3-Phase / 400V ring main

[Sumo]

Hello,

New here, but hopefully someone can help...!

We have been tasked with installing a number of very small pumps (21 in total) on a large site. Running individual cables to the 7 areas (3 x 1.0kW / 400V / 3phase / DO.L. pumps in each area) where these pumps are located would be expensive.

I would like to install a 3-phase & neutral ring main but I'm unsure how to calculate this for volt drop / current carrying capacity. If I were to proceed this way the end to end (circular) length of the ring would be around 2000 metres...

Any suggestions?

Cheers, Sumo

 

[Darkwood]

2km ring main! is this correct?

What are the pumps doing?
Will they all come on together?
Any other power requirements in the same areas for lighting, power etc even if only for maintenance reasons?
Any equipotential bonding requirements where these pumps are situed'?


Before advising we need to get as much info as possible to avoid wrong advice due to lack of info.

Lastly what is your experience in this field and what is your normal working environment so as to tailor our advice.

Lastly again welcome to the forum.

 

[Bobster]

Also why do you need a neutral? For the length of run your suggesting a small 400 - 230 tx in each panel will be cheaper than 2km of an extra core.

 

[telectrix]

what use is a 400/230V tx to 400V 3 phase motors?

 

[Knobhead]

A lot more information needed.

 

[ian.settle1]

Hello,

New here, but hopefully someone can help...!

We have been tasked with installing a number of very small pumps (21 in total) on a large site. Running individual cables to the 7 areas (3 x 1.0kW / 400V / 3phase / DO.L. pumps in each area) where these pumps are located would be expensive.

I would like to install a 3-phase & neutral ring main but I'm unsure how to calculate this for volt drop / current carrying capacity. If I were to proceed this way the end to end (circular) length of the ring would be around 2000 metres...

Any suggestions?

Cheers, Sumo

You real or just extracting the urine?

 

[Marvo]

I'd be interested to know why you think a ring main would be the best method of distribution.

 

[Sumo]

Basically, it's a large quarry (hence the 2000m run if we did it as a ring) where there are 21 dewatering wells currently being drilled. There are 7 different locations, each location having 3 wells. We plan to install borehole pumps and install a small 4-way (3ph) DB at each of the 7 locations, these DB's in turn feeding 3 local DOL pump panel.

We normally run radial feeds to pump panels / DB's... However, the customer wants to keep costs to a minimum and I hope a ring main may do that.

The alternative is a huge radial which would be around 1600m in length to pick up the 7 separate locations.

As the pumps will be controlled individually via pressure transducers it is possible (however unlikely) that they could all start at he same time. Pumps range from 0.5kW (15 pumps) to 1.1kW (6 pumps)

Many thanks

 

[telectrix]

string some 11kV round on poles and transform down at each location. :ack2:

 

[Bobster]

what use is a 400/230V tx to 400V 3 phase motors?

There must be a reason he wants to run a 3ph + N. I'm guessing for control/instruments.

You disagree?

 

[Engineer54]

Hasn't the quarry company got an Engineering dept at head office with Electrical Engineer(s) to sort this problem out or at the very least give the site staff guidance??

 

[Knobhead]

The quarry can’t be that large if that’s all the dewatering required.

If it’s for clearing surface water from the quarry floor you will need sludge pumps because all the crap will work its way to the drainage sumps blocking the pumps.

If you’re trying to lower the water table to allow deeper benching, you’ve no chance with them. To lower the water table the quarry will need an abstraction licence which won’t be easy to get.

What will be done with the run off, it needs to settle before it goes in to any watercourse.

Get an engineer that knows what he’s doing because you are talking nonsense.

 

[Rockingit]

Ermm.... OK, I know nothing whatsoever about quarries. But I do know a lot about this forum, and it seems to me that we have an OP that clearly isn't electrically unskilled, asking a very specific question having given a reasonable enough amount of information and explanation and yet is being treated as though they were a Electrical Trainee.

The OP may/not be doing this in conjunction with M&E somewhere, or it may well be that they are the first 'face on the scene' and are trying to think of suggestions to progress up the line, but either way I personally don't think the question is unreasonable, even if the answer arrives at it not being the solution to their problem.

Surely it would be a good exercise in education for many others on here (myself included) to do the maths/scenario on this from those on here who are experienced in this area?

 

[Brightspark2]

^^^^^^^^^^^

That was just meant to be a like not a thanks, but tapatalk won't let me remove it.

So also thanks to tapatalk....for nothing...

 

[Knobhead]

Water and industry are a legal mine field, never mind the practicalities.

Any number 1KW pumps aren’t going to cope no matter what. The simple reason being, it won’t be clean water. At times it will be like sludge. We had about 500HP of pumps just for the surface run off. This was settled and went in to the process.

We only had one bore hole pump to provide some of our process water. 60HP didn’t even make a dint in the water table. If it had we would have been in breach of our abstraction licence and would have to shut down.

If you start playing around with water levels you can find yourself in hot water (excuse the pun). The legal side will be the quarry owners problem but the practicality side seems to have landed in the OP’s lap.

The worrying bit: Someone must have “designed” (I use the word loosely) this set up, why is the OP trying to sort out the electrical side. As E54 said they must have an engineering department.

I have installed LV 3Ph rings, but they have always been “open ring” with two feed in points. In the event of a cable failure a section can be isolated while the rest caries on regardless.

 

[Silly Sausage]

Surely it would be a good exercise in education for many others on here (myself included) to do the maths/scenario on this from those on here who are experienced in this area?

I'll happily do it...if the OP wants to pay me £75 per hour






(Cash in a brown envelope, please)

 

[Knobhead]

Surely it would be a good exercise in education for many others on here (myself included) to do the maths/scenario on this from those on here who are experienced in this area?

I'm with Archy on that, if he wants the system designing he can pay.

The amount this madcap idea will cost a consultants fee will soon be recouped in saved capital expenditure.

 

[Simonslimline]

Water and industry are a legal mine field, never mind the practicalities.

Any number 1KW pumps aren’t going to cope no matter what. The simple reason being, it won’t be clean water. At times it will be like sludge. We had about 500HP of pumps just for the surface run off. This was settled and went in to the process.

We only had one bore hole pump to provide some of our process water. 60HP didn’t even make a dint in the water table. If it had we would have been in breach of our abstraction licence and would have to shut down.

If you start playing around with water levels you can find yourself in hot water (excuse the pun). The legal side will be the quarry owners problem but the practicality side seems to have landed in the OP’s lap.

The worrying bit: Someone must have “designed” (I use the word loosely) this set up, why is the OP trying to sort out the electrical side. As E54 said they must have an engineering department.

I have installed LV 3Ph rings, but they have always been “open ring” with two feed in points. In the event of a cable failure a section can be isolated while the rest caries on regardless.

Out of interest, would this be the same for linking Dyn11 substations together? (except the voltage is not LV)

 

[Bobster]

Out of interest, would this be the same for linking Dyn11 substations together? (except the voltage is not LV)

Similar, a few more considerations are needed.

 

[Knobhead]

It’s quite a common practice to get a network up and running following a fault. But as RoB said, there’s a bit more to it if you want to stay alive. I can’t say it was one of my favourite pastimes.