VC-115 Voltage Relay from Novatek-Electro

I'll start with a quick announcement: to keep up with new posts on the blog, I recommend following me on Instagram, where I'll post notifications about every new article and maybe write about something interesting now and then — link to my account

Today I'm reviewing a voltage relay from the fairly well-known Volt Control series, specifically the VC-115 model.
Inspection, teardown, tests, conclusions—as usual.


So, the relay in this review is the VC-115. Novatek makes a lot of different relays, which is a good thing in its own way. But honestly, I think the huge range works against the manufacturer in this case: buyers can easily get confused about which one they need. The large selection also complicates logistics, which can have a negative effect on the price.
The link in the heading goes to the Ukrainian Rozetka store. There's also a separate link to the manufacturer's website. I couldn't find the VC-115 on the Russian site; they only have the VC-116.

I'll try to clear things up a little. Besides the 16 A VC-115, they also make at least these models:
RN-116, which, as far as I can tell, is the same as the VC-115, but for some reason costs a little less — link
RN-117, essentially the same as the previous models, but without the voltage display or threshold adjustment. It's the cheapest option — link
RN-122, again, basically the same as the 115 and 116, but with buttons instead of knobs. More reliable, but less intuitive — link
RN-101M1, from a slightly different series, but I decided to include it too. It adds current and power readouts, as well as adjustable protection against excessive load current. This relay costs more than the previous models and is functionally closer to the RN-263t, but has a lower current rating and a different form factor — link



Even from the packaging, it's clear that this device is aimed more at the consumer market: a bright little box, lots of information, and a photo of the device.


Inside, the voltage relay sits in a cardboard tray, along with the manual.


The manual is different too: larger font, a color illustration, glossy paper—and, as it turns out, a simplified description. The manual, like the packaging, states that the warranty period is 10 years. By the way, I'm curious: how many people have contacted Novatek about warranty claims, and how did it go?


Technical specifications from the manual.


It looks pretty good. There's really nothing to nitpick. The EM-126T has the same enclosure, though there the T suffix indicates a temperature sensor, while here it denotes the black version.


As you can see, this device uses a plug-in socket form factor, so it plugs directly into a wall outlet. The socket is rated for a maximum current of 16 A, and the relay itself is also rated for a maximum of 16 A. There's a grounding contact.
The front panel has a three-digit, seven-segment display that normally shows the input voltage, as well as the settings while you're adjusting them. To the right is an LED indicating that voltage is being supplied to the output. Below are three knobs: turn-on delay (5–900 s), lower threshold (160–210 V), and upper threshold (230–280 V). The voltage adjustment scale is marked in 5 V increments, but the display also shows the selected setting as you adjust it.
The socket has safety shutters. A standard Europlug fits perfectly, but an older-style domestic “Euro” plug didn't always fit.


Dimensions and descriptions of the controls and indicators from the manual.


Disassembly is straightforward: remove three screws and you can access the internals.


The control board and the socket—that's basically it. One thing to note: unlike the EM-126, the wires here are different colors, although there's still a yellow-green wire, and it's not being used as a ground wire.


On top of the board there's just the display, three trimmer potentiometers, and an LED. Another characteristic feature of Novatek devices is also evident here: the power traces are reinforced with solder. I would have reinforced them with soldered wire, but that's a minor detail.


All the other components are on the back, including an Omron relay rated for a maximum current of 16 A and the power supply's ballast capacitor.
Yes, just like before, this uses a ballast-capacitor circuit and a bunch of zener diodes rather than a voltage converter. Still, if the manufacturer offers a 10-year warranty, they must know something.


The device is built around an Atmega48 microcontroller. The assembly is neat, though I did notice a couple of minor issues: the ballast capacitor isn't secured, and the SMD components aren't glued down. Maybe I'm just nitpicking.


It's hard to say much for certain about the quality of the contact group, since that can only be judged over time. But it holds the plug firmly, and I didn't notice any heating during testing with a 10 A load.


I put it back together and tried turning it on. Everything seems fine; it even showed the same voltage as my wattmeter.
Power consumption with no load but the relay switched on is about 1 W, although with this circuit the power consumption doesn't depend on whether the relay is on or off.


As usual, I tested it across the entire specified supply voltage range, and beyond.
1. The relay tries to start even at 20 V. You can't see it in the photo, but the indicator flickers faintly.
2. At 30 V, the indicator still flickers, but its brightness is already almost the same as in normal operation.
3. At 50–55 V, it starts up and the relay enters normal operation, immediately displaying the correct voltage.
4, 5. At 75 and 100 V, the voltage is displayed, but for some reason it's noticeably lower than the actual value.
6, 7, 8. Measurement accuracy improves in the 150–250 V range, which is the relay's main operating range.
9, 10. As the voltage increases further, the difference grows again.
11, 12. At 385–390 V, the displayed voltage matches the actual value, but as the voltage rises further, the difference starts to show up again, this time in the opposite direction.

