Lightning arrestor short circuit rating
Lightning arrestor short circuit rating
(OP)
I'm trying to select a lightning arrestor for use in medium voltage metal enclosed interrupter switchgear (ANSI C37.20.3). A manufacturer has recommended an MOV type with EPDM package, and a short circuit rating of 15kA. The available fault current is 21kA. Is it required that the arrestor short circuit rating match or exceed the available fault current?






RE: Lightning arrestor short circuit rating
In the ABB Switchgear Manual is underlined about MO [metal-oxide surge arrester] the followings [extract]:
"Under extreme fault conditions it is possible for lighting arresters to be overloaded.
In such case e.g. a voltage rise from one level to the next, a single-phase earth fault occurs in the resistor assembly of the arrester. The pressure relief system prevents the porcelain housing from exploding. The system earth-fault current at the arrester's location must be smaller than the guaranteed current of the arrester's pressure relief device."
I think even EPDM is more elastic than porcelain the same rule it must be kept.
Best Regards
RE: Lightning arrestor short circuit rating
Your arrester should be able to handle the amount and duration of any overvoltage that results from a fault. This is the temporary overvoltage or TOV rating, usually shown charted as per unit of MCOV versus time.
RE: Lightning arrestor short circuit rating
I have to agree with stevenal as the Hubbell Power Systems company sustains:
"The pressure relief rating of porcelain arresters is valid for only the first fault event. System reclose on a failed porcelain arrester can cause fracture of the weathered porcelain housing being subjected to a second discharge of system fault current.
Polymer arresters have the advantage of being able to withstand multiple system
reclose events without exploding. Therefore, polymer arresters offer a distinct advantage over porcelain."
See:
http://
My experience is only with porcelain arresters which exploded often [BBC and ASEA] as the pressure relief current was lower with respect to shortcircuit current. But I have experience with Hubbel co. on other field and was satisfactory.
Best Regards
RE: Lightning arrestor short circuit rating
RE: Lightning arrestor short circuit rating