I never knew an AVR could actually break, not until it happened to me.
I have two AVRs protecting my server setup. One is an American brand, relay type, and it's not even two years old. The other is a Secure brand AVR, green colored, servo motor type, about five years old. I figured the old one was the unreliable one, mainly because it had this static noise, almost like an ungrounded microphone, whenever it was connected to my power station. That noise made me trust it less, so I moved it outside to handle the fridge and the TV instead, and let the newer relay AVR take over the server duties.
Looking back, there was already a warning sign I brushed off. Days before all this, I got electrocuted by that same relay AVR. At the time I didn't think much of it, just wrote it off as one of those things. I didn't realize it was the first sign that something inside it was already going wrong.
If I hadn't bought a power station, a BLUETTI Elite 30 V2, I probably wouldn't have caught the rest of it in time.
A quiet start to a chaotic day
There was a power outage that morning, from 10AM to 2PM. Nothing unusual there, outages happen. I ended up sleeping through most of the afternoon, up until around 5PM.
When I woke up and started checking on things, that's when I noticed something was off. By 6PM, I realized my power station was not charging at all.
The strange back and forth
I was already testing a TP-Link Tapo P110 smart plug I'd bought, since I wanted to measure the total power consumption of my PC setup. The moment I plugged the power station in through the Tapo, it stopped charging and threw a warning: over 113% overvoltage.
I had no idea why. I unplugged the Tapo, and things went back to normal. I plugged it back in, and the problem came back. It felt like the back and forth would never end, and I genuinely started wondering if the smart plug itself was defective. I even tested a second Tapo P110 I already had, to rule out a defective unit. Same problem, on both plugs.
The real culprit
Tired of chasing ghosts, I finally tested the old Secure AVR again, static noise and all. It worked completely fine, powering the station without any of the overvoltage warnings.
That's when it clicked. The relay AVR, the one I trusted more because it was newer and quieter, was the one that had actually failed. And thinking back to that electric shock days earlier, it all started making sense. Here's what likely happened. Our power provider, MECO and VECO, had been sending undervoltage, below 191V, possibly tied to the outage earlier that day. The relay AVR kept trying to compensate for that, and in the process, the relay contacts welded themselves together in the "boost" position. Once that happens, the AVR gets stuck permanently boosting the voltage, which is exactly why it was pushing out around 260V. It had likely been failing internally for days, and it had been overvolting for hours on this particular day without me realizing it, while I slept through the afternoon.
At some point I noticed a plasticky, almost metallic burning smell coming from my desk, where the whole setup sits. That was the moment I knew something was seriously wrong.
I immediately unplugged the relay AVR and swapped back in the old Secure servo motor unit, static noise and all. Then I went out and bought a replacement right away, a Fujidenzo unit at roughly the same price as the American relay one.
I never expected a relay type AVR to fail like that. Now I know it can happen when the incoming voltage is constantly low and the AVR is forced to compensate nonstop. And it turns out, a little static noise from a servo motor AVR doesn't actually mean it's unreliable. It just means it's, well, a servo motor AVR.
One more scare
After all that, my Unraid server didn't turn on right away. For a moment I genuinely thought I might have lost everything on it. It did eventually power up fine. Turns out the magic packet just didn't fire correctly, nothing to do with the AVR incident at all.
What I'm taking away from this
- A relay type AVR isn't automatically better than an older servo motor one, especially under sustained undervoltage conditions.
- Static noise from a servo motor AVR isn't necessarily a sign of failure. Silence from a relay AVR isn't necessarily a sign of health.
- Getting shocked by equipment is never nothing. If it happens, unplug and test it properly instead of shrugging it off.
- A smart plug with power monitoring, like the Tapo P110, can be an early warning system, not just a nice-to-have.
- Trust your nose. A burning smell near your equipment is never something to explain away.
- Having a backup AVR on hand, even a noisy old one, saved my desk that day.
Damn, what a day. I thought I lost it all.