Detuning Reactors |
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Detuning Reactors |
Nov 9 2007, 12:51 PM
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#1
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Junior Member ![]() ![]() Group: Members Posts: 3 Joined: 9-November 07 Member No.: 3,988 |
Greetings,
The the webpage http://www.lmphotonics.com/pwrfact.htm states: (under "Supply Harmonics") > Adding the inductance in series with the cpacitors will reduce their > effective capacitance at the supply frequency. Reducing the resonant > or tuned frequency will reduce the the effective capacitance further. (under "Detuning Reactors") > Using detuning reactors results in a lower KVAR, so the > capacitance will need to be increased for the same level of correction. I'm not convinced! Please consider the reasoning below. I have used 'w' to represent system frequency in radians per second. The detuned reactor is connected in series with the capacitors. The impedance of the reactor is: Zr = jwL The impedance of the capacitor is: Zc = 1/jwC = -j(1/wC) The total impedance of the reactor and capacitor is: Zt = jwL - j(1/wC) Note that the effect of adding the detuned reactor is to reduce the combined impedance, which in turn results a higher current. The current still "looks" purely capacitive, since (1/wC) is larger than wL. I conclude that: 1. Adding a detuned reactor makes the capacitor bank draw more capacitive current. 2. A higher capacitive current means a greater supply of reactive power. 3. The apparent kVAr is higher! Thanks, Submonkey |
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Nov 12 2007, 04:08 AM
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#2
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Posting Freak ![]() ![]() ![]() ![]() ![]() ![]() Group: Moderator Posts: 2,099 Joined: 24-April 02 From: Christchurch, New Zealand Member No.: 1 |
Hello submonkey
Welcome to the forum. Yes you are correct, the impedance is reduced and therefore the current is increased. This will of course increase the KVAR of the circuit. - I will correct the comment on the web page. Thank you for picking that up. No one else has seen this!! It is always a concern that no matter how often you read something, you can miss the obvious. Have a great day, Best regards, -------------------- Mark Empson administrator
Skype Contact = markempson | phone +64 274 363 067 LMPForum | LMP Tech Warehouse | L M Photonics Ltd | Empson family | Advanced Motor Control Ltd | LMP Software | Mark Empson Website |
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