[Fairhope1]

Dear Sir or Madam,

My church's bells are rung by three separate Rabbit 2000 Embedded Processors. The combined wattage output of the processors, when not activating solenoids to ring the bells, is only six watts. Two of the bells are rung with a single solenoid which, at activation, draws a peak current of 250 watts. The big bell uses two solenoids which has a peak current of 500 watts. The activation periods for the solenoids is between 60 and 90 milliseconds. The only situation in which more than one bell is rung at the same time is when regular AC current is available and then manually by pushing a button. Lately, our town has had a slew of power outages. During the last outage, one of the processor's flash drives was corrupted (i.e. power surges, other current irregularities). We will have the system designer reload the program and plan on purchasing a good surge protector designed for electronics. As a result of the outages, we are considering the purchase of an UPS that is rated at 1500 VA and 900 watts. THE BIG QUESTION: Will a traditional UPS system recognize the peak currents (i.e when a bell rings) as an inductive load and deem it as an overload or will it handle the peaks as they involve a wattage that is well within the wattage specifications? One technician said an inverter type UPS would be more appropriate as it would handle all three bells at the same time. That same tech, however, didn't flat out say the standard UPS wouldn't work. Any input on this matter would be greatly appreciated! Sincerely, Steve

[Scleros]

Have to ask - do you really need to ring the bells when the power is out?

If not, size the UPS to protect the Rabbit control system only. Otherwise contact application support of your chosen UPS vendor and ask for a recommendation. One problem you will encounter when the typical load (Rabbit) is so tiny compared to the UPS capacity (which you are sizing for the relatively infrequent bell ringing) is the periodic battery self tests will pass even when the battery needs to be replaced. The UPS will not alert you for battery replacement and then when you need it, the battery will be dead. You can work around this by running a manual self test periodically with a suitably sized load attached, but that's just hassle.