RN-119 voltage relay from Novatek-Electro

I already have a review of a decent voltage relay RN-263t, and now I’ve got a simpler, but possibly no less useful, RN-119 relay.


First, a note about the cover image: it shows two nearly identical relays, the RN-118 and RN-119. The only difference between them is the maximum switching current: 10 and 16 A, respectively. The RN-118 is only 10 UAH (35 cents) cheaper, so I don’t quite see the point of it.

The link goes to the Ukrainian version of the site; readers in Russia can switch to the Russian version.

It comes in a small cardboard box, with a sticker on the side showing the model name and the manufacturer’s address.


The package is simple: the instructions (which also serve as the warranty card) and the relay.


The instructions are detailed, though not without a few quirks. They also state a 10-year warranty.


As always, there’s also documentation available electronically. I’ll show some excerpts from it as I go.

And, as always, I’ll start with the technical specifications.

We can already see that the relay has four voltage trip thresholds: two fixed and two adjustable. The RN-263t had one additional threshold.
The fixed thresholds are below 145 V and above 420 V; the adjustable ranges are 160–220 V and 230–290 V. In the first case, the relay trips as quickly as possible; in the second, there’s a delay: 7 seconds when the voltage drops below the set threshold and 0.5 seconds when it rises above the threshold.
I also have a question about the 420 V threshold, but I’ll come back to that in the testing section.



There’s not much new to say about the appearance. It’s a standard Novatek enclosure, though it looks neat.


One of the relay’s key features is its width: just one module, the same as a standard circuit breaker, which can be very useful in some cases.


For connecting the wires, it uses terminals I’ve already seen on other Novatek devices. No complaints about their quality or reliability, though in my opinion they’re still a little on the weak side for a continuous 16 A load.
There’s a wiring diagram on the side of the enclosure, which is handy. The relay clips onto the DIN rail with two spring-loaded latches.


The second feature is that it uses a conventional, non-polarized relay. It’s also a changeover relay, and its contacts are galvanically isolated from the other circuits. This means it can be used not only in the standard configuration, where its contacts break the power circuit, but also to provide a control signal when the voltage goes outside the set limits.
Both wiring options are shown in the instructions.


The front panel has:
1. A three-digit, seven-segment display.
2. Three indicator LEDs: load on, APV countdown (switch-on delay), and maximum-voltage relay mode.
3. A pair of buttons.


The functions of the controls and indicators, along with the module dimensions.


As always, before testing I’ll take the device apart. It’s pretty straightforward: first remove the top cover, then split the enclosure into two halves. There are no screws, just clips, and they’re not too stubborn.


Here it is fully disassembled.


The inside turned out to be fairly simple, at least at first glance, partly because there’s no current monitoring, high-power relay, or thermal protection. That’s neither good nor bad; this relay simply has fewer features, so its design is correspondingly simpler.


The assembly consists of three circuit boards: a main board with the microcontroller, a power supply/relay board, and a display/control board. The whole assembly feels quite rigid.


The bottom board has almost as many components as the main one. The traces to the relay contacts are heavily reinforced with wire, and there are also protective slots between the terminal block contacts. Overall, it’s built with plenty of margin.


1. The input has a noise-suppression capacitor and a capacitive dropper in the power supply. To the right is a relay, which, judging by the marking NT75, is most likely made by Ningbo Forward Relay, with a 24 V coil and 16 A contacts.
2. The small upper board has a display, buttons, and LEDs. The buttons are offset to the right, probably for a reason: it improves ergonomics and puts them closer to the vertical board, reducing the chance of breaking the board when pressing them.
3. An Atmega48 microcontroller and other small components.
4. The power supply capacitor is rated for 35 V, while the supply voltage is 24 V, so that's fine. The LM317 regulator is to the right.


The manufacturer provided the device schematic, and I’d like to thank them for that.
First, the power supply circuit. It uses the same solution as the RN-263


The main board schematic, showing the microcontroller and voltage regulation circuit


And the display and control board schematic. There’s nothing particularly interesting here, but since it’s available, why not include it?


Let’s put it together, power it up, and test it.

When power is applied (in the default operating mode), the display first shows STA, then counts down the automatic restart delay (the power-on delay), and then displays the current mains voltage. If the voltage is within range, the display stays on continuously; otherwise, it flashes.
With the relay energized, the module draws 1.3 W from the mains.


Before testing, I’ll go through the operating modes. The manual describes everything and even includes a diagram, but it’s a little confusing, so I’ll explain it in my own words as I understand it.


There are three menu levels: top, middle, and bottom.
The first mode is opened by pressing the top button. The display then cycles through notifications showing the maximum recorded voltage, the voltage reading, the minimum voltage, and its reading.
Handy, but there’s a catch: once the readings have been displayed, the counters reset. The next time you press the button, the relay will show readings recorded since the previous press.


The second menu opens by pressing both buttons at the same time. Here you can set:
Minimum voltage: 160–220 V
Maximum voltage: 230–290 V
Automatic restart delay: 5–900 s
Relay operating mode (more on this below)

To change a parameter, select it with the up/down buttons, then press both buttons at once and use the up/down buttons to change the value. Voltage changes in 5 V increments, and time in 1 s increments.


