Current Surge AFTER breaker trips???

348 Views 3 Replies 4 Participants Last post by dmxtothemax, Jun 26, 2020

MikeDobbs

Discussion Starter · Jun 25, 2020

I shot this video while trying to diagnose a problem with my pool heat pump. Perhaps relevant to this thread is that the problem turned out to be the breaker itself. It was running very hot after 13 years in the outside electrical cabinet.

Here's my question. If you watch this video you can see that the breaker trips at about 70 amps on the meter (it's a 50 amp breaker), but immediately after it trips the current surges to about 180 amps.

This is very perplexing to me. I have two working theories.

1) It could just be a phantom reading if the meter isn't quite reading the current properly as the breaker trips

2) It could be something analogous to water hammer, whereby shutting a value suddenly causes a surge in water pressure. The problem is, this is due to the momentum of the water, and electrons has very little mass, so I don't know if they have enough momentum to create a similar effect.

If anyone has some insight into what's happening, I'd be very interested to hear. Thanks! Video link below.

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Missouri Bound

· #2 · Jun 25, 2020 (Edited)

I doubt there is such a thing as phantom amperage.
I would be interested in seeing what happens with an analog ammeter.
I would think that phenomenon is exclusive to digital meters....unless what you are experiencing is a dead short as it happens and the meter is "catching" it one the way up.

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lenaitch

· #3 · Jun 26, 2020

That looks like an induction pick-up that probably uses some kind of coil to pick up the measurement. When a magnetic field collapses, it induces current flow that has to go somewhere. I think if you used probes, either on a digital or analogue meter, you wouldn't see it.

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dmxtothemax

· #4 · Jun 26, 2020 (Edited)

This phenominin is known as "BACK EMF".
it is caused by the collapsing magnetic field
and is associatted with inductive circuits.
Under the right circumstances the back emf can be very substancial
all thou it is breif it is real,
some sensitive electronics don't always like them.

https://en.wikipedia.org/wiki/Counter-electromotive_force

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