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Re: Calculating Voltage Loss


As the cable and the active devices heat up during the day, so does voltage drop.
Your actives start to draw more current, and the cable becomes more resistant to the flow of electrons as the conductors get hotter.

You can still have a load that is within spec for the power supply's output, but still have undervoltage at distant actives because of the loop resistance of the cable.  

I would establish exactly what actives are fed from this power supply, check the load at the peak of the day when you are having problems.
If it exceeds 80% load, you might consider bumping up the voltage setting of the power supply in order to bring the load into the nominal load rating if possible.   Of course, you have to consider what your power inserter's rating is.   You typically don't want greater than 12 amps of load at 90 vac passing thru the inserter or it tends to start melting the contacts in the faceplate, or the plastic seizure mechanism holder.  If you have too much load, make sure that legs not needing AC are unpowered as mentioned in previous posts, but if your load is too high for a 90 VAC power supply, you will definitely have to either add a new power supply, or if you have a neighboring power supply that has some loading to spare, then shift some of the load to that power supply, but don't overload that one either.

If your load doesn't exceed your power supply's nominal load rating, I would suggest you relocate the power supply to a more central location relative to the actives that power supply feeds.   Your problem is probably that you have a power source that is too distant to overcome the voltage drop of a long length of cable itself as well as all the other actives that derive their power from the same coaxial feed, which causes inadequate voltage for the power packs in your actives to operate.

I would definitely make sure that the undervoltage selectors in your actives are set appropriately as mentioned in previous posts.

Hopefully this helps in some way,

Jeff
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Posted in reply to: Calculating Voltage Loss by Sweep R US
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Re: Calculating Voltage Loss Sweep R US 6/9/2011 5:37:02 PM