[b]GRADE A VS GRADE B VOLTAGE RANGE[/b] 1

[2banee]

I've heard the terms "Grade A Voltage Range" and "Grade B Voltage Range" used to differentiate between the fluctuations in voltage between what the utility delivers to the customer and what the range of voltage certain equipment can operate at. Typically a utility will provide plus or minus 5% of nominal voltage to the customer (grade A voltage range), but the equipment can withstand voltage fluctuations much greater than this (grade B voltage range).

Has anyone ever heard of this terminology and if so is this published somewhere with what those ranges actually are. Would this fall under NEMA, IEEE, or someone else? Could this have something to do with the CBEMA curve?

 

[dpc]

ANSI C84.1 is the basis for this requirement and has definition of the A and B ranges.

 

[busbar]

The current iteration of ANSI C84.1-1995 is published by NEMA and was reaffirmed in 2001. It is a terse document that seems to carry a lot of weight in the electrical-power world. [Do an online search to convince yourself if needed.] Like other consensus standards, it is the product of a committee—in this case—of utility and appliance-manufacturing representatives.

It covers roughly the 60Hz 100V-1200kV range. global.ihs.com is one vendor for paper/pdf versions.

 

[jbartos]

Suggestion: Visit

http://www.ece.nmsu.edu/~eump/ee494/3-11-04.ppt

etc. for more info

 

[busbar]

ARI Standard 110-2002 reflects some of the information in ANSI C84.1 for low-voltage systems and equipment.

https://ari.org/cgi-bin/bookstore/b...ction=display&details=std/individual/110.html

 

[jghrist]

The original posting has some confusion of terms. The difference between Range A and Range B in ANSI C84.1 is not "...to differentiate between the fluctuations in voltage between what the utility delivers to the customer and what the range of voltage certain equipment can operate at." The difference is that Range A is the normal voltage range and Range B allows limited excursions of voltage outside the Range A limits. Utilization voltage differs from the utility service voltage in both ranges. Range B utilitization voltage limits are the tolerance limits for equipment voltage.

 

[jbartos]

Comment: The posted terminology is not listed in IEEE Std 100-2000 Dictionary

 

[2banee]

Thanks for all of your comments. That is exactly what I was looking for. FYI, from a utilities perspective, I found the following information based on a Google seach.

http://www.utahpower.net/File/File22465.pdf

http://www.pge.com/docs/pdfs/news/l...tch/power_quality_notes/voltage_tolerance.pdf

and

http://www.pge.com/docs/pdfs/news/latest_topics/power_watch/power_quality_notes/understanding.pdf

 

[busbar]

C84 seems like a fine example of a “treaty”—a distillation of what may have been a lot of impassioned table pounding between utilities and appliance/equipment producers. For instance, it is open ended in significant features like refereence to time aspects in CBEMA/ITIC or acknowledged levels of waveform distortion like IEEE 519.

 

[jbartos]

Suggestion: The essential table from ANSI C84.1 appears in many publications, e.g. IEEE Std 100 Dictionary under Voltage Class.

 

[busbar]

Good point. Some of the C84 tables are in Chapter 3 IEEE Std 141-1993 [Red book]. Note the ARI standard is currently a free download.