while Gas turbine is running full speed sometimes giving speed deviation N1 and shut down.

I checked speed sensors. The speed sensors contacted Beckoff signal contioner card (KL5151) and inremental card. I checked speed transducer kHz/4-20mA, and analog input card. I didn't solve this problem.

The problem occurs are sometimes nearly 8 hours some times nearly 2- 3 days.

What else should I check?
What could be the problem?

 

farikhem,

I'm not too familiar with Solar turbine controls (though I am endeavouring to learn more), but there are a few basic things to check.

Speed pick-ups usually fall into one of two categories: active or passive. Active speed pick-ups require an external power source (often, 24 VDC) to produce an output. Passive speed pick-ups do not require an external power source, and develop a small AC voltage output when the teeth underneath it are rotating.

If the speed pick-ups at your site are active pick-ups, the problem could be with the power supply, having an intermittent output. A quick review of the Beckhoff KL5151 reveals it has a 24 VDC output for "encoders" connected to it.

You also mentioned a frequency to mA converter (maybe two converters, or a two-channel converter). Many times these also require external power.

I would suggest, first, checking to make sure that the shield drain wires of the cables used to connect the speed pick-ups to the control system are properly grounded--meaning, the shield drain wire of each interconnecting should be connected to ground (earth) at one end, only. (Shielded cables, two-conductor, or three-conductor, should be used for connecting the speed pick-ups to the control system, and the cables should each have a bare conductor called the shield drain wire--which should only be grounded (earthed) at one end. If the shield drain wire is earthed at both ends, circulating currents can cause problems.)

Next, it would be a good idea (when the unit is not running) to use a meggar to check the interconnecting cables (when both ends are disconnected from the control system and the speed pick-ups) to make sure the cables haven't gotten damaged.

All terminals should be checked for tightness--not gorilla tight, but firmly tightened. Any crimp-on terminal lugs should also be checked for tightness and replaced if necessary.

Many speed pick-ups have screw-on connectors for ease of replacement; moisture can cause corrosion of the pins/sockets.

If all of the "simple" stuff is verified to be good, then I would start replacing the control system components--one at a time.

Please write back to let us know how you fare!