If we synchronize the steam turbine with grid at the time when synchroscope is rotating in slow side (anti-clockwise) direction, then our machine tripped on speed controller trip signal. What will be the reason of that tripping?

 

You do know that the steam turbine generator gets its speed increased when the generator breaker closes when the synchroscope is rotating in the anti-clockwise direction? The faster the synch scope is spinning in the anti-clockwise direction the more the speed gets increased—and very quickly.

But you haven’t told us what the turbine control system is, when the problem started (is it recently, or has this been happening for a while or since commissioning), what other alarms are being annunciated when the speed controller trip signal becomes active, if it is being synchronized manually or automatically, how often the machine is synchronized with the synch scope rotating in the anti-clockwise direction. Those are the minimum questions you need to answer if you need more help. We also need to know what has been done to troubleshoot and resolve the problem and what the results were.

Finally, have you consulted the turbine control system manual for troubleshooting information? If so, what have you learned?

 

Issue is since commissioning.
Alarm appeared only Speed controller Trip.
I could not find such thing in manual. Therefore I came here.
Last thing is that either a generator synchronization is possible by anti-clockwise? If yes than how?

 

"Last thing is that either a generator synchronization is possible by anti-clockwise? If yes than how?"

Synchronization is generally possible with the synchroscope rotating in either direction (Fast or Slow; Clockwise or Anti-clockwise). The difference is that when the synch scope is rotating in the Fast direction (Clockwise) when the generator breaker is closed there will be a small amount of positive power (amperes) flowing out of the machine onto the power system/grid, and when the synch scope is rotating in the Slow (Anti-Clockwise) direction and the generator breaker closes there will be a small amount of negative power (amperes) flowing into the generator from the power system/grid. Since generators don't really care if power flows into or out of the generator MOST prime movers driving generators last longer if there is always a small amount of power flowing out of the generator onto the power system/grid when the generator breaker closes. Some prime movers REALLY don't want any power flowing from the power system/grid into the generator at any time--because that means the generator is spinning the prime mover and some prime movers don't last very long when this happens (steam turbines are among the prime movers that really don't like to be spun by the generator with reverse power flowing into the generator from the power system/grid).

The ONLY time I've ever seen generators routinely and consciously synchronized with the synch scope rotating in the Slow (Anti-Clockwise) direction is when the generator rotor had experienced a lot of cracking when the generator breaker was closed when the synch scope rotated in the Fast (Clockwise) direction. Most synchronizers and synchronizing check relays don't care if the synch scope rotates in the Fast or Slow direction when synchronizing; they just require some phase differential (positive or negative) to allow/permit synchronization.

You have chosen NOT to provide any of the requested information, so other than speaking to general synchronization concepts and principles there's NOTHING else we can do to help you. If you didn't find anything in the "speed controller" (which I presume is the steam turbine governor, or control system) manual and you won't tell us the name of the speed controller manufacturer, or if the speed controller is a small part of a larger system that might be annunciated the alarm/trip (such as a DCS or similar controller of which the steam turbine speed controller is a part of) there's really nothing else we can do about the specific problem at your site--except to say get a knowledgeable person to site to observe what's happening and fix or make recommendations about how to fix the problem.