Diversity

[Sidewinder]

I've recently been asked if it is OK to apply diversity to the supplies for washing machines & tumble dryers going into an industrial/commercial premises for their in house laundry.

The washing machine s are 21kW, & the dryers 30.8kW.

Any thoughts, bearing in mind that I believe they could be used at the same time, but we are only talking 2 of each.

I could not give a straight answer immediately to be honest, & still can't decide.

Discuss?...

 

[OnOff]

Surely the OSG is pretty clear on this? Business premises. The assuming they are "instantaneous" water heaters then 100% f.l for the first and 100% f.l for the second.???

 

[ProDave]

I've recently been asked if it is OK to apply diversity to the supplies for washing machines & tumble dryers going into an industrial/commercial premises for their in house laundry.

The washing machine s are 21kW, & the dryers 30.8kW.

Any thoughts, bearing in mind that I believe they could be used at the same time, but we are only talking 2 of each.

I could not give a straight answer immediately to be honest, & still can't decide.

Discuss?...

Yes.

I assume at that power rating they are 3 phase machines. That still adds up to 103.6KW or 143A per phase total.

Lets hope it's at least a 200A per phase supply.

If heaven forbid they are single phase machines then one phase will have to have the two washers at 42KW or 175A

 

[sellers]

I suppose they are very likley to be used at the same time.  Unless you fit some kind of change over switch to a pair of washer and dryer.

 

[SLIPSHOD & SLAPDASH]

Thought of the day.

Why would they pay all that money to have 2 machines and only want to  use 1 at a time.

 

[sellers]

Thought of the day.

Why would they pay all that money to have 2 machines and only want to  use 1 at a time.

I was thinking using 2 washers at once, followed by 2 dryers, 4 machines, used 2 at a time.

 

[Phoenix]

I think perhaps some diverisity is applicable to the washers, but not the dryers. As washers will not be heating all the time, but rather just washing about and spin drying a lot of the time.

Also look into the cycle times and loading capacity of machines, it might be the case that when the laundry is opperating at fully capacity they are able to move loads through one part of the process faster than the other, and with all items requiring both process, it means there is going to be some idle time on the other process.

Gut feeling is that they'd be alright on a 100A TPN submain to the laundry room, but I'd not want too much else on the same board, and I'd oversize the incomming main switch on the board, but not sure I'd put my name to designing along those lines until id researched it a little further

 

[septiclecky]

Until the outsoucred the laundry on the site I work there where 3 washing machines and 3 dryers, which where on constantly during Monday to Friday from 07:00 to approx 14:00 so in that case there was no diversity was allowed.

You will need to find out how often and what length of time they are going to be on for before an answer to diversity can be given

 

[kerching]

I would say they will be on full tilt all day

Just a thought.....I know domestic washers are now almost always cold fill, but are commercial ones?...just a thought

 

[Sidewinder]

It's a 1600A/ph supply PD!

Cold fill only!

 

[kerching]

Mmmmm

First wash of the day, cold fill.....so it won't be too bad. BUT assuming first wash goes into dryer as soon as its finished AND washer goes straight back on again Whilst TD is on. Could potentially end in tears

Out on a limb here. BUT. How about a timer so that the TD cannot operate whilst the water is heating in the washer. After it has heated the load should drop quite a bit and only the spinny round and round thing and a few valves working. Or am I talking Political Party Broadcast!

Just thinking

 

[Sidewinder]

The timer bit will be a no-no I believe.

I'll have to look at the job myself I think, not had chance yet.

However, currently thinking along the lines of a 400A Dorman Smith panel board, 400A MCCB incomer, 4x240 tails to the board from the main bus bars, 200A sub main, possibly 250A, out to an IP55 Dorman Smith panel board, then a 100/160A sub main to a Type B board in the Laundry.

Feed the machines from that via MCB's & run the single phase loads off the same board, balancing out as we go, just need to source a big enough 300mA S type 4 pole now from Schneider for the type B, which may need to be a 250A version just because of the RCD, let alone the load.

There will be other loads & the 400A board off the main bus bars will give us spare capacity as the main switchgear is full & to change that is not an option!

Surely the OSG is pretty clear on this? Business premises. The assuming they are "instantaneous" water heaters then 100% f.l for the first and 100% f.l for the second.???

Onoff,

OSG simple supplies up to 100A only!

 

[septiclecky]

If cold fill only then I would say no diversity as it will be a instantaneous water heater as you have to heat the water for each wash setting, you don't know what type of wash will be used or when, due to machine having to heat the water and if they could use the highest temp wash setting 90 deg wash it will nearly be boiling the water.

 

[NozSpark]

I thought that most commercial appliances like these used gas as a heat source and only electrickery for the programmer and spinny motion

 

[Sidewinder]

Noz,

These are lektrikery only!

 

[NozSpark]

Noz,

These are lektrikery only!

 

[Manator]

In this case i would only apply diversity at design level, you could not as you quite rightly say not use the guidelines given in the OSG. To apply any diversity you would have to know the total demand over the wash cycle and the drying cycle, I would assume that this would vary under normal conditions.

It would also follow that the main reason for purchasing two of each is the ability to reduce the waiting times down by using both at the same time.

There are many variables in the calculation, my applied design diversity would have to be based on the maximum demand if simultaneous operation was used over the maximum time these conditions would be applied for.

Example;

Both machines set to operate at the same time, initial water warm up, to maximum temp available time lapse interval.

Peak levels in demand during operation, spin rinse and wash cycles maximum time lapse intervals.

As for the dryers most industrial ones are gas, but I can see why these would have to be electric, these would be pretty much be constant in demand apart from the initial peak to gain the set temperature.

The only gain to applying any diversity would be to use the data to install a cable for example that would allow full demand at or near the cables capacity, or to use the test curve of a lower circuit protection devise to allow the time limits to be controlled at or near the overload disconnection rate.

its not going to be easy to apply diversity in your example, and I do not see any benefit from doing so given the large loadings.