KSQ331x2 Series
  • Low differential check synchronising, sector principle
  • Bi-directional synchronising
  • Manual and semi-automatic synchroniser
  • Integral voltage differential protection
  • "Easy view" status presentation
  • Generator speed reference (analogue output)
  • Systemstatus output
The digitally controlled KSQ331x2 provides both visual presentation of relative speed and phase angle relationship, and output signal necessary to permit check synchronising between two systems.

KSQ331E2 is the standard and it takes the auxiliary voltage from the monitored voltage on terminal 3 & 4.
KSQ331G2 have separate auxiliary supply on terminal 19 & 20.

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.

KSQ331x2 can be used both for single and three phase systems. Any two phases (or phase-neutral) can be used for synchronising as long as it is the same two phases on both side 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 KSQ104x2 "SPOT ON" principle should be used to obtain compensation for breaker closing delay.

User setable limits and retention time on the rear.

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:
KSQ331x2 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 KSQ331x2 is a low differential bi-directional check synchronising relay.

The synchronising relay closes when the incomer (generator, busbar, etc.) frequency is close enough (diff 0,01 - 0,5Hz) 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.
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