What is a transfer switch? A transfer switch is an electrical switch, that switches back and forth a load between two different energy sources. Some transfer switches are manually operated, while others are automatic and switch over when they sense a gain or loss of power in one of the sources. Often times, an automated transfer switch is located next to a backup generator, so that the generator can temporarily provide power if utility sources fail. One example of an automated transfer switch is the Thompson transfer switch. Many reliable generator and part suppliers sell Thompson transfer switches.

There are several types of transfer switches. An open transition transfer prevents backfeed from occurring. It is also known as a break before make transfer switch, and this refers to the fact that it breaks contact with the first power source before switching to the next. A closed transition switch is also known as a break after. Most emergency systems use open transition, but some need closed transition because for some power loads, even the slightest loss of power can affect them, such as that which occurs with the open transition system. The closed system usually needs to make suer that the overlap is less than 100 milliseconds long.

A soft loading transfer is another type of transfer switch, which changes the amount of load that can be accepted by the generator. A static transfer switch, on the other hand, uses power semiconductors in order to transfer loads between two sources. There are no moving mechanical parts involved, meaning that the transfer can occur very rapidly.

One place you might find these sort of transfer switches, including the Thompson transfer switches, is in refurbished generators. Refurbished generators for sale are one type of machinery that makes use of transfer switches, as noted previously. Get more here.