Another One For The Big Boys.......

[il78]

More help needed........

I need a switched fuse isolator (metal) rated at 80A or 100A, the problem is it need to be physically small.......

Bought a MEM excel range, got delivered this pm and the thing is massive and cant figure for the life of me another make which will be smaller.

Its to isolate an auto change over switch (job has changed from original install).....the standby board use to cover 2x 32A rings covered by a 63A MCB from the main board...now its covering 4x 32A rings (and could exceed, its ok at the moment but knowing my luck)...

So the 63A MCB is being changed for a 100A single pole MEM isolator (18mm) and then into a "switched fused isolator" to protect from over-current.......

Without going into too much detail with the above and not being able to go online tonight (laptop left in work & now sitting in a net cafe) i'm in need of some help if I cant find another make......the size I'm looking for is about the size of a 4 way board.....

Thanks in advance......and i'll buy ya's a pint, if I ever see ya's......

(Sorry if its all a bit vague)

 

[il78]

Just found something that will work

Think of anything better, let us know.......

That was a scary case of Ian's rear end twitching for a job to start tomorrow..........I can sleep tonight......

 

[Big_Spark]

Ian, instead of a 100A Isolator, why not get a small enclosure and DIN rail mount a small footprint MCCB with a 80A rating??

If you want to keep the Isolator, which is not really needed, then why not simply use an enclosure that will house the 100A Isolator and a 80A MCB?

Personally I favour the MCCB path as these are tweakable and you can adapt it to suit the particulars of the installation.

Merlin Gerin make some great small footprint gear in the NS range.

However I am curious about how this setup is achieved. Normal configuration would be via a Switch Fuse after the head, this would feed into the ACR which would share the input with your standby supply, whether Generator or UPS system..or CHP for that matter, this would then have a single output that would feed into the Main Panel of the Installation.

This seems like a VERY small supply to have an ACR in circuit, and I am curious as to why the supply is so small, as one of this size could be better served by a UPS system with a standard configuration?

 

[il78]

Cheers for reply......

The MCCB thing I did think about, but its needed ASAP (tomorrow)......my head has been up my a**s all day with other things and my head went west when I seen the size of the MEM isolator......

The ACU needs to be isolated under maintainence conditions (other company), hence the switch. I'm also very limited on space as there is non available as the client shares there offices with other companies.....UPS was considered first of all but the location was not suitable (hot area, boiler house)

The ACU will cover a selected number of circuits only (PC's really for a big computer software company)....

The job was originally done ages ago, but a newer generator has been supplied, so upgrading has taken place.....

 

[Big_Spark]

Ian, this got me intrigued so I have done a little digging, the overload protection only need be on the output side of the ACR, however if you want to do this on the Input side as well, why not use a small enclosure and mount in it a BS88 or BS1361 HRC fuse holder?

Try this for a thought?

These Wylex units arte about 120mm wide and about 250mm high (5" x 8")

You need to order the fuse for what you want as they do not come supplied.

 

[il78]

Got time to tell you more now.....

Currently

16mm cables used
63A single phase supply from 36way 3 phase board (200A) into manual change-over switch.
Supply from generator into change-over switch (63A 230V inlet)
Supply out of change-over into 4 way single phase board supplying 2x 32A ringmains (all PC's).

Generator is around 20kVA pussing out 50-55Amp.......

Proposed New Install

25mm cables to be used
Generator will be a 30kVA pussing out 90-95Amp
63A inlet to be upgraded to a 125A
Manual change-over to become an automatic
4x 32A ringmains to be covered (all PC's)

Problem I had was that the supply from the 3phase board was protected by a 63A MCB (this was ok with 2x ringmains) but now 4x ringmains are covered.....I know this might not cause a problem now, but they are always changing PC's around, adding etc....
MEM sheild 2 gear used and cant get a 80/100A MCB single pole, so used a 100A single pole (18mm) isolator, this then leaves the cables not protected from over-current, hence the fused isolator....it needed to be physically small as limited space is available as shared with other companies within the building......The other problem is that they cant loose power at any time......

There where other ways of doing the job and thinking now, I would of done different, but this is the 1st job I've ever weighed up like this (generators / change-overs etc). Its one of those jobs you need to see, if ya' know what I mean........

The overall job has been going on for about 8 months (other various things included), and yesterday was a bit of a nightmare.......

The only good thing about it is that I've actually enjoyed doing it and gained that little bit more experience

Now I hope that the engineers working there dont screw up

Just re-read you post on the sw fused isolator after the ACU....is getting me thinking again.........

 

[Big_Spark]

Ian, I'll do a little diagram for you and post it here if I can, or e-mail it to you.

Further, The 30KvA, is it single phase or 3 phase?

If it is single phase then the output will actually potentially be 130A (30K/230 = 130)

The 20KvA should be capable of providing 86A if single phase.

Also, a word of caution, It is illadvised to run computers straight from a generator, the output can play havoc with them. It is always wiser to run the generator supply via a UPS system.

If the 30KvA has not been bought and installed yet, I may have a solution for you which will solve all your problems in one go, and be able to be expanded for future upgrades.

 

[il78]

Single phase generator made to order......(iro £19000)

My concerns about the output rating were made, but the guy who made it insists that it will only push out 90-95Amps.....this will get checked and extras installed if the case....

The computers have UPS's next to them 3-5kVA just in case and on change over, 30 second delay on startup.......



With regards to the generator BS7671 states that the standby installation will be treated as a TT system....so 300mA RCBO's are to be installed, got a few doubts about this.....

This beer bill is getting bigger.........

 

[Big_Spark]

Single phase generator made to order......(iro £19000)


With regards to the generator BS7671 states that the standby installation will be treated as a TT system....so 300mA RCBO's are to be installed, got a few doubts about this.....

This beer bill is getting bigger.........

I think Dick Turpin has been in action again!! £19K, I could buy a cheaper 30KvA than that! I hope it includes install.

Regarding the TT...rubbish. The Alternator will be centre tapped, and this centre tap will be Earth and Neutral, Yes the Generator will require an Earth rod, maybe two depending on the location, but it can be treated as a TN-S. (This dig is not a poke at you )

The Generator should have it's output protected by an RCD though regardless.

Ian, I have seen standby units connected to the Lightning protection system to provide an Earth path, I do not recommend this as the strike could take out the Generator and the UPS/IT gear downwind of it.

 

[Big_Spark]

Ian, send me a quick email



I have a basic setup picture that you may find useful, but I cannot access any webspace at the moment to host it.

 

[il78]

did put an email address up, but its gone, I aint at home and cant send emails......il1978 at msn . com (ya know what i mean) i'll then send you my home email......

 

[il78]

The price includes everything and maintainence packages etc.....

 

[SPARKED OUT]

is mem gear any good

 

[BR]

Yes, MEM is considered a reasonably good make when it comes to electrical accessories however like MK, are expensive for use in domestic installations (sockets switches etc) MEM are aimed more at the industrial market.

 

[Big_Spark]

Yes, MEM is considered a reasonably good make when it comes to electrical accessories however like MK, are expensive for use in domestic installations (sockets switches etc) MEM are aimed more at the industrial market.

You should take a look at their website, they make some damned good looking wiring accessories these days, and the quality is as good as ever.