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Synchronization manually
In GE 9fa machine with DLN 2.0+ during synchronization how to observe phase angle in the synchronization Screen.
By Sriram Surya on 2 March, 2013 - 9:00 pm
1 out of 1 members thought this post was helpful...

During synchronization when the voltage and frequency of the system and source matches (which can be observed through parameters on the screen and can be adjusted according to the requirement for proper synchronization)we will close the breaker.

But as the phase angle is also very much important parameter which must be considered while synchronization how to observe it?

I think when the phase angle shows zero we can synchronize(I am not sure)..on the synchronization screen we have phase angle value..

my second doubt is while we are attempting synchronization in Auto if the synchroscope needle rotates in the ccw direction instead of cw...can we consider it as a reverse current??/

Kindly clarify above....your reply makes me more knowledgeable.


Sriram Surya,

If the synchronizing display has a synchroscope on it, it would be very unusual if the synch scope was not also visible on the display during manual synchronization. And, if it wasn't visible during manual synchronization then it would seem the unit was not intended to be manually synchronized from the HMI.

If the synch scope is visible when the unit is being manually synchronized the breaker closure signal should be initiated when the synch scope needle is rotating in the clockwise direction and is at about the 11 o'clock position. (This is necessary because the breaker contacts should close when the synch scope needle is as close to 12 o'clock as possible, minimizing the voltage differential between the generator and the running bus to minimize the mechanical force required to close the breaker and the arc which will occur between the contact faces. And, there is a time lag between when the Speedtronic closes it contact to energize the generator breaker closing coil and when the stored energy in the breaker close mechanism is released and the generator breaker contacts actually close.)

If you are watching the phase angle as the synch scope rotates, you should see the phase angle at 0 degrees when the synch scope rotates through 12 o'clock, increase to a maximum value when the synch scope rotates through 6 o'clock. And then decrease to 0 degrees when the synch rotates back through 12 o'clock. That would indicate the phase angle is an accurate reflection of the synch scope and a valid check of the synch scope. When synchronizing manually, there should usually be two indications of proper phase angle and voltage differential. In the good old days, that was a synch scope and at least one (usually two) indicating lamps.

Further, you should see these same indications when the unit is synchronizing automatically as yet another check.

Finally, when the synch scope is rotating in the counter clockwise direction the generator breaker is not closed so no current is flowing--in any direction. IF the generator breaker were to be closed when the synch scope was rotating in the anti-clockwise direction then reverse current WOULD flow in the generator stator windings.