1. To enter the third menu, press both buttons at once again while in tyP mode. This opens the relay operating mode settings. Note that you also switch modes with the up/down buttons, but the options don’t cycle around.
The relay can do more than act as a standard voltage relay, so there are several options:
2. Undervoltage relay: the relay is on when the voltage is above the set minimum threshold.
3. Overvoltage relay: the relay is on when the voltage is above the set maximum threshold.
4. Voltage relay: the standard operating mode; the output is switched off when the voltage is outside the set range.
5. Timer relay: when power is applied, it waits out the automatic restart delay and then switches on the load.
6. In undervoltage relay or timer mode, overvoltage protection is disabled, so the relay will remain on even if the input is 400 V.
The 145 V minimum threshold applies in all modes except overvoltage relay mode; that is, the relay will disconnect the load if the voltage drops below this threshold.

There’s a little confusion above. The relay has an “output active” state indicated by an LED. In some modes, the LED lights when the relay coil is energized (voltage relay, undervoltage relay, and timer), while in overvoltage relay mode it lights when the relay is de-energized.


There’s a YouTube video demonstrating all the modes listed above.


The relay tries to start at around 50–55 V and reaches its operating mode at 65 V, by which point it is already measuring the input voltage fairly accurately.
Between 65 and 400 V, the measurement error is up to 4 V. Above that, it starts to increase noticeably: at an input of 455 V, the relay displays just 419 V. I tested it up to 480 V. Apart from the large voltage measurement error, there are no problems; the RN-263t had the same “quirk.”


If you look closely at the photo above, you can see that the relay reads high between 200 and 350 V, and low at 400 V and above. For the sake of the experiment, I found the “breakpoints.”
Above 240 V, it starts reading high; above 390 V, it reads low. In my opinion, this is a software bug that could be fixed, but you can also just ignore it; it’s not that critical.


Since I’d already started torturing it with voltage, I decided to check how hot it gets too. I applied about 425 V to the input and left it that way for over an hour.


There is some heating, but it’s all within normal limits; the temperature did not exceed 50 degrees. I could have applied even more voltage, but didn’t see the point, since it’s not easy to get more than 420 V in the mains for an extended period.


And, to “avoid making two trips,” I lowered the voltage to its nominal value and ran it for another half hour with the relay switched on. The temperature eventually dropped to 40 degrees on one side of the case and 35 on the other. The first thermal image clearly shows where the relay is; it’s the relay that’s generating the heat.


I didn’t measure the voltage drop across the relay contacts alone; instead, I measured the whole assembly, including the relay contacts, conductors, and terminals. Here are the key specs from the datasheet for the installed relay.



At a current of about 9.2 A, the voltage drop was 39.2 mV, giving a resistance of 4.26 mΩ and power loss of 0.36 W. At the rated 16 A, the voltage drop would therefore be 68 mV, and the losses would rise to 1.1 W. I’d say that’s pretty good.


And of course, I measured the response time when the output voltage goes outside the set limits.
As I mentioned, the relay has four voltage thresholds: two fixed (145 and 420) and two adjustable. Let’s start by checking its response to a drop in voltage.
1–4. Voltage drops below the set threshold but remains above the minimum. According to the datasheet, the relay should trip within 7 seconds. That’s about what I got; the trip isn’t synchronized with the mains phase.
5, 6. Voltage drops below 145 V. The datasheet says it should trip within 0.15 seconds; I got around 0.1–0.15 seconds, which is also fine.


Now for an increase in voltage. I’ll remind you that the datasheet specifies a fixed threshold of 420 V, which seemed a little odd to me, since in this configuration the chances of the relay tripping at that level on a household mains supply are minimal—I’d even say close to zero.
1, 2. The threshold is set to 250 V; I applied 255 V, and the relay tripped in 0.45–0.5 seconds, as specified.
3, 4. Same threshold, with 320 and 330 V applied. As you can see, the relay easily trips within the specified 0.02 seconds, which corresponds to the upper (non-adjustable) threshold.


The relay’s turn-on is also not synchronized with the mains:
1, 2. Turn-on after an undervoltage event
3, 4. Turn-on after an overvoltage event.

I’ll also describe the APV timer algorithm here.
If power is completely disconnected, the timer counts down for the full set time. If the relay disconnects the load, then once the voltage returns to normal, power is restored to the load after at least the set time. For example, if the time is set to 60 seconds and the relay disconnects the output for 40 seconds, then when the voltage returns to normal, the timer counts down the remaining 20 seconds. If the relay disconnects power for 60 seconds or longer, it restores the output immediately once the voltage returns to normal.


Since I’ve been comparing this relay with the RN-263t from time to time, we can now compare them visually as well.


In my opinion, this is a useful relay. It’s predictable that it falls short of the RN-263 in some respects, but it still has its place.
The only thing I wish it had is a more advanced overvoltage detection algorithm like the one in the RN-263. That one had three stages; this one has only two.
The relay can be used as a voltage relay in its own right, to control a separate contactor, or to send a control signal to another device. The developers not only managed to fit everything into a single case, but also added a small display, which is very convenient.
In theory, you could also protect a three-phase load by installing three relays with their contacts connected in series and controlling an external contactor, but it’s probably easier to install a dedicated three-phase relay.

Perhaps someone from the manufacturer can clarify the upper threshold: did I misunderstand it, or is there an error in the manual?

In short, I liked it. It works well, the build is neat, the price is quite reasonable, and it comes with a 10-year warranty.

That’s all for now. I hope you found this useful.