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*To*: tesla@xxxxxxxxxx*Subject*: Re: Current Limiting and Impedence*From*: "Tesla list" <tesla@xxxxxxxxxx>*Date*: Tue, 26 Apr 2005 19:46:07 -0600*Delivered-to*: testla@pupman.com*Delivered-to*: tesla@pupman.com*Old-return-path*: <teslalist@twfpowerelectronics.com>*Resent-date*: Tue, 26 Apr 2005 19:46:31 -0600 (MDT)*Resent-from*: tesla@xxxxxxxxxx*Resent-message-id*: <WJBfOC.A.qfD.17ubCB@poodle>*Resent-sender*: tesla-request@xxxxxxxxxx

Original poster: "Paul B. Brodie" <pbbrodie@xxxxxxxxxxxxx>

It isn't confusing at all. I had completely forgotten that Z = sqrt(R^2 + X^2). That little reminder brought everything clear as can be. At least I can still adhere to Z total = Z1 + Z2 + ... Zn. Thank you very much for your explanation.

Paul

Think Positive

----- Original Message ----- From: "Tesla list" <<mailto:tesla@xxxxxxxxxx>tesla@xxxxxxxxxx> To: <<mailto:tesla@xxxxxxxxxx>tesla@xxxxxxxxxx> Sent: Tuesday, April 26, 2005 11:33 AM Subject: Re: Current Limiting and Impedence

>

> Hi Mark,

>

> This can be a confusing area.

>

> Series resistances add:

> Rtotal = R1 + R2

>

> For parallel resistances, the conductances (G) add:

> Gtotal = G1 + G2

>

> or expressed as resistance:

> 1/Rtotal = 1/R1 + 1/R2

>

> Now the tough part:

>

> Impedance, in the general case, has resistive (R) and reactive (X)

> components (sometimes refered to as the real and imaginary parts). For

> series impedances, the resistive components add up and the reactive

> components add up (keeping in mind that capacitive reactance is negative

> and inductive reactance is positive) so you get the following:

>

> Ztotal = Rtotal + jXtotal = Rtotal + j(XLtotal -XCtotal)

>

> You can't linearly add the resistive and reactive components together. The

> impedance is a complex number denoted by the j prescript on the reactive

> part. What you can do instead is determine the magnitude of the impedance

> using:

>

> Z = sqrt(R^2 + X^2)

>

> You can think of the R and X terms being two sides of a right angle

> triangle and the Z being the hypotenus (sp?). Series impedances add

> similar to resistances in that:

>

> Ztotal = Z1 + Z2

> but one needs to keep to the rules of complex math.

>

> Parallel impedances also behave similar to parallel resistances in that:

>

> 1/Ztotal = 1/Z1 + 1/Z2

> and again one needs to keep to the rules of complex math.

>

> Hope this helps more than being confusing.

>

> Gerry R

>

>>Original poster: "Mark Dunn" <<mailto:mdunn@xxxxxxxxxxxx>mdunn@xxxxxxxxxxxx>

>>

>>I still don't quite get it.

>>

>>1. Not that it matters for this question, but I thought I could sum

>>series impedence. Could you re-confirm? Are you sure you haven't

>>confused with Z^2 = R^2 + X^2? I don't mean to question and I am not

>>an expert so I am just making sure.

>>

>>If it is Z^2 then my formula for parallel Z must be wrong. I'm using

>>1/Z = 1/Z1 + 1/Z2 + ... . Just like resistance.

>

>

>

>

>

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