KVARH metering on 460V small motors

[jraef]

For the first time in my carrer, I have someone asking me for KVARH metering. I understand what KVAR is, and even KVAR Demand metering seems usefull, but I do not have any experience as to why someone would want to view reactive power cumulative consumption. What does this tell you? Is it something used in calculating operating efficiencies? I see it as one of the metering functions of a Mulilin 469 relay, but they don't even offer it on their lesser units such as the 369 or 269, so I can deduce from this that it is something typically associated with large motors. The real baffeling part then is that this request is for Qty 18 motors from 5-30HP @460V, and they want individual KVARH metering on each one!

Any ideas?

 

[jbartos]

Suggestions marked ///\\I understand what KVAR is, and even KVAR Demand metering seems usefull, but I do not have any experience as to why someone would want to view reactive power cumulative consumption.
///This is mostly the Utility and Power Generation issue related to wastes of energy. If you are not involved in those areas, you will probably not need it.\\ What does this tell you?
///How much of nonproductive energy is flowing in the power distribution system, being generated, causing wastes, etc.\\ Is it something used in calculating operating efficiencies?
///Yes, in some efficiencies, e.g. in the RI^2 losses being counted in efficiency relationships\\ I see it as one of the metering functions of a Mulilin 469 relay, but they don't even offer it on their lesser units such as the 369 or 269, so I can deduce from this that it is something typically associated with large motors. The real baffeling part then is that this request is for Qty 18 motors from 5-30HP @460V, and they want individual KVARH metering on each one!
///kVARh is a useful parameter to obtain other parameters, e.g. kVAh, etc. if required.\\

 

[aolalde]

Cumulative kVARH figures of motors will help to monitor the impact of reactive power consumption. The kVAR will increase the losses on the supply lines due to an increase in current demand, and will lower the operating Power Factor. With metered figures the user could decide when and were is the more effective location of corrective capacitor banks. A sophistication that not everybody can afford.

 

[jraef]

Thank you both. Very helpfull.

When I contacted them with this information and asked why they wanted this kind of metering on small motors, they peeled back the layers of engineering to discover that someone had meant kVAHR for kVolt-Ampere-Hours! (which probably should have been abbreviated kVAH)

Now it makes a little more sense, although in the process of asking it turns out that this was only intended for large motor specs anyway. It just goes to show that it is better to ask questions than blindly follow orders (military excepted).

Thanks again for the help and opportunity to learn. Once again I have had added to what my wife referrs to as my "fountain of useless information" (her description of my entire career).


"Venditori de oleum-vipera non vigere excordis populi"