Lake Areation Pumps

[Clinchy]

Hi guys and gals,

I've been asked to install 5 aeration pumps on a large lake. The pumps are 1kw each.

The first pump is 150 meters from the property and the furthest 350 meters.

Can I run these as a radial dropping the SWA CSA as I go, I calc'd the initial run would be in 25 for the first pump then 10 for 2 pumps off the same feed and then 2.5 for the final 2.

I would like to run them so they each have a dedicated feed but it gets expensive.

Any input welcome.

Many Thanks.

 

[davesparks]

Yes you can reduce cable size along the length of a circuit such as this for voltage drop reasons, you must ensure that the smallest cable is protected from fault and overcurrent.

How are the pumps to be controlled? Will they all be started at the same time or different times? If they all start at the same time then the inrush, and increased volt drop, at startup may mean you need larger cable sizes.

Thisay also be a factor if they start individually, if the first four pumps are running and then the furthest one is started the volt drop due to the inrush current may be too much.

 

[Clinchy]

Each one is going to have a rotary isolator on the bank. They don't need to run all the time so he will just walk around on turn them on one by one when needed so can start from the furthest end.

There's an old board in the barn just running a couple of circuits so planning on upgrading that and taking my feed.

 

[davesparks]

Each one is going to have a rotary isolator on the bank. They don't need to run all the time so he will just walk around on turn them on one by one when needed so can start from the furthest end.

There's an old board in the barn just running a couple of circuits so planning on upgrading that and taking my feed.

OK so they won't all be started at the same time, but there is nothing to prevent the furthest one being switched on last so you should design for that situation to occur.

What is providing overcurrent protection for each pump? Is it built in, will you be fitting DOL starters, something else?

 

[David Prosser]

Just out of interest what sort of aeration pump is it?

 

[R-fur]

Could you fit one aeration pump in the barn and run hoses out to the lake?

 

[Clinchy]

The pumps I've been asked to look into are called force 7. They are installed in the lake on a floating system then depth adjustable.

The pumps have they're own controller with RCD, overload protection and timer so I have been informed but I can't think of a way to ensure there is only one start up procedure sequence apart from having it detailed at the supply and each controller.

 

[davesparks]

The pumps I've been asked to look into are called force 7. They are installed in the lake on a floating system then depth adjustable.

The pumps have they're own controller with RCD, overload protection and timer so I have been informed but I can't think of a way to ensure there is only one start up procedure sequence apart from having it detailed at the supply and each controller.

You can't ensure the startup sequence unless there is a central controller with no option of independant starting.

However you don't need this, you know that because of the physical seperation between the controls that they won't all be started at the same instant (well I guess it could be possible if you had 5 people at each control station etc etc)
So you only really need to think about the worst case scenario which, I think, would be the nearest 4 pumps running then the furthest one being started. It shouldnt be too hard to design the circuit to operate under this condition.

Having a sign at the nearest pump telling the operate to work from the other end starting the pumps won't achieve much, the operator will ignore it and start from where they are instead of walking 250metres just to push the start buttons in the right order.

 

[Clinchy]

The circuit I've already designed takes into account the total running load and I've over sized it to be on the safe so would account for an inrush if the pumps are not turned on in sequence.

 

[davesparks]

The circuit I've already designed takes into account the total running load and I've over sized it to be on the safe so would account for an inrush if the pumps are not turned on in sequence.

Is that a calculated oversize or a guess?

2.5 to the last two pumps, assuming they are wired from one to the next doesn't sound to me like it will account for much starting load/volt drop. But then I haven't actually done the calculations so could be wrong.

 

[pc1966]

The pumps have they're own controller with RCD, overload protection and timer so I have been informed but I can't think of a way to ensure there is only one start up procedure sequence apart from having it detailed at the supply and each controller.

You might find they can be configured to wait a certain time before starting on power-up (some UPS have that feature). Then if you set the correct delays you can just operate the main switch and they come up in the best order (e.g. furthest on shortest delay) or at least in some sort of order other than simultaneous!

 

[bill01803]

I would test one of the pumps to see how much current they actually draw on startup, I have had trouble with blowers on sewage tanks drawing alot of current to start

 

[davesparks]

I would test one of the pumps to see how much current they actually draw on startup, I have had trouble with blowers on sewage tanks drawing alot of current to start

Alternatively just read the information in the manufacturers data or ask them for it. It would save a bit of hassle in setting one up with a tester capable of recording the necessary information.

 

[Clinchy]

Well I've been and had another walk and talk with them today and decided to run each one on a dedicated circuit.

Cheers for the inputs everyone