Whats is the Most Importnat parameters for Synchonization of Two power generating machines?

There are Four Key parameters Associated with Power generatining synchronization These are

1 Volatge

The voltage should be in the range of +_10 % of the bus bar

2 Frequency 

The frequency of incommer unit should be slightly higher than the bus frequency as per standards it should not be higher than 1% higher than Bus.

3 Phase sequence 

Phase sequence of both the units should be same

4 The Phase angle of both generating units should be same. A margin of upto 30 degree is allowed in phase angle.

Must be the same voltage output .

1. Phase voltage

2. Phase frequency

3. Phase sequence

Mr Adnan Ahmad has explained well.

4 parameters are important i.e Voltage , Frequency, phase sequence and phase angle

Phase is most important factor for the both machines and must be same otherwise it can cause damage to anyone of the machine. 

Good and well explained by Adnan Ahmad.