What is the need of synchorization system between the stand-by generators?

frequency and voltages are most important thing for synchronization

The need of synchronization for standby Generators is to be able to operate them on-line and in parallel with existing energized bus or other Genarators already operating on-line. Its needs to adhere to requirements of synchronization or to On-line in parallel with energized system.

synchronization is the process of matching the speed and frequency of a generator or other source to a running network. An AC generator cannot deliver power to an electrical grid unless it is running at the same frequency as the network. If two segments of a grid are disconnected, they cannot exchange AC power again until they are brought back into exact synchronization.

There are five conditions that must be met before the synchronization process takes place. The source (generator or sub-network) must have equal line voltage , frequency , phace sequence , phase angle and waveform to that of the system to which it is being synchronized.

Although, all ready given answers are somewhat correct.

But to further elaborate these answers, Please note that Multiphase or Single Phase AC Generators are usually Designed to Output a Sine Wave of say600 /400 /220 Volts of50 /60 Hz.

Generators / Electrical AC Source Synchronization means Matching One Source Sine Wave/s with other Source/s Sine Waves witch Following Parameters:

No. of Phases,

Sequence of Phase Rotation

Amplitude of Phases,

Phase angle,

Frequency.

If not matched, you can easily understand that any Source Parameter Difference Can affect the Outputs, which may damage the Load, Distribution System or even the Generators / Source.

For Example:-

Out of Phase Voltages may totally cancel each other, with a resultant no Voltage at Outputs. Or Sumup each other to double the the Resultant Voltage at outputs.

1. If the voltage is not synchronized. the new generator behaves as a motor.2nd generator is useless here as it will cause a voltage drop

2. If the phase is not synchronized, Circulating currents(synchronizing current) will flow through the closed systems of the two gen sets. losses

3. If the frequency is not synchronized, the resultant voltage will be low (think wave addition)

4. if wave form is diffrent, resultant votage will be low

5. phase sequence is diffrent, no or riddiculous op resultant voltage.

I think it is required to enable engagin the standby generator to the operating network safely without damaging the standby generator or causing fluctuations in the load.  

synchronization is the process of matching the speed and frequency of a generator or other source to a running network. An AC generator cannot deliver power to an electrical grid unless it is running at the same frequency as the network. If two segments of a grid are disconnected, they cannot exchange AC power again until they are brought back into exact synchronization.in another short define means Matching One Source Sine Wave/s with other Source/s Sine Waves

As we all know to check on  synchronisation:-

1) VOLTAGE MATCHING BETWEEN INCOMING-BUS (TG PT INCOMING SUPPLY) & RUNNING BUS     ( GRID) / ANY OTHER TG  PT SUPPLY) VOLTAGE MATCH           =    2%.

2) FREQUENCY MATCHING BETWEEN INCOMING ALTERNATOR FREQUENCY WITH GRID FREQUENCY OR OTHER TG  FREQUENCY MATCH          =0.1 % .

3)PHASE SEQUENCE MATCHING ALONG WITH PHASE-ANGLE       =5-7 DEGREE.

4) INCOMING TG VOLTAGE,FREQUENCY SHOULD BE SLIGHTLY HIGHER THAN RUNNING TG/GRID.........CONSIDERING CONDITION  1),2,3.

START SYNCHRONISATION:-

(a) SELECT INCOMING & RUNNING BUS.

(b) SELECT LIVE MODE.

(c) SELECT FINE.

(d) SELECT SYNCHRONOCOPE ON.

NOW DOUBLE-VOLT-METER & DOUBLE-FREQUENCY-METER WILL COMES LIVE & BULB START GLOW. 

SYNCHRONOSCOPE WILL ROTATE  SLOWLY IN CLOCKWISE DIRECTION, WHEN IT COMES & HOLD(VERY SLOW MOVES CLOCKWISE) IN12-O-CLOCK POSITION SYNCHRONISING PERMISSION TGS WILL BE SYNCHRONISED IF IT IS IN AUTO-MODE/MANUALLY BY CLOSING TG-BREAKER.

NEED OF SYNCHRONISATION:-

(a) PARALLEL OPERATION.

(b) LOAD SHARING.

(c) LOAD TRANSFER.

(d) STABILITY.

NOTE:- BUT WRONG SYNCHRONISATION MAY IMPOSE HEAVY TORQUE IN ROTOR/FETAL DAMAGES IN OTHER AREAS.  OR BOTH TG TRIPPS, BECAUSE THOSE HAVE HIGHER CAPACITY WILL TAKE  LOAD FROM2ND-TG/STANSBY TG, SO1ST ONE BECOMES OVERLOADED TRIPPS IN OVERCURRENT/UNDERVOLTAGE &2ND ONE TRIPPS IN UNDER/REVERSE POWER OR ANY OTHER REASONS.

FOR THAT WE NEED FAST & ACCURATE RESPONSE FROM AVR(AUTOMATIC VOLTAGE REGULATOR) , TSP( TURBO SUPERVISORY PANEL), METERING-SYNCHRONISING PANEL,GENERATOR PROTECTION PANEL, LAPT,NGR & ALL OTHER INTERLOCKING/PROTECTION IN LOGICS.

NOW-A-DAYS EGCP(ELECTRONICS GOVORNOR PANELS) ,DSLC & MSLC ( DIGITAL & MASTER SYNCHRONISING PANEL WITH PROPER APPLICATIONS & SETTINGS) ARE EXTENSIVELY USED FOR SMOOTH SYNCHRONISING- LOAD-SHARING-LOADSHEDDING APPLICATIONS.THOSE PANELS  COMMUNICATES ALL BREAKER ON/OFF FEEDBACK & COMMANDS ALONGWITH CT-PT-MW-MVA-MVAR TRANSDUCERS INPUT/OUTPUTS AS REFERENCE/COMMUNICATIONS.

Same the sequence for both generators  

Same the V.R.M.S for both generators  

Phase angle between them is zero ,

.Same the Frequency for both generators  

voltage and frequency