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Old 12-20-2008, 01:11 PM   #16
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Originally Posted by theatretch85 View Post
Search for "Phase Coupling", its done a lot with X10 systems in houses where there are multiple interfaces through out a house.


If you have an electric dryer outlet, this would be an easy install (also available in the 4pin variety as well)

Though you would probably need two to couple between all three phases.
Your first link kind-of confirms that a large incand. lamp will help transferring the 121 kHz between phases.

A 400v bipolar capacitor should also do it. 1 µF at 60 Hz is 2650 Ω but at 121 kHz it's 1 Ω.

10 ea. of these
CAT# RMF-104
in parallel, from
will set you back $3.50.

I don't know what current they can handle, though. Capacitors have a ripple current rating, related to the heating they can tolerate due to ESR.


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Old 12-20-2008, 03:21 PM   #17
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The capacitor's 400 volt rating means it can be put across lines with a 400 volt difference without burning out (actually less since you should have a safety factor built in). No problem connecting across two legs of a 3 phase household circuit, 208 volts. At 2650 ohms impedance for 60 Hz, it will draw about 80 milliamps or 16 watts.

Note that some capacitors, notably "electrolytic" capacitors, are meant for DC circuits. See the capacitor specs for the suitable kinds of power that the capacitor may be connected across.

You can design a "circuit" using coils and capacitors to bridge the phase legs that would have an even greater impedance at 60 Hz and still have a negligible impedance at the frequency used by your security equipment. The only disadvantage of the plain capacitor (let alone the incandescent lamp) is consumption of billable power.


The good conscientious technician or serviceperson will carry extra oils and lubricants in case the new pump did not come with oil or the oil was accidentally spilled, so the service call can be completed without an extra visit.

Last edited by AllanJ; 12-20-2008 at 03:36 PM.
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