Synchronising and Load Sharing 
Megacon - the trendsetter in synchronisation control for paralelling or phasing of  AC supplies

Today Megacon uses the following two basic synchronisation control principles:

Bi-directional Check Synchronising Relay 

The system "S" guard is a low-differential Check Synchronising Relay.
Synchronising relay closes when phase differential is within set limits (sector "S") for a pre-set time ("t").
Sector synchronisation is the classical alternative for applications which allows that synchronisation accuracy and speed of synchronisation are interrelated.

Synchronisation accuracy (Df) can be calculated by following formula:
Df = (S : 360) / t (secs)
Example: Set phase angle (S) to 10 degrees and retention time (t) to 500mS to obtain an accuracy of Df:
(10/360) / 0,5 =  0,055Hz 

Uni-directional Fast and Accurate Synchronisation

The dynamically controlled system "P" provides the fastest "spot-on" synchronisation. Dynamic breaker closing time compensation assures precision 12 o’clock synchronisation, when frequency of incoming generator is slightly higher than busbar frequency.
Synchronising relay initiates generator breaker closure at moment "T", angle "a" is dynamically adjusted according the two systems frequency/phase differential.

This directional synchronisation relay allows operation when frequency of incomer is HIGHER than bus frequency. In this way incomer is protected against motoric operation during start-up.
To adapt the functionality of KSQ104F to any specific application, the direction of approach to synchronising  (LEAD, LAG or NEUTRAL) can be selected as required:
  • LEAD (incomer faster than bus)
  • LAG (incomer slower than bus)
  • NEUTRAL (bi-directional)
LEAD is generally the preferred mode. The synchronising relay will then operate when the frequency of the incomer is slightly HIGHER than the bus frequency. This is to avoid motoring of the incomer (entering reverse power condition) after the breaker is closed.
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