PFC points to BMS

[masalah]

Dear all,

The BMS (Building Management System) monitors all pieces of equipment within the project. A submittal for the BMS mentions that the points taken from the PFC (Power Factor Correction) is only one point "general fault". Is this correct & sufficient.

Thank you.

 

[itsmoked]

If I understand your rather sketchy question I'd say NO, just monitoring the PFC for a "general fault" is not sufficient.

The entire point of the PFC system is to maintain a specific Power Factor. It makes sense the BMS would want to know WHAT the power factor is at any moment. This could be critical to managing the facility's power costs.

Keith Cress
kcress -

http://www.flaminsystems.com

 

[masalah]

Thank you Keith.

And so?? What will be the points that shall be connected to the BMS system??

Current through an ammeter? Voltage through a voltmeter?
Or a single point from a differential relay for example that subtracts vectorially both angles to calculate the power factor??

i.e. how is that P.F. as an output from the PFC (capacitor bank) can be calculated?

 

[sibeen]

Surely the PF of the site would be taken from metering on the main switchboard. If that's the case I see no reason to have anything but a general fault come from the PFC unit.

 

[crshears]

Masalah,

I'm not entirely sure either what's being asked in the OP...but I'll weigh in anyway.

IF the Building Management System provides only a general overview of the various services within the structure, and IF the term 'General Fault' is simply the text of the generic alarm that shows up at the monitoring site, and IF it is made clear that the responsibility of the attendant is to notify the on-call electrician of this alarm so further investigation can be undertaken, THEN the specification could be correct and sufficient...it looks like you have some spadework ahead of you.

The choice to monitor and / or control the power factor of a building's electrical supply is usually made by the owner or investors. The electrical design engineer figures out and recommends how best to do this, employing his or her qualifications, training and experience.

More spadework...

CR

 

[waross]

If you have a power factor controller, it should do an adequate job of correcting the power factor. The availability of a "PFC general fault" alarm suggests that there is a power factor controller. With a power factor controller there is no need for the BMS system to concern itself about the actual power factor as long as the PF controller will send an alarm signal if it is unable to correct the power factor.

Bill
--------------------
"Why not the best?"
Jimmy Carter

 

[jraef]

I agree. A PFC system has no tangible effect on anything other than power factor, so what would the BMS do about seeing it change? Shed only inductive loads? That's pretty much everything a BMS has control of anyway, so would one opt to sacrifice the comfort of the occupants in favor of not getting a PF penalty? If so, a general alarm saying that the PFC controller has failed would be sufficient to enact whatever draconian choices need to be made.

"Uh oh, the PFC is down. Save the Engineers, cook the Accountants..." (assuming here that it would be us Engineers who would program the BMS)

"Will work for (the memory of) salami"

 

[masalah]

Thank you all, really I got great benefit from the info you declared.