GE-FR5 -MS5002 driving centrifugal compressor in LNG plant
Starting system composed of: Electric induction motor+ hydraulic torque converter+ SSS clutch + accessory gear box.

Finding: GTC starting system fail to continue during acceleration mode and SSS clutch disengaged at %TNH decreased from 54% to 51% then 49% during 3- consecutive starts

Action:
1. Replaced the check valves located on the lub oil filling line for torque converter priming & 20 TU located at torque converter outlet 50.9% starting system disengaged

2. Replaced the torque converter with new 50.9% TNH starting system disengaged

3. No evidence of wear notice for SSS-clutch parts

4. Electrical team confirms that same parameters for starting motor (phase voltage & current value, PF)

Please, your advice?

 

My only suggestion would be to check the adjustment of the proximity switch for the SSS clutch, if that is what is being used at your site. Possibly it is on the edge of being able to sense the position of the SSS, and dropping out for some reason as the unit accelerates?

I would also have to ask when this problem started? Did you do any mechanical work to this machine recently? Who is the manufacturer of the torque converter? Does this unit start often or does it typically run all the time?

The logic I have for a Frame 5 machine uses the indication of the SSS clutch being engaged for control of the starting motor. If the SSS indicates it is disengaged then the starting motor will shutdown.

If the unit is not yet self sustaining then the clutch should not be disengaging. When did the clutch used to disengage on a normal start? On the machines I have seen it is usually around 52-54%, but I have not seen a compressor drive application, they may be different.

Please write back and let us know how your diagnosis is proceeding.

 

Many thanks for your kind support

Recently with reviewing some cases with GE technical support we get the solution. there was an orifice 14mm in the drain line placed in the discharge flange for the torque converter hose. this orifice was missing since the 1st construction.

Now, the machine started properly and 20TU is adjusted to get the old configuration 54%.

 

Dear islaahi78,

thank you for the feedback and I am glad that your issue has been resolved.