Odd Behavior w/ Minoston Plugs?

Other Devices & Integrations Lighting & Load Control
#1

I have a few Minoston MP21Z and MP21ZP plugs that I’ve been using without any issues until recently.

The only difference between the two plugs is that the “ZP” model has a power meter to monitor electrical draw through the plug. I haven’t encountered any issues with the “Z” plugs to date.

I recently shut down my electricity-hungry home lab setup and moved workloads over to a few Intel NUC devices and a fanless firewall appliance. In the process, I’ve reduced my electrical draw from about 700W continuous to about 30W continuous. Two of the NUC devices that I am using are NUC5 boxes and I have them plugged into the “ZP” plugs. One has been running just fine, but the other has been acting odd.

I power on the plug (which automatically powers on the NUC). The device boots up and runs normally for anywhere from about 24-36 hours and draws 7-8W max at any point. Then, the plug encounters some sort of issue and goes into a sort of “tripped” state where the light on the side flashes slow and you have to unplug it and plug it back in to get it to operate again.

I contacted Minoston to inquire about troubleshooting (or maybe even adjusting settings) and then simply said “we’ll send you a new one.” Great. But… in the meantime, I swapped it for another new (fresh out of the box) “ZP” plug and it did the same thing.

I’m basically wondering if anyone has any experience with these plugs specifically, or maybe ones that are materially similar. These are rated for 15A/1875W of resistive or general purpose load, and 5A/625W load for a tungsten filament type of draw. The actual draw I am seeing on these is less than 1/10 of an amp (.1A), but the load is an AC->DC power converter “brick” (like a laptop power supply, if you will).

The “Z” plugs are rated at 10A resistive load capacity.

Anyone have any thoughts?

#2

I have several of Minoston’s on both my Ezlo and Vera Plus networks. I don’t find them unreliable but my applications are table lamps and other more mundane HA tasks.

I am 99% sure these devices are relay contacts for switching the load (vs electronic switch like a triac). As such they should be less bothered by load but the line side of any switched mode power supply is highly capacitive so upon connection (or in this case upon turn on) there can be a very high current inrush. That might damage the relay contacts over time. If your load is truly 8W max then I doubt the inrush would be an issue though.

If possible look for a logic level input to control the power supply into/outof sleep mode. You could control from a dry contact ZWave device to enable or disable the power supply. Being logic level you wouldn’t have the current surge issues and the power supply probably has some soft start (gradual ramp up) logic in it. Not sure you have access to the SMPS’s innards, but this might be a cleaner work around.

#3

Good thoughts, not sure how directly they may apply for me, though.

The specific plug I had issues with has been “replaced” by Minoston. The original one was labeled “V2.0” and had a date listed of 0222. The replacement device has no version number stamped on it and the date code days 0722. Also, the switch on the side is more of a contact relay as opposed to a press button sort of device (I suspect that the inner workings a basically the same but the contact device is different). Since there is no protruding button, the overall dimension is just slightly narrower across than the one it replaced.

I had a similar incident occur once (so far) with an identically labeled plug controlling the same NUC device. I swapped the power block and then the NUC itself to see if I could further narrow down the culprit. Replacing the power brick made no difference, but replacing the NUC itself with a different one has not (yet) resulted in an error in the plug.

For reference, I bought a “lot” of these NUC’s used and have been deploying them to do specific things around the house. All workloads are small (DNS server on this one so far, will also be adding the HABridge software to it soon) and I did set the firmware on all of the devices up exactly the same before deploying them… Factory reset, firmware update to latest version, then a few basic settings like turning off secure boot and having the device power on with power restoration. I created a base install of OPENSUSE on a brand new SSD and then imaged the drive to other new, identical SSD’s to deploy the systems themselves. I can’t really make these any more identical to each other than they are, and that includes not having things like sleep mode enabled on them.

Once the system is booted up and running, the max draw is about 7-8W with it commonly being 5-6W. That’s a huge part of why I went this route for replacing my Xeon-based workstation class machines… Electricity costs are out of control here and cutting my power consumption for the home lab by over 80% was a major positive.

