Register to reply

Arcing - What affects size of arc when switch is opened?

by Crazyhorse2882
Tags: affects, arcing, opened, size, switch
Share this thread:
Crazyhorse2882
#1
Nov10-13, 10:20 AM
P: 20
When an electrical circuit is opened or closed there is an arc between the terminals/buss that the switch or breaker is connecting or disconnecting and the arc is greater depending on the amount of voltage. My question is, is the arc greater when there is a resistance/load on the circuit? I'm guessing yes, but what is the effect and how could you calculate it?
Phys.Org News Partner Engineering news on Phys.org
New filter technology uses inert gas to bore holes in high-quality steel
Augmented reality helps in industrial troubleshooting
How wireless technology can dramatically improve ship safety
mfb
#2
Nov10-13, 11:03 AM
Mentor
P: 11,890
You have to consider the whole circuit to determine that.
In general, inductances (especially coils), large switching voltages and large currents will increase the amount of arcing you get.
OmCheeto
#3
Nov10-13, 12:24 PM
PF Gold
OmCheeto's Avatar
P: 1,431
Quote Quote by Crazyhorse2882 View Post
... is the arc greater when there is a resistance/load on the circuit? ...
Without a resistance/load, you wouldn't have a circuit in the first place, and therefore wouldn't have an arc at all.

Crazyhorse2882
#4
Nov10-13, 01:35 PM
P: 20
Arcing - What affects size of arc when switch is opened?

So then if a main breaker was closed outside of a building feeding equipment inside the building but their individual circuits were open then there would be no arc as that breaker closed? There would be voltage but no current and my understanding is that it will arc
OmCheeto
#5
Nov10-13, 01:50 PM
PF Gold
OmCheeto's Avatar
P: 1,431
Quote Quote by Crazyhorse2882 View Post
So then if a main breaker was closed outside of a building feeding equipment inside the building but their individual circuits were open then there would be no arc as that breaker closed?
That is correct.
There would be voltage but no current and my understanding is that it will arc
No, it will not arc.
Windadct
#6
Nov11-13, 08:09 AM
P: 564
To emphasize this point - for medium voltage switches - there are two general classes "no load disconnect" and "load disconnect" - The no load types are ideally interlocked ( often literally with locks and keys - ref Kirk Key) - with the load side circuit breaker. The Load side circuit breaker must be open - to get the key that allows the line side "no load" switch to be operated ( opened or closed).
TO feed a transformer a MV switch used on the primary is technically a load break switch (it will have an arc chute & arcing contacts- separate form the main contacts) , but only rated to interrupt the magnetizing current of the transformer it feeds - so you still see the interlocking scheme.


Register to reply

Related Discussions
How long it takes to discharge capacitor when switch is opened Introductory Physics Homework 6
Arcing in air? General Physics 2
How to eliminate arcing in a switch? Electrical Engineering 4
Size of a switch? Electrical Engineering 1
Ionizing air purifiers and arcing Chemistry 1