Jacking oil Pump

Dear,
I want to share an issue/observation last week stop one gas turbine frame 9e.03 when it reached turning gear Bearing lift pump comes in operation at 128rpm. Turning normally engage at 130 rpm till 15 mint turning gear was running normal and torque angle was 43 degree
suddenly Bearing lift oil pump stop but turning was continue we checked all alarm. at the time RPM was 150rpm means 5% speed of rotation after bearing pump stop alarm was appeared pump stop and low pressure alarm on list. according to trend we put speed % , pump running status, 20tu torque converter filling and drain valve. all parameters found normal I want to know what could be the reason of stopping Lifting pump while turning is in operation. Normally Pump only stop when pump lost due to pressure lost. kindly share your opinion about this issue if ever you have saw. attached graph for reference
 

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Dear,
I want to share an issue/observation last week stop one gas turbine frame 9e.03 when it reached turning gear Bearing lift pump comes in operation at 128rpm. Turning normally engage at 130 rpm till 15 mint turning gear was running normal and torque angle was 43 degree
suddenly Bearing lift oil pump stop but turning was continue we checked all alarm. at the time RPM was 150rpm means 5% speed of rotation after bearing pump stop alarm was appeared pump stop and low pressure alarm on list. according to trend we put speed % , pump running status, 20tu torque converter filling and drain valve. all parameters found normal I want to know what could be the reason of stopping Lifting pump while turning is in operation. Normally Pump only stop when pump lost due to pressure lost. kindly share your opinion about this issue if ever you have saw. attached graph for reference
Ghulam,

Thank you for sharing such issue.

Would it be possible to get same trends but only for one motor ( Runing motor) as trends are little bit confusing .

Also if you can capture ( pump pressure), it would be great.

Is that a ELin/Ge/Alstom generator ?

Without be able to check, your unit app code, we cannot make more comments at this time.
 
Dear Thanks for reply This Generator Belong to GE. as this system is only locally monitor it don't have any graphic on Mark 6e. we have only low pressure switch for switching the pumps when it get low pressure alarm. the scenario which happen on machine was latest 9E machine GE modified Logic to start Bearing lift oil pump on 4.5% speed lets see 128RPM. and turning engage at 129rpm. and keep on slow rotation for cooldown the rotor temperature. I just want to know during turning gear when this pump can get auto off. what could be a conscience for stopping lift oil pump.
 
Dear Thanks for reply This Generator Belong to GE. as this system is only locally monitor it don't have any graphic on Mark 6e. we have only low pressure switch for switching the pumps when it get low pressure alarm. the scenario which happen on machine was latest 9E machine GE modified Logic to start Bearing lift oil pump on 4.5% speed lets see 128RPM. and turning engage at 129rpm. and keep on slow rotation for cooldown the rotor temperature. I just want to know during turning gear when this pump can get auto off. what could be a conscience for stopping lift oil pump.
Ghulam,

Thanks for this reply.

Okay now I guess that you can get, such informations by reading OEM O&M at least, or go through App code for getting better unedrstanding of this operation mode.

I don't have access to any frame 9E O&M or appcode, so I cannot comment more than this.
 
hello,
We have GE frame 9e gas turbine with a generator. generator auxiliary systems consist a jacking oil pump system which operates at 241 bar. we observed failures of jacking oil pump frequently. can i get to know the possibilities of failures?
 
Hello*E

Can you tell us who is OEM of the Generator auxiliaries ( is That ELIN/GE /Alstom?)


Is that GE energy europ products based in Belfort France the OEM of this frame9E?

If yes did you contact them for getting more informations /assistance on this issue...?

Regards,
ControlsGuy25
 
Presuming the unit has a separate jacking oil pump, and does not use the Aux. Hyd. Pump motor for developing jacking oil pressure:

1) Exactly what is failing: the jacking oil pump itself, the pump pressure regulator/relief valve, the pump motor, the coupling between the motor and the pump?

2) Have you checked the currents being drawn by the jacking oil pump motor to see if they are more or less than the motor's nameplate?

3) When is the jacking oil pump shut down during a START sequence (at 50% TNH; 60% TNH; 95% TNH)?

4) When is the jacking oil pump started during a normal STOP sequence (at 95% TNH; 60% TNH; 50% TNH; 10% TNH)?

5) How long does the unit (turbine and generator) remain on COOLDOWN between shutdown and START? 24 hours? 48 hours? Multiple days?

6) How long is the unit operated on COOLDOWN prior to a normal START (4 hours; 8 hours; 12 hours; 24 hours)?

7) What kind of cooldown mechanism is provided with the unit--hydraulic ratchet, or turning gear, or ???

8) Have you verified the pressures at all the bearings where jacking oil pressure/flow is provided? Are there any regulators at these bearings and if they are adjustable are they verified to be operating correctly?

9) Is there any excess leakage from the bearings where jacking oil pressure/flow is provided?

10) Finally, AND MOST IMPORTANTLY, when did this problem start? How long has the unit been in service since original commissioning? Has the turbine control system been replaced or upgraded since commissioning, and if so, is the new turbine control system also a GE Mark* turbine control system?

By telling us what, precisely, is failing we can better respond to your query. By providing us with the jacking oil pump motor nameplate data (specifically, the rated current draw and capacity (HP; kW) of the jacking oil pump motor AND the actual currents (of the three phases--presuming the jacking oil pump motor is a 3-phase AC (Alternating Current) motor)--we can possibly provide some indication of the possible causes of failure.

Current draw of an AC motor is about the single most important indicator of proper driven device operation. Most people think an AC motor will not produce more power than it is rated to produce--which IS NOT true. Particularly if the driven device is some kind of positive displacement pump. The power required by a pump is in direct proportion to the flow being supplied by the pump, and if the flow is excessive (more than the pump is rated for) then the AC motor driving the pump will be supplying that power--which will usually also be in excess of the motor's nameplate rating. And, this excess current will eventually cause overheating of the motor, if the thermal protection of the motor is not working or sized properly. If the current being drawn by an AC motor is much less than the motor's nameplate then the motor is not supplying rated power--because the driven device (pump, for example) is not providing rated pressure/flow. So, checking motor current draw is very important in understanding how the driven device is working--or not working, as the case may be. Excess current draw may also result in coupling failures (especially if the coupling is rubber or nylon or some similar construction/material).

By providing some information about how the turbine control system is programmed to operate (start, stop) the jacking oil pump we can possibly provide some details about the programming.

However, this is a controls-related forum, and it's not likely the turbine control system is causing jacking oil pump failures--particularly if it is a GE Mark* turbine control system and the programming of the jacking oil pump system has not been altered since commissioning. If the failures of the mechanical components are occurring, it's not very likely that factor-supplied programming of the GE Mark* turbine control system are causing those failures--presuming the unit is being operated according to manufacturer's guidelines.

BUT, if you want more information and assistance, we need more information. Full stop. Period. Answer all the questions, even if you think they aren't relevant (we don't know what you've done to troubleshoot the problem--OR what the results of your troubleshooting have been). We can provide a lot of information and assistance--but not without good data and information to work with.

Adeus.
 
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