# Re: RMS

```Subject:
Re: RMS
Date:
Tue, 8 Apr 1997 19:39:23 -0400 (EDT)
From:
richard hull <rhull-at-richmond.infi-dot-net>
To:
Tesla List <tesla-at-pupman-dot-com>

At 05:26 PM 4/7/97 -0500, you wrote:
>Subject:
>        RMS
>  Date:
>        Mon, 7 Apr 1997 16:33:29 -0400 (EDT)
>  From:
>        SSNSanders-at-aol-dot-com
>    To:
>        Tesla-at-pupman-dot-com
>
>
>I need to know about RMS of my xformer when calculating the capacitor
>value
>needed. What is the RMS and how do I find it?

Root Mean Square or RMS can refer to voltage, current, power, etc.
Soince
you stated you needed to know this for capacitor purposes I'll assume
you
are talking about RMS voltage.  This is actually the name plate
voltage.  It
is the voltage measured by most common AC voltmeters for a sine wave.
The
peak voltage is important for the capacitor stress purposes.  It is
1.414
times the RMS voltage.  A 10Kv (RMS) oil burner transformer would have a
peak voltage of 14,140 volts appear on the cap.  However, with worst
case
ideal conditions, twice that value must be allowed for.  With inductive
kickback and other no-no's I usually head for a DC rating on the cap of
three times the RMS value of the voltage input.  R. Hull, TCBOR

Also volt amps is
>something I
>need to know about and Ive put it off long enough, or as long as I can.

Volt amps are what in a DC circuit would be called power. (volts X
amps)  In
an AC circuit, due to varying reactances about the circuit and the
resulting
power factor upset, Volt amps  (VA) are used to substitue for a sort of
power indication with the realization that the power factor is not
unity.

Richard Hull, TCBOR

>I am
>starting to get into more serious coiling and I am going to go for Q and
>preformance so I guess Ill have to do some stinking math.    Stephen
>Sanders
>
>

```