Vertical pumps tripping
Vertical pumps tripping
(OP)
We run a 2*100 pump skid in our circulating water system for the cooling of our steam turbine.
One of the pumps tripped on high motor current with equivalent high discharge pressure and high vibration,the other pump on auto-standby also tripped within a minute on high electric current,high discharge pressure and high vibration.
I am wondering what might lead to such pump behaviors.We attributed these to the system conditions since the problem was common to both pumps,but after a thorough inspection of our pipelines and condenser tubes,they were found to be okay.
I really need ideas to help resolve this problem.
One of the pumps tripped on high motor current with equivalent high discharge pressure and high vibration,the other pump on auto-standby also tripped within a minute on high electric current,high discharge pressure and high vibration.
I am wondering what might lead to such pump behaviors.We attributed these to the system conditions since the problem was common to both pumps,but after a thorough inspection of our pipelines and condenser tubes,they were found to be okay.
I really need ideas to help resolve this problem.





RE: Vertical pumps tripping
If your pumps have a high head at low/no flow then you could get the same result. The pump curve would be very useful to provide more response. If you don't have it look it up on google and normally you can get a generic one from the vendors website.
If the system was running fine before then you needs to see what changed, even if it looks unrelated and post the results. Pumped systems don't normally just stop working unless some aspect of the system changed.
At the moment it sounds like too much flow or too little flow, but why? - I don't have enough information to guess at the moment.
My motto: Learn something new every day
Also: There's usually a good reason why everyone does it that way
RE: Vertical pumps tripping
Also, new installation or an existin installation that was running fine for awhile and this just showed up? Like LittleInch mentioned, more details are necessary to come up with some ideas why it's happening.
RE: Vertical pumps tripping
Those tend to have decreasing BHP with increasing flow as shown in fig 7 here:
http://locator.gouldspumps.com/cpf_0009.html
Then high discharge pressure (low flow) would be consistent with high motor current. System blockage is suspected.
If system didn't change, let me think about increased fluid density due to decreased temperature. That would cause increasing discharge pressure and increasing BHP for a given system.
All above assumes fixed speed pumps.
If you have variable speed pumps, of course increasing speed results in both increased dp and increased bhp... look into the control system for speed and what it's sensing.
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(2B)+(2B)' ?
RE: Vertical pumps tripping
RE: Vertical pumps tripping
My motto: Learn something new every day
Also: There's usually a good reason why everyone does it that way
RE: Vertical pumps tripping
I appreciate your inputs so far.I hope these additional information can help.
will do my beat to send the pump curve.
RE: Vertical pumps tripping
However, for the flow and head advised probably axial or very mixed flow impeller, this being the case - if axial, power will rise as head increases and flow reduces, if mixed flow depending on design, they too can perform in a similar fashion with power rising and head increase.
You need to give more detail on pump configuration / manufacturer / model etc.
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.)
RE: Vertical pumps tripping
Everyone is of much the same opinion here that for this type of pump, the symptoms you describe (high current + high vibration + high pressure) are all symtomatic of very low or no flow occurring. Therefore you need to look at or post your system and try and see how this could have occurred. Usual things to look at at blocked filters, closed valves, low inlet water level, control valves closed - that sort of thing.
My motto: Learn something new every day
Also: There's usually a good reason why everyone does it that way
RE: Vertical pumps tripping
I have been out of town for sometime now that is why I have not replied.
These pumps are vertical axial flow centrifugal pumps.
Presently,the problem has stopped after we performed the following;
1. cleaned the steam turbine condenser outlet to the cooling tower of scale deposits build-up.You know,its a circulating system which works as follows;
cooling tower basin seawater(lower temp) pumped by the pumps described earlier to the condenser,then the higher temp(after heat exchange with the exhaust steam) water moves to the cooling tower for heat extraction and the process continues.
2.Cleaned the condenser tubes which were found to be very clean and void of dirt build up and scales.Only little traits of Calcium deposits.
3.Emptied the basin and refilled with fresh seawater.
The pumps were started successfully and the current reading is presently 190 Amp,which is the normal running current.Its has been stable for a week now and we are still monitoring to see any change.
Can't specifically point on the actual cause but we still open to your inputs and ideas as we continue to troubleshoot and monitor.
RE: Vertical pumps tripping
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.)