Minitest: DigiTOP VP-16Af voltage relay for photovoltaics

Here I will introduce the DigiTOP VP-16Аf voltage relay designed to protect electrical equipment from excessive electrical voltage. It offers a simple LED display and a programmable setting for the upper cut-off limit, hysteresis and turn-on response time. The device is available to buy for around £130.

Let's start with the unboxing and contents of the kit. We also get a small screwdriver in the box, which on the one hand is a nice, but also a strange idea. Rather, the person assembling this type of equipment has a screwdriver.

A Polish-language manual describing how to change the device's settings is also included, so I won't go into that here.

The unit is DIN rail mounted. I haven't looked inside as there is a seal, while I think that a little bit these screw terminals could be more solid.
Time for some videos. Setting the limit voltage:

Hysteresis setting:

Test with autotransformer:

The unit switches on at around 23V, but the result is quite incorrect - it shows 39V. Sensible measurements are from 41V onwards. At voltages above 200V I have seen up to 2V difference. The unit responds correctly, as evidenced by the LED on the front.

Basically that's it for today. That was a basic first presentation, although I might still try to do a second part and measure with an oscilloscope how fast this relay opens. In the meantime, I leave the verdict to you - do you use this type of relay? Or do you know of better alternatives?