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

  • Thread starter Crazyhorse2882
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In summary, an electrical circuit is opened or closed, and 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.
  • #1
Crazyhorse2882
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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?
 
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  • #2
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.
 
  • #3
Crazyhorse2882 said:
... 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.
 
  • #4
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
 
  • #5
Crazyhorse2882 said:
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.
 
  • #6
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.
 

1. What is arcing?

Arcing is an electrical phenomenon where an electric current jumps or travels through the air between two conductive materials, creating a bright spark or flash of light.

2. How does arcing occur?

Arcing occurs when there is a sudden break in an electrical circuit, causing the current to jump across the gap between two conductive materials, such as when a switch is opened.

3. What factors affect the size of an arc when a switch is opened?

The size of an arc when a switch is opened can be affected by several factors, including the voltage of the circuit, the type of switch being used, the distance between the conductive materials, and the presence of any insulating materials.

4. Why does the size of an arc matter?

The size of an arc can have important implications for safety and the proper functioning of electrical equipment. A larger arc can produce more heat and potentially cause damage to the surrounding materials, while a smaller arc may not be able to sustain the necessary current for the circuit to function properly.

5. How can the size of an arc be controlled?

The size of an arc when a switch is opened can be controlled by using appropriate materials and design for the electrical circuit, such as insulating materials to prevent the current from jumping. Additionally, proper maintenance and regular inspections can help identify and address any potential hazards or issues that may affect the size of an arc.

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