Camera and Frame Grabber got damage to Surge 1

[Shivam Maury]

Hello Everyone,

There is a situation where in we have mounted camera on the label Rewinder machine. But in machine input supply Earthing and Neutral got swappeed (at input supply side).

and during that we were testing MCB & RCCB but surge went to costly camera and framegrabber (which was connected to PC) damaged.

How to protect whole circuit if Neutral and earth is swapped.

Also attaching hand skteched drawing, please help in that case.

 

[LittleInch]

Nothing attached

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

 

[waross]

Are you sure that the damage was not done by an open neutral?
When a hot and neutral are switched, on a center tapped circuit, (for example 120/240 Volts) the opposite line voltage jumps to double.
There are small protection devices available that will not turn on if the voltage is not within limits.
The most common of such devices are intended for the protection of residential refrigerators and incorporate a time delay of a few minutes when initially energized.
This will also protect against an open neutral.
Amazon


--------------------
Ohm's law
Not just a good idea;
It's the LAW!

 

[IRstuff]

https://www.fluke.com/en-us/learn/b... neutral and,neutral and ground are switched.

Power problems happen often
> We had a custom power wired for us by an EMI testing house who, apparently, didn't check their work. We connected our system and fried half of it. Took us months to troubleshoot and replace all the damaged boards and components.

You must adhere to Reagan's admonition, "Trust, but VERIFY"

TTFN (ta ta for now)
I can do absolutely anything. I'm an expert!

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[che12345]

Mr. Shivam Maury (Electrical)(OP)17 Jul 23 07:24
[COLOR=]"....There is a situation where in we have mounted camera on the label Rewinder machine. #1. But in machine input supply Earthing and Neutral got swappeed (at input supply side)..... #2. and during that we were testing MCB & RCCB but surge went to costly camera and framegrabber (which was connected to PC) damaged....#3. How to protect whole circuit if Neutral and earth is swapped"[/color].
I assumed the system is 1-phase with [Line], [Earthed Neutral] and [Earth]; three conductors.
1. When the system is on load, L-PE > L-N (say about 1V difference, the exact value is dependent on the load). If L-N > L-PE (N and PE is swapped).
2. Use MOV to protect the over-voltage surge.
3. check the RCCB input should be connected to L and N only. PE must NOT be connected to the RCCB.
3.1. With RCCB input L and N:
a) when the RCCB output L to load L , N to load N; it will work fine.
3.2. With RCCB input L and PE instead of N (attention: wrong connection!)
a) when the RCCB output L to load L , PE to load N; it will also work fine. (Attention, RCCB unable to detect this mistake !).
Che Kuan Yau (Singapore)

 

[waross]

a) when the RCCB output L to load L , PE to load N; it will also work fine. (Attention, RCCB unable to detect this mistake !).
Che Kuan Yau (Singapore)

????

--------------------
Ohm's law
Not just a good idea;
It's the LAW!

 

[che12345]

@ Mr. waross (Electrical)19 Jul 23 18:45
".... when the RCCB output L to load L , PE to load N; it will also work fine. (Attention, RCCB unable to detect this mistake !).....????...".
I analyze it as following. All advice are welcome.
1. with correct connection:
RCCB input L and N, output L to load L and N to load N. PE connected to the load conductive frame.
2. with WRONG connection:
RCCB input L and PE , output L to load L and PE to load N. Line N connected to the load conductive frame.
2.1. when there is NO insulation break-down
a) the load works fine, RCCB remained closed,
b) any person in contact with the load frame (may not?) feel the low current flowing through the body. Reason being the voltage between N and PE is very low, say < 1V.
2.2. when there IS an insulation break-down, either load L or N to the frame.
a) when insulation breaks down (assuming a dead short) is between load L and frame. The RCCB trips. Reason being the difference between L and PE exceeded, say (15-30mA),
b) when insulation breaks down (assuming a dead short) is between load N and frame. The RCCB trips. Reason being the difference L and PE exceeded, say (15-30mA),
3. Conclusion: RCCB unable to detect this mistake ! .
Che Kuan Yau (Singapore)

 

[waross]

The RCCB works by comparing the outgoing current with the returning current, or vice versa.
If the currents are different by more than the RCCB rating, the RCCB assumes that the current difference is returning through an inadvertent ground connection and the RCCB trips.

a) when the RCCB output L to load L , PE to load N; it will also work fine. (Attention, RCCB unable to detect this mistake !).
Che Kuan Yau (Singapore)

Some or all of the current may return on the PE conductor and the RCCB will trip.


--------------------
Ohm's law
Not just a good idea;
It's the LAW!

 

[che12345]

@ Mr. waross (Electrical)20 Jul 23 02:31
Quote:
a) when the RCCB output L to load L , PE to load N; it will also work fine. (Attention, RCCB unable to detect this mistake !)....Che Kuan Yau
Some or all of the current may return on the PE conductor and the RCCB will trip.... Mr. waross

I am of the opinion that when the load is healthy, [i.e. (NO insulation break-down) between L or N to the frame], ALL the current must return on the PE conductor. The residual current between L and PE would be zero. The RCCB will NOT trip. Reason being when there is no insulation break-down, the leakage current through the frame to the N is expected to be very low (i.e. lower than the RCCB setting).
Che Kuan Yau (Singapore)