Sanguine
Joined: 20 May 2008
Posts: 2
Location: EAST COAST
|
 Posted:
Wed May 21, 2008 1:43 am Post subject:
How to find values for Total Reactance in a Circtut? |
|
|
Can anyone tell me how to find the Reactance in a circut (Para or Series)?
Need abit of help catching up on the Electronics Worksheets my teacher gives me and this one has been troubling me for awhile now. Any help would be greatly appreciated 
_________________
"We shall go on to the end, we shall fight in France, we shall fight on the seas and oceans, we shall fight with growing confidence and growing strength in the air, we shall defend our Island, whatever the cost may be"~Winstin Churchill |
|
Electrofix
Joined: 01 Jan 2008
Posts: 5
Location: Worcesterhire, UK
|
| Posted:
Mon May 26, 2008 10:03 pm Post subject:
Reactance calculations. |
|
|
Reactance comes in two 'flavours': capacitive and inductive. Reactance is measured in ohms *. The value of the reactance of a component is dependant on the frequency of the current passing through it or the voltage appearing across it.
For a coil - inductive reactance: X = 2*pi*f*L
For a capacitor - capacitive reactance: X = 1/(2*pi*f*C)
where f = freq. in Hz, pi = 3.142 . . . C = Farads, L = Henries
Inductive reactance is a positive quantity; capacitive reactance is a negative quantity.
In a series cct. (a) add all the inductive reactances together arithmetically. Ditto (b) the capacitive reactances. Then the total reactance in the series cct. is (a) minus (b). You may get a negative result - which tells you that the net reactance is capacitive.
In a parallel cct, add the reactances together according to the reciprocal law:
1/Xnet = 1/X1 + 1/X2 + 1/X3 . . . . remembering that capacitive reactances take a minus sign.
If you have a network of series reactances (L and C) in parallel with other series branches of series reactances (L and C), reduce all the series branches to one resultant reactance per branch, then treat these as seperate parallel reactances as above to find the resultant net reactance.
* Reactance is measured in ohms.
Personally, I find this accepted nomenclature disappointing for reactance. It leads to confusion with "real" ohms - that you find in d.c. A term such as Xohms would be more helpful when dealing with reactance. Ditto impedance: Zohms would be more enlightening.
HTH
Electrofix.
_________________
If an electrolytic cap. explodes and there is no one there - does it make a sound? |
|
FAQ
Memberlist
Register
Profile
Log in to check your private messages
Log in
