I have just followed testing for new circuit breaker dummy and auto sync testing.

The adaptive control was disabled for the test and a setting of 70ms was set in CB1CloseTime and CB1CloseTime.

The testing was successful and the 52G measured closing time was recorded for both units at around 260ms.

Can anyone advise on what nominal setting this closing time would require for re-enabling the adaptive control to allow for a margin of control and prevent nuisance diagnostics?

 

I've been hoping someone else would respond, because my response to a 260 msec closing time is: WOW! That's more than a quarter of a second, which for a 50 Hz system is about 12.5 cycles, and for a 60 Hz system about 15 cycles. That just seems very slow. I'm much more accustomed to seeing breaker close times on the order of four or five cycles, sometimes six or seven cycles.

70 msec really seems like a more typical expected breaker close time--for a 50 Hz system that would be approximately 2.5 cycles, for a 60 Hz system that would be a little more than 4 cycles--both reasonable expectations for the commonly-used generator breaker closing mechanisms.

The breaker self-adapt corrective function will automatically monitor the difference in time (cycles) between when the breaker close command is "sent" and when the breaker actually closes. The breaker status/feedback is supposed to be from a properly-adujusted direct-acting contact from a set of auxiliary contacts physically mounted ON the breaker mechanism so that the signal is very accurate and reflective of the actual time the breaker requires to close.

AND, the breaker self-adapt corrective feature is supposed to only be used on stored-energy type breaker closing mechanisms (charged springs; pneumatic operators; etc.). Some older style breakers have large solenoids which close the main contacts of the breaker--and those are very slow with respect to stored-energy type breaker mechanisms.

Setting up the self-adapt corrective feature for stored-energy mechanisms with status/feedback from the breaker usually means setting the starting point for the feature to the tested- or manufacturer's rated closing time, and then setting the limits of adjustment, after which Diagnostic Alarms will be annunciated.

But, a 260 msec closing time implies either the breaker does not have a stored-energy mechanism, or the status/feedback is not properly adjusted, or the status/feedback comes from an auxiliary relay or a mechanically-operated set of contacts not physically mounted on the generator breaker. (I once saw a flimsy rod which had to be manually connected to the breaker after it was racked-in that was moved by the breaker mechanism to operate a relay on the side of the breaker cubicle. The flimsy rod was bent and would actually flex when being actuated--and the signal coming back from the relay was WAY wrong.)

My recollection is that the feature will make a one-cycle adjustment on the next breaker closure if needed, up to the limit set in the configuration. The limit would be set per the breaker manufacturer's recommendation for service periods, as if the limit was achieved that would likely mean the breaker is taking too long to close and needs maintenance. That's what the "breaker close time out of limits" really means--the breaker needs maintenance. That's if the limit is properly set, and the status/feedback comes from a proper- and properly-adjusted set of status contacts, AND if the breaker uses a stored-energy type of operating mechanism.

But, still--260 msec seems unusual for a stored-energy mechanism, or that the status is not coming from a properly-adjusted direct-acting contact physically mounted on the breaker. If, in fact, the breaker actually does take a quarter of a second that would mean the close signal would have to be sent a quarter of a revolution of the synchroscope before the 12 o'clock position--that just seems excessive.

 

CSA

Thanks for getting back. Maybe I am reading the closed time wrong.

On the PTUR tab for "Var_sync" the LIVE VALUE is labelled 0 mSEC and the recorded value for the I/O LIVE VALUE CB1CloseTime was 0.261. Could I be reading the scale wrong then and the actual value is actually 26.1ms?

This was a new breaker installation with a 60Hz cycle.

During the test the setting was adjusted from 83.3 to 70ms and the adaptive time "disabled". If the 26.1ms closing time is more likely then would 70ms be acceptable to retain as the final setting.

thanks
Topcat

 

Topcat123,

I don't have access to a Mark VIe project file at this time, so I can't look at the PTUR configuration, but I would surmise there is some kind of 'Help' for the fields which might have some detail about the units and the scaling of the field's value.

If it's really seconds (0.261 seconds, or 261 msec), and it's the time difference between when the 25 contact closes and the feedback contact changes state I would have to think there's something amiss with the feedback to the PTUR--it's either coming from a relay or the direct-acting contact being used for the feedback to the PTUR is not adjusted properly. That's just a pretty big number.

If the self-adaptive feature was disabled, it shouldn't matter what's in the field. I would think.... I do recall early versions of Mark VIe had a "bug" in the firmware that wouldn't allow the Diagnostic Alarm of the self-adaptive feature to be disabled when the self-adaptive feature was disabled (the firmware kept looking for a signal even when the feature was turned off and would annunciate 'breaker close time slow' alarms). I thought that was fixed; there was a work-around for that--but I've forgotten what it was.... It's been too long; sorry.

If the rated breaker close time was 70 msec, then a self-adaptive limit of 83.3 msec would seem to be a good number (what is that--about a 20% difference?). Actually, some (but not all) breaker manufacturers publish breaker close time values that would indicate a potential problem requiring maintenance (say, 83.3 msec for a breaker with a rated close time of 60-70 msec--these values are just examples!!!). It would be a good idea to try to find the limit above which the breaker manufacturer recommends maintenance and use that for the limit value. Again, it's my understanding that the purpose of the alarm is indicate a breaker mechanism that is taking too long to close, indicating a possible maintenance issue is developing or has developed.