MOV or no MOV?

[BossNoodleKaboodle]

Does APC use MOV's in their SmartUPS to supress surges? If so, do these MOV's account for its AVR functions? If not, how do they work exactly?

 

[Ice Czar]

what I dont know is the typical surge suppression scheme of a common SPS
but Im now looking for it

AC input -> fuse -> MOVs connected across input -> line filter -> rectifier -> ....

MOV's are "metal oxide varistors" - they're sort of like a zener diode, but bidirectional. They act as an open circuit across the AC line until the voltage reaches a certain point, then when that happens they basically short out the line. So If a power surge occurs, the MOVs will conduct at the higher surge voltage and blow the fuse.

"Surge supressor" power bars just contain a bunch of MOVs. Decent ones have a circuit breaker before the MOVs which will trip with the high current, but cheap ones just rely on your house's circuit breaker to trip.

There's no super-extra-high-advanced technology inside Monster power strips or anything. This stuff has been around since the 60's.

according to our EE

 

[aug1516]

according to our EE

Good info but doesn't really answer the question. A UPS is quite a bit different than a Monster brand surge supressor. I thought UPS's use something else to protect against surges but I may be mistaken.

 

[Ice Czar]

SPS = Line Interactive UPS

technically they are Standby Power Sytems not Online Uniterruptable Power Systems

the difference is typically that when its on the mains, it uses MOV tech for surge suppression
(or at least most do) but when its on the battery the power is isolated from the mains and drawn from the batteries throught the inverter and to the PSU like an online UPS does all the time and surges from the mains are impossible, the battery chargers fuse would blow, and evenm if it didnt the batteries are a buffer