Ka-boom

[ElectroChem]

Callout to a farm today, motor won't go. This is what greets me when I open up the control box. Lightning storm yesterday, seems the poor relay didn't appreciate the jolt. Anyone care to share their pics of utterly destroyed bits and pieces?

 

[Paul.M]

The above thread is from our Trainee friend ElectroChem from "down under". Thought it may be a good thread in the General section, ok it is from 2 months ago but still a good one.

 

[NickD]

Callout to a farm today, motor won't go. This is what greets me when I open up the control box. Lightning storm yesterday, seems the poor relay didn't appreciate the jolt. Anyone care to share their pics of utterly destroyed bits and pieces?

I see the neutral is burnt out...why is it always the neutral, eh?

 

[Knobhead]

I see the neutral is burnt out...why is it always the neutral, eh?

Quite simple, you don’t tighten them properly.

 

[Jonspark]

I see the neutral is burnt out...why is it always the neutral, eh?

Aliens

 

[Paul.M]

I see the neutral is burnt out...why is it always the neutral, eh?

Quite simple, you don’t tighten them properly.

Aliens

It did get hit by Lightning lol

 

[ElectroChem]

Yeah but the lightning was aiming for the neutral, everything else was just collateral damage.

 

[davesparks]

Quite simple, you don’t tighten them properly.

You obviously didn't read the very informative post the other day about why neutral connections burn out!
It was clearly explained the flow of voltage after the load coupled with the current passing through the load opposing itself in the third harmonic causing a greater localised heating effect, I believe this is very similar to the phenomenon which can be witnessed when you attempt to operate a flux capacitor with insufficient gigawatts in a mk2 delorean!

Terminals burning due to loose connections? Wherever did you get that crazy idea from?

 

[VoltzElectrical]

You obviously didn't read the very informative post the other day about why neutral connections burn out!
It was clearly explained the flow of voltage after the load coupled with the current passing through the load opposing itself in the third harmonic causing a greater localised heating effect, I believe this is very similar to the phenomenon which can be witnessed when you attempt to operate a flux capacitor with insufficient gigawatts in a mk2 delorean!

Terminals burning due to loose connections? Wherever did you get that crazy idea from?

Back to the future has just started on the telly. Weird timing!

 

[telectrix]

did it start tomorrow?

 

[GMES]

I have some pics on my other laptop with similar pictures I will try to remember to get them Monday and post them up.

 

[Knobhead]

On the subject of lightning strikes, my local received a direct hit while I was in there. It was amazing, all the sockets, light fittings, etc exploded. The strike was to the aerial, where the cable ran down the roof all the slates were blown off. As for the various televisions, they didn’t fair to well.
I wasn’t bothered, I was on hand pulled ale.

It’s not an experience I want to repeat!

Sanky would know the pub, he’s driven past it many times on the A38.

 

[Darkwood]

On the subject of lightning strikes, my local received a direct hit while I was in there. It was amazing, all the sockets, light fittings, etc exploded. The strike was to the aerial, where the cable ran down the roof all the slates were blown off. As for the various televisions, they didn’t fair to well.
I wasn’t bothered, I was on hand pulled ale.

It’s not an experience I want to repeat!

Sanky would know the pub, he’s driven past it many times on the A38.

Sounds like it made you spill your beer!!!!!

 

[Besoeker]

Here's one.........

 

[Knobhead]

What voltage? They look like 3.3KV fuses but the wiring doesn’t. Interesting how you can see the flashover points on the fuses. Is the white mark across the back plane tracking?

I’ve not seen anything like that for many years, nothing to do with lightning but inductive discharge when a motor stopped.
The motor had been uprated three times as I can remember, pity the draw out starter hadn’t. The fuses had gone up from 150A to 300A, obviously the fuse diameter was bigger making the gap between them far to small.
Intermittently when the motor stopped the back EMF would cause flashover taking out the 600A busbar riser fuses.
I wasn’t based on this plant but got lumbered with finding a cure. I fitted insulating shields between the fuses and everything was fine.
It ran like that for a couple of years and then the problem started again? Some pillock had replaced the nylon nuts and setscrews with brass! To make it even better they’d cut the setscrews with pliers leaving a nice point aimed directly at the adjacent fuse. It was just like a spark gap used for MV over voltage protection.

Our plants took several direct strikes but they never did any damage, the building acting as a Faraday cage.

 

[Besoeker]

What voltage? They look like 3.3KV fuses but the wiring doesn’t. Interesting how you can see the flashover points on the fuses. Is the white mark across the back plane tracking?

I’ve not seen anything like that for many years, nothing to do with lightning but inductive discharge when a motor stopped.
The motor had been uprated three times as I can remember, pity the draw out starter hadn’t. The fuses had gone up from 150A to 300A, obviously the fuse diameter was bigger making the gap between them far to small.
Intermittently when the motor stopped the back EMF would cause flashover taking out the 600A busbar riser fuses.
I wasn’t based on this plant but got lumbered with finding a cure. I fitted insulating shields between the fuses and everything was fine.
It ran like that for a couple of years and then the problem started again? Some pillock had replaced the nylon nuts and setscrews with brass! To make it even better they’d cut the setscrews with pliers leaving a nice point aimed directly at the adjacent fuse. It was just like a spark gap used for MV over voltage protection.

Our plants took several direct strikes but they never did any damage, the building acting as a Faraday cage.

The fuses are 3.6kV and so is the wiring. It's part of the speed control system for a 3.3kV slip ring induction motor. A transformer in the adjacent panel, also part of the speed control system smoked and the hence the ensuing damage. The white mark is where somebody wiped the back panel. Parts were changed as required and it all cleaned up rather nicely.

 

[Besoeker]

Here's another nice mess.

We don't what happened. The kit had been stored in an unheated room in the jungle in West Africa for about six years. It is, or was a 315kW AFE VFD. It comprises two panels split to make shipping easier. We suspect that the power connections between the two were not done up correctly leading to arcing/overheating. But who knows? Given the history, it could have been full of vermin or snakes or bees nests....

We were asked to bid for a replacement unit but that was a year or so ago. Nothing since.

 

[Knobhead]

To quote Clarkson “it’ll buff out”.