copper busbar tin plating_ LV switchgears _ feeder pillar panels

[Irangi]

Hi,
1. what is the most suitable method in switchgear manufacturing either using already tin plated busbars or get tinplated after cutting and drilling before assemble?
2.If manufacture uses tinplated bus bars how can they treat drilled holes and cutting ages which got exposed ? are there any approved Sn based paints available ?
3. Are there any International standard for tinplating of copper bus bars where required testing methods are specified to assess the quality of tinplating ?
4. Are there any methods available to use in the site /field to repair /touchups discolored / pealed off areas in tinplated busbars mounted inside a panels.

Thank you
BR
Rukshika

 

[RedSnake]

I don't think they tinplate after cutting and drilling.
The tinplate is there to protect the copper from oxidation in the area where the connection between to power conducting parts are.
And the connection surface between the two parts are the flat area around the hole itself not the area "inside" the hole or the end of a bar.

/A

“Logic will get you from A to Z; imagination will get you everywhere.“
Albert Einstein

 

[che12345]

Dear Mr. Irangi (Electrical)(OP)24 Sep 21 09:25
[highlight #3465A4]" 1. what is the most suitable method in switchgear manufacturing either using already tin plated busbars or get tinplated after cutting and drilling before assemble? "[/highlight]
If you need* the (punched/drilled hole and cut edges) to be tinned, it is better to get [tin plated after cutting/bending etc. and drilling before assembly]. Note: i) that is if you need*. In practical/empirical applications, there is NO need to tin the drilled or cut edges of copper** bars ; irrespective whether used in indoor (dry) or out-door (wet) installations. ii) any oxidation on those exposed areas are minima and harmless to the contact resistance.

2.If manufacture uses tinplated bus bars how can they treat drilled holes and cutting ages which got exposed ? are there any approved Sn based paints available ?
Unless it is (explicitly stated in the specification); the manufacturers would NOT carry out any treatment on the copper** bars exposed edges. If required, spray silver paint [superficially over the edges only], NOT on the contact surfaces. Attention! check it is a [conductive] silver paint.

3. Are there any International standard for tinplating of copper bus bars where required testing methods are specified to assess the quality of tinplating ?
Yes, there are IEC and ANSI standards. Sorry, I do not have them in hand.

4. Are there any methods available to use in the site /field to repair /touchups discolored / pealed off areas in tinplated busbars mounted inside a panels.
a) If possible, dismantle the short lengths, send them for tin-plating.
b) Hot dipping or heating up the bar and apply tin on the surfaces is NOT ideal.
c) Site spray superficially with silver spray paint, though NOT ideal; but could be considered. Attention! carryout a contact resistance test with current as high as possible but not less than 100A. Compare the resistance with the equal length of undamaged tinned bar. The resistance of the repaired (coated with conductive silver paint) of same length shall be within say NOT more than 1%. This test is needed to ensure that the spray on conductive silver paint is not an added resistance film. Attention! examine the spray on silver paint [after curing] does NOT catch fire at 100 deg C.
Che Kuan Yau (Singapore)

 

[Irangi]

Thank you very much for the valuable feedback Redsnake and che1234.

***3. Are there any International standard for tinplating of copper bus bars where required testing methods are specified to assess the quality of tinplating ?
Yes, there are IEC and ANSI standards. Sorry, I do not have them in hand.

Any body can suggest the IEC or ANSI standard no ?

 

[prc]

ISO 2093 gives specifications and test methods for electro-tin plating

 

[che12345]

Dear Mr. Irangi (Electrical)
@ Mr. prc
1. Thank you Mr. prc "...ISO 2093 gives specifications and test methods for electro-tin plating ".
2. The next question is "what is the proposed tin thickness...?"
I would suggest for [INDOOR FIXED] connections, the thickness >=4um t <=8um would be adequate. Any further increase in thickness (see ISO 2093) does not serve any additional advantage/purposes, but increase in cost and plating time.
Che Kuan Yau (Singapore)

 

[che12345]

Dear Mr. Dear Mr. Irangi (Electrical)
" ...4. Are there any methods available to use in the site /field to repair /touchups discolored / pealed off areas in tinplated busbars mounted inside a panels....".
I would like to suggest the following opinion:
i) Re discolouration:
a) If the tinned surface turn [dulled], no action need to be taken.
b) If the surfaces show sign of [over-heating] or [pitting between the contact surfaces], immediate action MUST be taken! Potential of [fire] risk! Repair the surfaces, check the design (See DIN standard for detail), bolt+ nut quantity, grade and size, use of conical disc washers, proper tightening torque etc. Conduct a contact resistance test with "4-point" measuring method with current ac or dc as high as possible but NOT less than 100A. There are standard instruments (with uOhm range) on the market, or may use the car battery as a simple site test. A cell (3-4.5V) operated DMM even with 4-point method is NOT suitable.
ii)Re pealed off:
a) I have not come across. It could be due to bad plating? See ISO for detail on adhesiveness test.
It is hope that these additional information would be useful.
Che Kuan Yau (Singapore)