An ATS generates switching transients much the same way a utility does.
These transients can damage downstream equipment. A surge protector is
always recommended downstream of an ATS.
Historically, the front
end of an ATS did not need protection due to sufficient withstand ratings.
However, modern ATS employs denser microcircuitry than ever before. Critical
control boards suffer damage from transients on the input. If the generator
is located inside the facility, the emergency input probably does not need
protection. Generators located outside facility come into contact with
nearby lightning strikes that can bring a surge directly into the building.
A surge protector on the emergency feed is an important consideration.
The diagram above shows a
simple make-before-break ATS. There are other styles of transfer
switches that include bypass-isolation, expensive and not very common, and
static transfer switches, which are even more expensive and much less
common, but the same basic principles apply.
If you have any questions
or wish to learn more, feel free to call 1-800-851-1508 or email Paul Moraff
Other Topics of interest
Anatomy of a UPS