load and the generator - making sure it does not connect both together.
Manual transfer switches need you to physically turn a switch or handle to change between the mains and the generator and to start the generator yourself. Automatic transfer switches change over automatically and start/stop the generator.
On the left is a manual transfer switch (note the handle) and the right an automatic transfer switch.
Why is a transfer switch panel important?
A transfer switch (either manual or automatic) is required in every country when installing a generator at premises with a mains supply. It is required by law for good reason. A transfer switch avoids:
- The mains power coming into contact with the generator, which would almost certainly burn out if this happened.
- It stops the generator from back feeding the mains when its failed, endangering the lives of electricity utility workers.
It is essential, in all circumstances, that a fool proof method of isolating the grid from your generator when the mains has failed. Never be tempted to save a few pounds and risk the lives of others. The consequences for them, for yourself and your family could be disastrous.
Back feeding the grid when it has failed is a severe risk to the life of any grid employees working on the lines, poles or transformers. Imagine the grid cut the power to your street, because a transformer needs replacing. It’s going to take them around an hour. You start your generator, which you have connected directly into your fuse board and you haven’t stripped the main breaker in the house. The power will travel back into the grid, directly to the man working on the transformer, potentially killing him.
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