wfowfo
Electrical
- Jul 8, 2005
- 97
I originally posted this question in the "motor and motor controls" forum.
"Let me see if I can explain the original concern. Suppose a recloser is looking down a distribution line. A smaller, moderately loaded line breaks off of it that is protected by this sectionalizer.
A permanent fault occurs at the end of the original line and the recloser starts going through its sequence to lockout. Each time it recloses, the sectionalizer will theoretically see an inrush and count. By the time the recloser has locked out, the sectionalizer will have also reached its "full count" and fallen open. Then it will appear there is a fault down the tap as well as the main line and cost maintenance time patrolling the tap.
The manufacturer says it will not count the inrush because, quote, "The circuitry must detect a zero crossing during the event to count. Since inrush is uni-directional until it decays, the device will not count it. A fault is alternating and will count".
Have I understood his explanation correctly as a DC offset, or have I confused it with another phenomenon?"
I have come to the conclusion from their answers that this (ie-inrush)is not DC offset. Can anyone explain to me how the phenomenon of rising above zero occurs and how it differs from DC offset?
"Let me see if I can explain the original concern. Suppose a recloser is looking down a distribution line. A smaller, moderately loaded line breaks off of it that is protected by this sectionalizer.
A permanent fault occurs at the end of the original line and the recloser starts going through its sequence to lockout. Each time it recloses, the sectionalizer will theoretically see an inrush and count. By the time the recloser has locked out, the sectionalizer will have also reached its "full count" and fallen open. Then it will appear there is a fault down the tap as well as the main line and cost maintenance time patrolling the tap.
The manufacturer says it will not count the inrush because, quote, "The circuitry must detect a zero crossing during the event to count. Since inrush is uni-directional until it decays, the device will not count it. A fault is alternating and will count".
Have I understood his explanation correctly as a DC offset, or have I confused it with another phenomenon?"
I have come to the conclusion from their answers that this (ie-inrush)is not DC offset. Can anyone explain to me how the phenomenon of rising above zero occurs and how it differs from DC offset?
