Thank you for the update.

How long have these pumps—and this hydraulic skid—been operating? Is this turbine being commissioned or was it recently commissioned? If it was recently commissioned, how long has it been operating?

Has the hydraulic fluid temperature been maintained at the specified temperature, or has it been higher or lower than specified? What is the specified temperature and what has the temperature been maintained at? Has there been any problems with the temperature regulating system?

Did you replace one pump or two? Because I think you said both pumps had failed.

Has the “operation” of the hydraulic pump relief valves been checked? Has the current draw of BOTH pump motors been checked—and if so, what are the current draws and what is the rated current draw from the motor nameplates?

AGAIN, the current drawn by an electric motor is directly related to the work being performed by the motor. Rated work is done at rated current draw (both numbers are on the motor nameplate). If the amount of current drawn by an electric motor exceeds the motor nameplate value then the device being driven by the electric motor is requiring more power than the motor is rated to produce.

A particular electric motor should be chosen for a particular driven device based on the rating of the device (not always found on the device’s nameplate). But the supplier of the equipment should have known the requirement of the application when choosing both the device and the motor driving the device.

If the device is requiring more power than the motor driving it is rated to produce either the supplier chose the motor incorrectly or the device—and the motor driving it—isn’t correct for the application. OR the device isn’t adjusted properly.

Usually the electric motor will eventually fail if the current drawn by the motor is excessive (exceeds the motor nameplate value), but sometimes the device can fail if it’s producing more power than it’s rated for. If the axial piston pump is producing too much flow because the relief valve is relieving when it shouldn’t be then the pump may fail prematurely.

We can’t know how the pump was disassembled or inspected but it’s difficult to understand two pumps failing at nearly the same time. It’s possible BOTH pumps and motors were not properly sized for the application—but that means if the same pumps were used to replace the previous pumps they are going to fail as well, eventually.

Best of luck!

@"WTF? Thank you for your interest. To answer your questions,
This Turbine was commissioned at 2012. This hydraulic skid belongs to the same time. as per OEM manual hydraulic fluid temperature range is between 38 to 55 Degree centigrade. Hydraulic oil temperature was on the high side (Maximum 51 degree) during last few days operation. Oil cooler was partially dirty which might be the cause behind that.

We replaced one pump for now and kept the system running. We are trying to find out what happened with the pump in between.

Operation of relief valve has been checked and found no abnormalities. The characteristics of the current drawn by motor was explained in reply of one previous question. After installing new pump, motor is taking normal current which is 20 A. I think the Electric motor that has been installed in the system is properly sized since the system is running for so long. Motor didn't stop during previous occasions only pump's pressure failed which indicates that the problem is in the pump.

It's not the fist case where these pumps failed. During previous occasions, after disassembling pump we found error in the pump. sometimes it's swash plate, sometimes piston shoe, sometimes bearing or shaft etc. On those occasions, Pumps pressure didn't build up at all unlike this time.

Thank you again

 

Is the hydraulic fluid regularly tested? I’ve experience with many axial piston pumps and never encountered failures such you list. A broken compensator spring and worn seals—the latter attributable to dirty oil—are the only two problems I’ve ever experienced. (I experienced failed nylon couplings for a few systems but that was traced to a supplier quality issue and not a pump or oil problem.) And you say you’ve experienced failures of this pump in the past. To me that would suggest one of two things—dirty oil or the wrong pump was selected for the application. The pump motor may be correct or even over-sized, but if the pump isn’t properly rated for the flow-rates at the system pressure then it can fail prematurely. Generally Parker pumps are good quality in my experience, at least in the past.

I would strongly suggest your hydraulic fluid cleanliness may be an issue based on the prior findings when the pumps were disassembled.

AND, also, contact the hydraulic skid manufacturer and Parker to determine if the pump(s) are properly sized for the application in light of multiple failures (especially if you believe the hydraulic fluid testing and maintenance is good and not at fault). Most manufacturers offer assistance with selecting pumps, which some companies choose not to use, and will also help with reviewing systems experiencing problems. If Parker won’t help get a different pump manufacturer’s representative to assist with a review. Something seems to be amiss, in light of the fact you have experienced multiple failures in a relatively short period of time with a critical system.