Switch / Harmonics
Switch / Harmonics
(OP)
Hello,
I have a spec that calls for a 600A, 5kV 3P load break switch (we usually use S&C alduti or miniputer).
The difference this time being the spec says the switch must be capable of making and interrupting its full rating including Harmonics...which are expected to be 30% current and 10% voltage...
I am contacting S&C to see if their switch is capable... however, I have not dealt with this before..what should be my concerns? 30% seems very high....is this typical?
Regards,
TULUM
I have a spec that calls for a 600A, 5kV 3P load break switch (we usually use S&C alduti or miniputer).
The difference this time being the spec says the switch must be capable of making and interrupting its full rating including Harmonics...which are expected to be 30% current and 10% voltage...
I am contacting S&C to see if their switch is capable... however, I have not dealt with this before..what should be my concerns? 30% seems very high....is this typical?
Regards,
TULUM






RE: Switch / Harmonics
Thirty percent current distorsion is not much at all. But 10 percent voltage is a bit high. I do not really see how that could make the job tougher for the breaker. A marginally higher crest voltage, perhaps. But definitely within normal voltage tolerances.
My guess is that a consultant put that in to make life more interesting...
Gunnar Englund
www.gke.org
RE: Switch / Harmonics
Sounds like someone trying to cover every possible issue wrote your spec.
RE: Switch / Harmonics
Anyone know of a good read on the subject?
Regards,
TULUM
RE: Switch / Harmonics
I checked in the IEEE 1247-1998 Standard for interrupter switches regarding the harmonic switching capability . Under usual conditions the standard states "The harmonic content of the rated switching current shall be <10% and should cause no extraneous current zeros". Being required to break larger harmonic currents above 1000V is classified as 'unusual duty' and is not covered under any specific standard that I know of...
Also, S&C has replied that "S&C has no recorded test data on harmonic switching data, in Canada or the USA for either the Alduti-rupter or Minirupter" .
Eventhough the harmonic currents are small and the switch is going to be underloaded I am suggesting that we take exception to this requirement anyways... stating the above.
Regards,