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Irrigation Pump


Dairyspark

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Hi all, I was asked to go and look at an irrigation pump at my local golf club, after contacting the manufacturer they haven't been very helpful so far so I was thinking of a solution, it currently uses a frequency converter to control the motor, however if I cannot find a replacement unit, would it be possible to just change it to a start/stop contactor, it's a 7.5kw 3phase pump so possibly a star/delta would be needed, the greenkeeper isn't fussed about the speed control as they run it at full tilt all the time to pump water tot eh far end of the course. Any help on this would be greatly appreciated.

Cheers

Bobby

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You can swap it to DOL, but keeping the FC would pay for itself in energy costs.

Why can't you get another FC?

They are all interchangeable pretty much, especially for standard squirrel cage motors.

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I was looking for a direct replacement as it has a multiplug style connection directly onto the motor and didn't know how easy it would be to install a new FC but if I removed the cover to get into the terminal block of the motor I could convert it to DOL, I can post a picture of the full set up to show you what I'm working with?

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What FC is it?

By all means post up what you want, the more info we have, the more advice we are able to give you.

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Think it's worked lol

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The pictures I have are too big to post, any ideas as to how I can post them?

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Downsample, or use something like photobucket?

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Front of motor/control panel

IMG_0210.jpg

 

 

Whole Setup

IMG_0206.jpg

 

Motor data plate

IMG_0205.jpg

 

Hope this helps

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Thats just a standard Grundfos pump motor drive unit.

Inverter repairable, or replaceable, I think.

The whole unit would an off the shelf item from Grundfos anyway.

I'd go for the brown & black on 7 & 8 being the pressure switch at the top of the unit.

What is the fault?

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That's what I'm trying to get from them, I've gave them photos of every data plate I can find on the thing and they say the still need more information about what pump it is, I don't know what else to tell them haha, yeah that's the pressure switch and that fault is that nothing happens, when the power is turned on the motor doesn't start, the lights on the unit don't light up and well nothing happens lol

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It's a multi-stage centrifugal pump.

It will be pretty standard.

Get a catalogue and a tape measure

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get a few of these instead?

 

0137542_l.jpg

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I'm going up tonight to see if I can get anymore information from the whole thing, all I want from them is information as to whether this is a common fault and here's the part you need or that sound alike the whole controller is knacked and you need a new one, here's where to get it

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The pump looks like it's a grundfoss CR range from the photos. If it's a 7.5kW motor it will be a CR-5 or maybe a CRI-5 which is a clean water 13 stage centrif pump.

I have a datasheet for the full CR range if you want it but you'll need to give me a gmail address cause it's a 2849kb pdf which is too big to attach to the forum.

The motor is a standard Grundfoss as well and will probably have been supplied as a complete unit with the pump.

The controller is also a soft start so if you're going to bypass it and go DOL just check that the supply is capable of the inrush and start current.

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Looking at the other data plate it seems you're correct And that's you just looking at the photos I've put up, why couldn't they work that out?

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so how would you test the motor? I'm assuming looking for IR failure between coils, but as this something I never do I'm interested in 'best practice'

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I'm not entirely sure what the fault is, when power is applied to the unit nothing happens, but at the inverter is mounted on the pump I'm making a guess that since the front of the panel is not illuminating then it's incapable of doing anything, they said to me that it was running fine all last summer, and when it came to winter time it's not needed due to us living in Scotland and well, rain is our national weather, so the greens water themselves, and when it started to dry up in the spring the head greenkeeper went out to start the pump but nothing happened

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Looking at the other data plate it seems you're correct And that's you just looking at the photos I've put up, why couldn't they work that out? and I've sent them the picture of the data plate so I'll see what they come back with tomorrow, in all honestly I would like to keep it standard as it will make it an easier job by just fitting the new control unit

You were just lucky.....or I was just lucky, I installed one 4 or 5 years ago and I remembered it.

I've emailed you 3 times with several different documents attached. I don't have info on the inverter drive though but that shouldn't be difficult to find on the web. As Canoe says, the inverter might have shut down or tripped internally to a motor fault and there's always a good chance that a motor fault can be caused by the wet end either having mechanical problems or running outside of it's spec ie low head (npsh) etc. Don't just replace the inverter without getting the other components on a bench first.

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Get to the motor leads and disconnect them from the inverter

Test for IR between Windings and Earth and Windings to Windings (only possible with 6 leads)

Test Resistances U1-U2 V1-V2 W1-W2 (all should be roughly the same)

Test for shorted windings and rotor faults - Special motor tester required

The only thing that I can add is that in the absence of the special motor tester is to do inductance & capacitance readings as per the low resistance checks & compare them in the same way.

That will give you a further indication of the motor condition, not as good as the dedicated tester though.

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If you don't receive 5 pdf files spread across 3 emails please let me know.

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I received your emails thank you very much :) and I also got an email back from the company with an answer of, all we can do for you is send our engineer to look at it for a cost of £308+vat and then any parts and labour after that are charged separately, so I'm not sure even if I diagnosed what was wrong with it that they would then supply the parts to me lol

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If you can diagnose the fault, many of us can get the parts, I've never had that from Grundfos, (industrial) but, I've not dealt with them for a few years.

Let them get on with it, shadow the guy on the ground, you'll learn a lot, and it's not your money, golf clubs are loaded, use it as a learning job, and just do the arranging with the clubs permission, to save them their labour costs on that, you'll get that value back in experience.

Most service guys are really helpful once they get on to site.

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I'd very much like to take the motor off and have a look at to however as it's an after work job I don't have the time but if they are willing to wait then I'll do it, and if possible I'd like to shadow the engineer, I do the same with the commissioning engineer from MTU and 90% of the time he gets me to do the work which is great :) I'll keep your up to date with what happens :) thanks for all the help, much appreciated as always

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I spoke to one of my pump suppliers about something today and asked him to have a look at your photographs. He laughed, it's not the kinda thing that's popular in this neck of the woods.

Apparently this a high efficiency pump that has a special class of high efficiency motor so you can't just fit a standard Grundfos motor as a replacement.

The speed control inverter also can monitor bearing condition and can be programmed as auto constant pressure or auto constant volume if it's set up with the required extraneous transducers. It stores the last causes of failure or alarm in its memory but you need a special plug in interrogation unit to read them unless it has a remote infra red controller in the office or plant room in which case you can also read them on that as well. The inverter can also be set up as dry run protection and can monitor phase angle and alarm accordingly.

TBH, if it was my problem and the inverter wasn't being used for constant control with transducers I'd check for obvious trip or fuse issues with the inverter and if it's something complicated I'd remove and go DOL. Run the basic motor winding tests and check the bearings are smooth. I'd run it and check the pump cycle times under normal operation during the irrigation cycle and if they were within the spec of the motor I'd leave it at that. Maybe just for a laugh I'd get a quote from the agents for a diagnostic visit and replacement inverter and offer it to the customer as an option.

Edit..Obviously make sure there's dry run protection, if not then just add some.

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Nothing like an easy job

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