Description
The digitally controlled KCQ331x2 provides visual presentation of relative speed and output signal necessary to permit check synchronising between two systems.


The synchronising relay will close when the incomer (generator, busbar, etc.) voltage and phase angle have been within the limits during the set retention time.

A green lamp (CB close) indicates the close command to the breaker.

There is lamp indication for reference source present (BUS PWR) and incomer status (GEN PWR).

A green lamp (VOLT OK) is lit when both voltages are within the set limits.

Applications
The KCQ331x2 can be used for both single and three phase systems. Any two phases (or phase-neutral) can be used for synchronising as long as they are the same two phases on both sides of the breaker.

The unit is meant for manual and semi-automatic synchronising only. There is no compensation for the breaker closing time.

For automatic synchronising the KCQ104x2 "SPOT ON" principle should be used to obtain compensation for breaker closing delay.

User settable limits and retention time on the front of the unit.

The analogue -10/0/+10mA output signal can be used as speed reference to a generator controller, with polarity and amplitude proportional to frequency difference between the two systems.

System status:
KCQ331x2 is fitted with a system status relay. As standard the unit is powered from generator side (terminal 3 & 4), when power is ok and unit is working correctly the relay activates. It will release on alarm or when unit is not powered. Separate auxiliary supply is needed for continuously system status.

Normal operation                : Closed contact
Alarm condition/unpowered  : Open contact

System "S" the sector synchronising principle
The KCQ331x2 is a low differential bi-directional check synchronising relay.

The synchronising relay closes when the incomer (generator, busbar, etc.) frequency is close enough (diff 0,018 - 0,83Hz) to stay within the phase angle sector (S) for the set retention period (t).

Sector synchronisation is the classic alternative for applications which allow synchronisation accuracy and duration of synchronisation process to be interrelated. There is no compensation for the breaker closing time.

Approximate synchronisation accuracy relative to 12 o’clock position (Df) can be calculated by the 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

If the phase angle limit is set too low and retention time too high for very low differential synchronising, it can be difficult to achieve synchronisation. If there is a continuously fluctuating load between the two systems (for example to synchronise against a shaft generator when a vessel is in rough weather), the KCQ104x2 "SPOT-ON" principle is more suitable.

The "phase angle" setting on the front of the unit refers to the total phase angle sector (S), centred about 0°. Hence a setting of 10° means the sector spanning from -5° to +5°.