Panel Board Selection

It looks like big workshop's power build project. My dearest apology but it must be paid to design and consultancy. I have done many projects such as this but sorry could not give you any advice unless...

Why don't you just publish your fees?

I was under the impression that advertising services is regarded as spam.

I ain't advertising my services to you. I have paid US dollars 2200 for a short course myself justo last year to prepare for such tasks to the best service. It is just a different way of expressing disagreement. A disagreement to do homework like that. In actual work projects one would be liable for any wrong ideas, calculation, high spends, etc. Asking such questions like a panel or not showing me nothing but a "JOKE". That was my reply to a JOKE. Sorry, I am not interested in charging fees but a good design for such work must have a separate panel. However, the panel or Sub Main Panel or distribution board must be near the workshop.

Does that amount guarantee best service?

Just as getting education in a standard, accredited and recognized institute acknowledges by degree, similarly one strives for the best training all along in life. The following exam and training qualifies me in Abu Dhabi, United Arabs Emirates beside the American degree. God is all knowing and the fees for this exam has been deducted of my salary where as the company should have paid for it as promised. The matter had gone to court and I am sorry to say that arrow hits its target i.e the Arab court did not make the Arab's company to pay me for these huge fees. Anyway, just a food of thought, nothing more...Hahahahaha...

A MCC panel for a workshop would be unusual but there's nothing wrong with the idea.

Just remember as with any workshop things will alter so a central panel could become a problem.

Consult a qualified electrical designer locally - one that can visit the site and ask detailed questions.

Plasma cutting and Rolling machines could be fed directly from MSB vis isolators near the machines but for lights & sockets you may use a sub-DB of suitably rated CB/fuses.

Having a 3 phase Main Distribution Board with 3 Phase Mains Incomer (suit Generator rating), 3 phase outgoing MCCBs for each large load such as rolling mill and Plasma and one section of MDB as multiway 3 P +N distribution for small power outlets and lights shall do your job. But take care of following before you invest in Power Generation and Evacuation System:

1. Ensure that Diesel engine can take the starting load of Mill (I do not know whether this is small mill to draw Cu or similar soft metal of steel).

2. Evaluate to ensure that 3 phase alternator is sufficiently over-sized to cater for Harmonics of mill and plasma, and poor power factor expected as the rolling mill build up speed.

3. Carefully choose the flood lights to avoid poor power factor and resultant effect of alternator.

4. Select MCCBs with short circuit trip unit adjustable in range of 2 to 5 times full load current of 3 phase alternator. Small DG sets have limited fault feeding capacity (3 times of FL Current for 3 Secs or 10 Secs (10 secs if with pmg pilot exciter or series boost capacitors). Similarly select proper characteristic of MCBs. (say 'B', 3 to 5 x I or 'Z' 2 -3 x I characteristics. 'Z' will also take care of clearing faults in case of semiconductors type load).

If you can improve your power factor to 1, you can save approximately 2% fuel of DG Set which is lot for a continuous base load set.

Sorry I shall not be able to devote more time in case of any clarification - as too busy with work at hand.

If in doubt hire a consultant, pass on to him this note to work out details for you.

best of luck

A few more details please

Is this going to be a permanent installation or only temporary? Makes a difference in some of the materials used.

Is there a qualified industrial electrician anywhere near?? They should know the required codes and can likely size everything for you.

It's a temporary fabrication shop(2 years at max.). We have 3 plazma cutting machines each of 37 KW, 2 rolling machines each of 50 KW and a blasting machine of 250 KW.

For machineries, I think the generator with the rating of 3 times the combined load would suffice for the starting current. That's also mentioned in the machine manuals. I can size the current and OCPDs. I only wondered whether to put all the loads in one panel board or separate.

I have two options in my mind:

a) connect all the machineries to the generator via diconnect switches and the remaining load(lighting and power sockets)via panel board.

b) connect all the load through a single panel and use MCCBs of suitable sizez for the machineries and a sub-panel of ligthing etc.

Which option you think would be better?

I see the load requirements changes...

a) Isolators (Switches) for machinery and separate Distribution board for lighting and power would work. That means you would have one MDB and ...

b) Just one MDB would work too

c) What I would ALSO suggest:

i) Have a sketch uploaded showing the locations of each and every if possible

ii) from the sketch, one could determine the location of the genset.

iii) From there one could determine really if you would need one or even more panels.

Note: protecting the circuits the best way possible and affording the COSTS

Well, temporary, it is all really going to come down to the cost then. I am not up to speed with all the different costs anymore, so to me, your best bet would be to get a quote from qualified electrician(s) doing it both ways. But, in order to get some accurate costs, you should have the layout of the shop sketched up (with some basic dimensions as to machine locations) as it appears that most of your money will likely be spent on cabling.

As for a central panel, and being temporary, unless you think the panel will be reused or can be sold to recoup some of you costs later, a plain splitter panel and disconnects are easier to dispose of (resell or reuse) as they are more flexible.

Being a licensed electrician, temporary is classified as 90 days or less. Two years is considered permanent. I have had first hand experience with "temporary" work winding up to 5 years or more. If I were to do this electrical installation, there would not be any price for "temporary".

It is nice to hear you describing temp and permanent. Having said many things above, on one of another serious note, I have seen it in exhibition on display, a portable industrial distribution board. It is as easy portable and has all the built-in functions. It has all the industrial sockets etc. It comes ready or custom too. Made in Germany. I don't get to keep all these free soft or hard copy catalog. Here is another tip.