I bought UPS'es for some of my machines, and discovered a nice additional functionality that my application provides.
Initially watchcondition of the form:
<watch condition="BatteryPower" action="Stop" />
was written for use with laptops CPU or cudamining mining scrypt.
I discovered that when I connected a UPS to my PC using USB, then stationary PC started showing battery status and by extension responding to the above event when UPS switches over to battery power. Nice! I can now also reduce power consumption of those power-hungry scrypt-mining GPUs when there's a power failure.