pump and motor 3

[Thuba]

Goodday,
l have a pump rated 5 5KW/2900rpm and l plugged 3.7kw/ 2875rpm motor. Will this damage the motor or pump?

 

[Thuba]

Your not using like terms, the pump from India is more than likely Imp gpm and you're using 3960 that is used for USgpm.

l converted from 9m3/h on the pump nameplate to gpm.

 

[Artisi]

Looking at the flow and head on the pump plate, we can assume this is probably performance at its BEP, calculating the power required at this point based on a hydraulic efficiency of 50% equates to ~ 2Kw.
If the pump is now installed for a lower head, the flowrate will be higher, efficiency lower and require more power.

 

[Artisi]

l converted from 9m3/h on the pump nameplate to gpm.

Igpm or usgpm?

 

[Thuba]

In addition, we don't know the SG of the fluid being transported.

its edible oil with S.G.=0.92

 

[Thuba]

Igpm or usgpm?

usgpm

 

[Thuba]

You havent said what supply voltage this motor is hooked up to - it should be 440V or thereabouts, else you'll burn the motor

Another reason motor may be smoking because winding insulation has failed?

l measured the average voltage using a multimeter and it was 388V

 

[Artisi]

its edible oil with S.G.=0.92

And it's viscosity?

It's like squeezing blood out of stone getting usefull data.

 

[Artisi]

l measured the average voltage using a multimeter and it was 388V

That results in higher amps.

 

[Thuba]

Managed to get qvc people on whatsapp number. Here is their response:

"At duty condition it is about 38% maximum for this pump is 58% approx."

Just wondering how they obtained the 38% on duty point, meanwhile we calculated it as 17.3%. Not sure if the head in the equation will include system head too!

 

[Artisi]

Managed to get qvc people on whatsapp number. Here is their response:

"At duty condition it is about 38% maximum for this pump is 58% approx."

Just wondering how they obtained the 38% on duty point, meanwhile we calculated it as 17.3%. Not sure if the head in the equation will include system head too!

What duty?, the Q / H stamped on the pump name plate.

 

[Artisi]

How about you tell us what the operating flow and head is for the system your pumping on.
At the moment noboby has a clue as to what is going on plus you just keep dropping in random not necessarily connected pieces of information.

It's pretty simple actually, even if just reasonably close approximation.
1 Head
2 Flow
3 SG
4 Viscosity
5 temp
This will help in getting somewhere near to the problem.

 

[Thuba]

What duty?, the Q / H stamped on the pump name plate.

 

[Thuba]

How about you tell us what the operating flow and head is for the system your pumping on.
At the moment noboby has a clue as to what is going on plus you just keep dropping in random not necessarily connected pieces of information.

It's pretty simple actually, even if just reasonably close approximation.
1 Head
2 Flow
3 SG
4 Viscosity
5 temp
This will help in getting somewhere near to the problem.

sg=0.92, Flow =9m3/h, temp =110-120Deg C, head =40m, viscosity -unknown (soybean oil)

 

[LittleInch]

sg=0.92, Flow =9m3/h, temp =110-120Deg C, head =40m, viscosity -unknown (soybean oil)

Thuba,

I'm really struggling to believe that those numbers you wrote are the ACTUAL OPERATING CONDITIONS

NOT what is printed on the pump dats sheet.

 

[pierreick]

Hi,
Soybean oil viscosity @ 90 C : 8 mm2/s , it depends very much about the age and the impurities within the product..

Viscosity levels of oil products

www.lauda-scientific.de

Note: already 53 replies on this post!
Purchase a power meter (clamp) to measure the power if needed and make sure the protections of the motor are in place to prevent motor damage prior to test.
Without a PID /Isometric /curves of the pump, there is no way to get a meaningful answer, just guesses!
Pierre

 

[Artisi]

Hi,
Soybean oil viscosity @ 90 C : 8 mm2/s , it depends very much about the age and the impurities within the product..

Viscosity levels of oil products

www.lauda-scientific.de

Note: already 53 replies on this post!
Purchase a power meter (clamp) to measure the power if needed and make sure the protections of the motor are in place to prevent motor damage prior to test.
Without a PID /Isometric /curves of the pump, there is no way to get a meaningful answer, just guesses!
Pierre

Correct, crystal ball gazing and guess work for the want of a bit of useful data.

 

[Thuba]

Thanks guys, finally got the pump curve from the company. Hope our conversation will help someone else. For new engineers like me we are sometimes confused with data on nameplates and whats happening physically so. As you can see, with given information on the pump of head 40m and capacity 9m3/h, the motor of 3HP suffices. A novice engineer would then question the 5Hp!

 

[LittleInch]

I'm now wondering if the pump nameplate actually say 3.5 kW as the photo is unclear whether the figur eis a 3 or a 5 when you compare it ot other 3's and 5's on the nameplate.

At 9m3/hr t sure looks like it should be 3.5kW.

But like we keep saying are you measuring the actual flow and are you sure you're actually doing 9-10m3/hr and not 20+ m3/hr??

That pump curve is pretty/ very flat so there won't be much drop off in head / pressure but flow just keeps increasing as does power, though to be fair the efficiency gets better as well at higher flows than 9m3/hr.

So either you're flowing at a higher flow, you've used the wrong connections onto your motor / wrong voltage or your motor is faulty.

 

[Snickster]

The pump nameplate indicates that the impeller size is 173 mm diameter. However, a 173 mm diameter impeller pump curve cannot achieve an operating point of 40 m head at 9 m3/hr flow according to the pump curves you attached. If it were a 173 diameter impeller then based on the curves the pump reach 3.7 kW power at about 43 m head and 14.5 m3/hr flow. If your system head/flow curve is such that you are at this operating point with a 173 mm diameter impeller with a 3.7 kW motor then you will be overloaded. See attached pump curve.

It appears like a 165 mm impeller will get you 40 m head at 9 m3/hr flow. If you really have a 165 mm impeller than as you reduce the head and increase the flow to end of curve, it looks like you will still be just under 3.7 kW brake horsepower so the motor will not be overloaded. So if you installed the pump in as system with lower head loss that it was not designed for you will not overload it even at the end of curve.

The question is - what is the actual size of the impeller in the pump? And what is the actual system curve of where you have installed it. I assume you took the pump form another system and are now reusing it in a system it was not designed for originally.