Verifying proper synchronization of genset

[Hewlett]

I understand improper synchronization/ in particular too high phase angle can put generators and breakers under high stress, even tough there's no apparent problems during the regular breaker operations. Read a case story about damage long term, after "closing time" of breakers having been left out of the equations.
With respect to the automatic synchronization only; what do you consider "normal" requirements for design documentation and comissioning tests/ verification?

 

[GTstartup]

Most modern synchronizers have a feature that closes the breaker to be synchronized and times the close feedback. Divided by two, it gives an estimation of closing time. You could do the same thing with a high speed recorder.

To me this measurement comes under the heading "nice to have". I can't imagine that unless the breaker is EXTREMELY slow that it can make much difference. Especially considering the allowable phase angle tolerances while synchronizing.

 

[pwrengrds]

For commisioning testing I would expect a relay test set, or the generator supplying power to one side and test the various points that can be tested, while connected to a chart recorder to see if it provides a close signal at the proper times and does not when frequency and voltage is out of spec. Then it would be a matter of testing to see if it brings the voltage and frequency into spec before closing. The chart recorder would provide the documenation needed to prove operation.

 

[Hewlett]

Thanks for the responses.
GTstartup: A "smart" synchronizer, timing the closing feedback sounds interesting. Could you mention a make or model....could not seem to find one...
I found an article describing a similar problem, tough here with the general problem being mechanichal delay after "long inactivity" described here:

http://www.selinc.com/techpprs/6062.pdf

I'm looking at an Island configuration similar to a future one, with relatively irregular load...probable reason for the hz window being set quite large (0,4hz). I believe that with so large window, correct closing time may be a concern.
Found some older testsheets, which simply lists all synchronized breakers, with boxes filled with "OK" beside.
I would expect a bit more...some numbers at least...

I think it's reasonable to require switchboard/genset makers to define their limits, and at least require these measurements from some actual closure tests:
Phase angle
Delta U
RMS Current transient at closure.
What do you think? Would you require more?

 

[dpc]

Nearly all auto synchronizers allow for pre-set breaker closing time anticipation. Check Beckwith, Basler, etc.

The slow closing issue addressed in the SEL paper is interesting, but this type of protection has been rarely applied in the past.

Testing of synchronizing transients probably isn't going to do anything to deal with breaker slow closing issue - this is a malfunction, not a normal occurence.

It's somewhat rare that all components involved would be provided by one supplier (generator, governor, voltage regulator, synchronizer, generator breaker). If this is the case, you could specify synchronizing limits that they had to stay within for auto-synchronizing. But I've never seen it done.

 

[GTstartup]

Hewlett,

ABB Synchrotact Version 4 and 5 have the breaker timing feature. The synchronizer issues a command to the breaker (isolated of course)and the synchrotact stores the time from command issue to breaker close feedback (/2) in the breaker closing time anticipation parameter.