Re: VAR

To: tesla-at-pupman-dot-com
Subject: Re: VAR
From: Richard Hull <hullr-at-whitlock-dot-com>
Date: Mon, 15 Jul 1996 11:39:09 -0700
Tesla List wrote:
> 
> >From pierson-at-msd26.enet.dec-dot-comSat Jul 13 22:05:03 1996
> Date: Sat, 13 Jul 96 17:52:49 EDT
> From: pierson-at-msd26.enet.dec-dot-com
> To: mail11:  ;
> Cc: pierson-at-msd26.enet.dec-dot-com
> Subject: VAR
> 
> >Richard Hull, TCBOR
> 
> >AC watts are volt-amps in a purely resistive AC circuit (like frying a
> >human being.)  But not in Tesla coil power circuitry.  the correct term
> >is VAR, volt-amps-reactive.
> 
> >This tells the listener that a simple current and voltage measurement was
> >taken in an AC circuit with known reactance present, but without a phase angle,
> >tells little more.
> 
>         Uhmmmmm.  That may be the way the term VAR is used in the Tesla Field.
>         Electrical engineers asign it a more specific meaning.  VAR is
>         DEFINED AS the '90 degree' value.  That is if a cap or inductor
>         (neglecting resistance) is thron on line it draws ONLY VARs.
>         (in fact, systemc ontrol boards have 'VAR meters' to aid in setting
>         up PF correction caps.  In fact PF correction banks are commonly rated
>         as '<mumble> VAR' banks.
> 
>         So with a complex load, there will be:
> 
>         WATTS == in phase power.
>         VA == Volts times amps == greater than WATTs
>         VAR == VOLTS times AMPS at 90 degrees (imaginary).
> 
>         WATTS being defined as tue power and VAR as 'imaginary' power, the
>         vector sum should match VA.
> 
>         ('imaginary' has a specific meaning in electrical engineering.  I
>         would guess most of the list members are familiar with this, but a
>         few may not be...)
> 
>         regards
>         dwp


You are correct!  Var is for purely reactive components and is at + or - 
90 degree phase angles.  I have used it rather loosely in my post and 
apologize to all.  Most Tesla circuits are inductive in reactance as 
appearing to the AC line and run a positive power factor angle.  A tesla 
circuit might be reduced to an equivalent pure inductance on the line  
rated in VARS and you would then need a capacitor of the same VAR rating 
to correct to zero phase angle or PFC.  Sorry about the lack of calrity.

Richard Hull, TCBOR