#4

I thought I would share an update based on my interactions with the manufacturer around this.

First, I want to call out Minoston at this point for being a company that 100% stands behind their products are are willing to provide excellent customer support.

With that said, the products themselves aren’t really living up to expectations as of yet.

I purchased about a dozen plugs made by Minoston - 6 of them are MP21Z and 6 of them are MP21ZP. The MP21Z plugs have no power monitoring hardware or firmware in them - they are “just” a controllable plug. I have them all in use supporting a few different kinds of workloads (table lamps, desktop PC’s, Intel NUC low-power PC’s, etc.) and have experienced zero issues with them.

The MP21ZP plugs are identical to the MP21Z except they contain additional hardware and firmware logic to detect and measure electrical flow through the plugs to show usage. The six plugs I originally purchased are date stamped 0222 and show “V2.0” on the plug base. I have done a fair amount of testing (“using”) of them so far with two repeatedly having a failure, one having one failure so far, two being able to operate as expected (24x7) for as long as two weeks so far, and the last one having no issues but also only operating about 4-5 hours per day on a schedule (desktop PC).

When any of these plugs has had a failure, it must be unplugged from power, allowed to sit for a few seconds (to “reset”?), and can then be plugged back in and used again. Minoston seemed to imply that that the failure may be due to the hardware/firmware detecting an overheating condition and disabling the plug until a hard reset is done (remove from power as described).

One of the repeatedly failing plugs was replaced by Minoston with a newer version that is date-stamped 0722 and has a slightly updated / lower profile design for the power button on the side (slimmer). This plug was tested and failed after about 1.5 days of continuous use for a NUC (low power draw) and it is now completely dead - no matter how long I leave it unpowered, it does not work once plugged back in.

Minoston is sending me more replacements to continue to test, and has offered to supply firmware updates (which I will hopefully be able to do as I move OFF of Vera and onto much newer hardware).

Given that the ZP plugs seem to be the ones with issues, my guess is that there’s some sort of issue with the hardware and/or firmware they are using to detect and monitor current flow. Also, since the newer design seems “worse” (one failure and it’s dead), I’m wondering if there has been a change to the hardware being used internally for this as well.

For now, I am discontinuing purchasing or even putting into use any new (or currently not used) Minoston plugs and will be actively moving to swap in Aeotec Smart Switch plugs where I need stability for extended use. I do hope that Minoston is able to determine the root cause of the issue and correct it because the overall size, design, and price point of these plugs is attractive.

#5

Hi @ ember1205] . I have the same problem. Sometimes MP21ZP plug do a kind of “flicking”, making on and off several times. I connected this plug to a freezer in my kitchen and several times I hear a “flicking” noise from the minostat MP21ZP. Has there been any progress on your issue?

#6

No. I have written them off as being of any use for anything besides lamps. I can’t count on them for anything more significant.

#7

I wonder if the load type is the problem here. A freezer is essentially a motor that is highly inductive. Computer power supplies are typically capacitive on the front end although they usually have power factor (PF) correction designed in. PF correction is for continuous operation though and not for inrush current when plugged in (or switched on by a relay).

So I think the problem is you have a contact rated for 15A RESISTIVE load. You have either high inrush (capacitive) current or high voltage → L di/dt when dumping an inductive load. Both are not the best for relay contacts.

An alternative might be to put a definitive purpose contactor with a 120VAC coil after the minostron. Then the ministron has only to power a small inductive coil. Then you can select contacts which are more substantial for the ultimate load. There will be some wasted power with the additional coil to power when “on” but this might be the price to pay for a more robust operation.

#8

I’m not sure… I have an Intel NUC5 that I did a fair amount of testing with using four or five different plugs. Two of the plugs worked fine for extended periods of time while the others all did some sort of reset while in use. None of them failed at power on, ever. And the NUC is a very low overall draw (about 20-25W, fairly constant). In fact, I had it only booting up to the point where it would throw an error of no boot device found and then just sit there.

I’ve relegated them to use for lamps only at this point as it’s the only thing that seems to not crash itself with.