G
Genset
Hi,
I work for a generator manufacturer. We manufacture Automatic Transfer Switch panels for use with our generators, configured in the following way:
Mains and Generator supply are fed into an ATS panel containing interlocked (mechanically and electrically) contactors. The load side of the contactors are looped and the cables are then connected to a circuit breaker which feeds the distribution board/consumer unit. Three phase or single phase the set up is the same.
Does anybody have an opinion as to whether this is unsafe? I recently read a question (pasted below in italics) raising the issue of prospective fault current on the mains supply and that the mains contactor should be replaced with a circuit breaker.
Contactors are purely designed to switch a load (turn it on or off). They generally have a low Fault Current tolerance. Circuit Breakers are also designed to switch loads but can withstand greater Fault Currents.
For an ATS, a contactor is acceptable "on the generator side" (very low prospective fault current). The only way a contactor can be SAFELY used on the SUPPLY side is if the supply contactor is adequately protected by HRC fuses (minimum BS88), which can make this scenario prone to "nuisance trips". Therefore, the only solution is to use a circuit breaker for the supply protection (cheaper than a contactor) & to also make sure that adequate seperation between the generator supply & the incoming supply, is adequate. This is done to prevent magnetic affects from affecting the contactor under "fault" conditions.
I would appreciate your opinion on this question.
Regards,
Genset
I work for a generator manufacturer. We manufacture Automatic Transfer Switch panels for use with our generators, configured in the following way:
Mains and Generator supply are fed into an ATS panel containing interlocked (mechanically and electrically) contactors. The load side of the contactors are looped and the cables are then connected to a circuit breaker which feeds the distribution board/consumer unit. Three phase or single phase the set up is the same.
Does anybody have an opinion as to whether this is unsafe? I recently read a question (pasted below in italics) raising the issue of prospective fault current on the mains supply and that the mains contactor should be replaced with a circuit breaker.
Contactors are purely designed to switch a load (turn it on or off). They generally have a low Fault Current tolerance. Circuit Breakers are also designed to switch loads but can withstand greater Fault Currents.
For an ATS, a contactor is acceptable "on the generator side" (very low prospective fault current). The only way a contactor can be SAFELY used on the SUPPLY side is if the supply contactor is adequately protected by HRC fuses (minimum BS88), which can make this scenario prone to "nuisance trips". Therefore, the only solution is to use a circuit breaker for the supply protection (cheaper than a contactor) & to also make sure that adequate seperation between the generator supply & the incoming supply, is adequate. This is done to prevent magnetic affects from affecting the contactor under "fault" conditions.
I would appreciate your opinion on this question.
Regards,
Genset
