Subject: Re: [eman] Terminology: power

From: "John Parello (jparello)" <[email-masked]>
Date: Thu, 15 Sep 2011 13:38:03 -0700

ACK

IEEE 100 

Jp

From: [email-masked] [mailto:[email-masked]] On Behalf Of
Juergen Quittek
Sent: Tuesday, July 26, 2011 4:26 PM
To: eman mailing list
Subject: [eman] Terminology: power

Hi John,

In draft-parello-eman-definitions-00 you define power as:

	     Power 

	       Power is a rate of energy conversion.  As the unit of
time 

	       approaches zero a power measurement is called an
instantaneous 

	       power reading.  Typically when implementing Power
monitoring in 

	       hardware, a measuring device may have to compute an
average 

	       value per some unit of time to express a reading to
approximate 

	       an instantaneous power measurement.  

	       Example: 

	       Reference: 

	       Derived from [ISO50001] 

This contradicts the definition of instantaneous power in the IEEE
dictionary of standards terms where active power is "The time average of
the instantaneous power over one period of the wave." This implies that
the instantaneous power changes from zero to a maximum and back two
times of a period, i.e. 100 or 120 times a second for common AC power.
Typical meter implementations measure power over at least half a period.
The result of their approximation is not called instantaneous power. It
is the power over a (short) interval of time.

Again, I propose taking text from the IEE dictionary or a similar
source.

    Juergen