Pump motor high current

[bb1974]

hi sir,

I have a vertical sea water pump ,after overhauling the motor and the pump. The pump is taking more current. before overhauling it was 72 amps after overhauling 93 amps. no change in flow rate /pressure etc. I have checked the overhauling data all clearances are within limit.Pump is free. Motor changed but still same trouble.

what will be the reason. can you help

 

[ashtree]

You say that the pump was overhauled. Do you know exactly what was done?
The pump is type you say is a vertical sea water pump. I assume that is a vertical multistage, but is it submersible , close coupled , or line shaft drive?



Regards
Ashtree
"Any water can be made potable if you filter it through enough money"

 

[desertfox]

Hi BB1974
When it was all reassembled how was the motor and pump shaft coupling aligned?

“Do not worry about your problems with mathematics, I assure you mine are far greater.” Albert Einstein

 

[Artisi]

are you sure of flowwrate and head, has it been measured?
is the pump running in the right direction - check it - don't take anyone's word - yes it is - physically check it yourself.

It is a capital mistake to theorise before one has data. Insensibly one begins to twist facts to suit theories, instead of theories to suit facts. (Sherlock Holmes - A Scandal in Bohemia.)

 

[bb1974]

hi ashtree ,

yes it is multisatge , line shaft drive and submersed pump. We just replaced the werrings. All other parameters are within limit.
Pump direction is ok. it free also.
is there any hydraulic friction caused due to some wear on the impeller surface?

 

[John2025]

You said the motor was replaced and the problem remained, that would seem to rule out motor problems. Did they replace the impeller? if so, was the old one different/custom? Did someone open a throttling valve in the system, thinking it should be open?

 

[Artisi]

Did you checked flow and head - prior to overhaul and in overhauled condition, is the motor overloading. do you have original data sheet giving flow / head and power requirement?

it stand to reason that new wear rings will / should give you higher flow / head with an increase in power input.

Edit: to highlight John 2025 comments.

It is a capital mistake to theorise before one has data. Insensibly one begins to twist facts to suit theories, instead of theories to suit facts. (Sherlock Holmes - A Scandal in Bohemia.)

 

[JJPellin]

Radial wear rings on both sides of the impellers? Lateral wear rings? Balance holes? OEM recommended lift setting? Installed lift setting? How many stages? Impellers keyed or collet driven? Did you check the motor amps on all three phases or just the one that happens to have an amp meter on it? Did you verify amps with a clamp on meter?

Possibilities given the scant information provided:
[ul]Dropped an impeller because of poor assembly of collet
Bad amp meter
Bad electrical connection causing high amps on one phase
Incorrect lift setting with lateral wear rings[/ul]


Johnny Pellin

 

[keyepitts]

Why was the pump/motor overhauled? From the data that you are giving us, it worked better before the "overhaul". I would guess that either something was re-assembled in the incorrect position, or with incorrect clearances, which is causing physical rubbing during operation, or internal re-circulation of product. Does the pump vibrate?

 

[EdStainless]

It is higher because you are moving more water.
Artisi is right on the money here.
I'll be that the old one was bypassing/recirculating like crazy.

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