The relay measures voltage the same way as the other models. Apparently, it's calibrated around 200–220 V: readings below that are low, readings above it are high, and above 390 V the readings are low again.
I suspect it uses the same firmware as the other models, at least the part responsible for voltage measurement.


The manual doesn't explicitly state the voltage measurement error; it only says that the
accuracy of the voltage trip threshold is no worse than 3 V.

That's pretty much what I found in practice: measurement accuracy is best in the 150–260 V range, which is also where the thresholds can be set.
1. With the cutoff threshold set to 160 V and the voltage raised gradually, the relay switched the load on at an actual 165 V, with 163–164 V displayed.
2, 3. The upper threshold was set to 255 V. The relay switched off at an actual 254 V, with 255–256 V displayed. As the voltage was then lowered, the relay switched on at an actual 250–251 V, with 251–252 V displayed.

On this parameter, as with voltage measurement accuracy, everything meets the specifications, including a hysteresis of at least 4 V.


The device also handled an elevated input voltage for half an hour without any trouble. It started at 450 V and gradually rose to almost 460 V. The manual specifies a maximum voltage of 400 V, which makes sense: getting any higher in a typical home is practically impossible.


1. In normal operation, the case temperature was around 35–40 degrees.
2, 3. With the voltage raised and the device positioned horizontally, the temperature rose to 50 degrees. You can see that the hot spot shifted toward the zener diodes, since the relay is off in this mode.

Interestingly, the LED shows up as the hottest spot in all the thermal images.


As an extra, I decided to check the voltage drop at different points in the power circuit and estimate the losses. I tested at about 10 A and also calculated the losses at 16 A.
1. Contact group: 21.3 mV, power loss 0.213 W; at 16 A, 0.55 W.
2. Connections to the circuit board, i.e. the contact group plus the board trace: 24.2 mV, power loss 0.242 W; at 16 A, 0.62 W.
3. Voltage drop between the relay plug’s internal terminal and the load plug pin: 65 mV, for a power loss of 0.65 W. At 16 A, 1.66 W would be expected.

Based on my measurements, I’d say it’s best to limit the current to around 10–13 A for more reliable operation. 16 A is also acceptable, but not for continuous use.


Since I had it apart again, I also measured the temperature with the case removed at normal mains voltage. The hottest component is the voltage regulator IC, but in my opinion, none of the components get particularly hot.



While adjusting a setting, the display shows the value being set.
1. In recovery-time setting mode, adjustments are in 1-second increments up to 10 seconds, 5-second increments from 10 to 60 seconds, 30-second increments from 60 to 300 seconds, and 60-second increments beyond that.
2, 3. When setting the trip thresholds, the minimum adjustment step is always 1 V.


Now for the most important part: disconnecting the load when it goes outside the set limits—or, more precisely, how quickly that happens.
The device supports five response modes for fault conditions: two for undervoltage and three for overvoltage:
1. Voltage drops below the set lower threshold — 7-second delay.
2. Voltage drops more than 60 V below the set threshold or below 145 V — 0.12-second delay.
3. Voltage rises above the set threshold — 1-second delay.
4. Voltage rises more than 30 V above the set threshold or above 285 V — 0.12-second delay.
5. A voltage spike above 420 V (peak) — 0.02-second delay.

A brief note on the last item: it seems to refer to peak voltage, while the first four refer to RMS voltage. So if the RMS voltage rises above about 300 V, the relay should trip in 0.02 seconds, or one cycle.

First, let’s test the response to undervoltage.
1. A small drop below the set threshold: the specified delay is 7 seconds.
2. A drop of more than 60 V below the set threshold or below 145 V (below 130 V in this test). As far as I can tell, the relay handles both cases the same way.
By the way, the 60 V drop condition seemed a little odd to me. For this protection to trip before the 145 V minimum threshold, you’d have to set the minimum voltage to 205 V. The highest possible minimum threshold is 210 V, so in practice, you can consider the fast trip to occur when the voltage drops below 145 V.
In the second mode, the actual trip time was slightly longer than the specified 0.12 seconds, but the difference is so small that it can be ignored.


Response to overvoltage.
1, 2. A small rise above the set threshold: it tripped in about 1–1.1 seconds, which is fine.
3, 4. Voltage rises more than 30 V above the setpoint, but not enough to trigger the fast fault response: trip time was 0.08–0.1 seconds, versus the specified 0.12 seconds. That’s fine.
5, 6. Voltage rises above 300 V: the relay managed to disconnect the output within 0.5–1 cycle, and sometimes in just 0.25 of a cycle if you measure from the peak to when the output voltage disappears. Excellent.

In all modes, the relay trips at any point in the sine wave and on either half-cycle, so there’s no synchronization.


Reconnection once the voltage returns to normal after an undervoltage (top) or overvoltage (bottom). This process isn’t synchronized to the mains either, so the relay can switch on at any point in either half-cycle.


Conclusion.
In this case, the verdict is mostly positive. That applies to the device’s design, enclosure and assembly, as well as its performance and features.
Yes, the device is clearly designed with non-technical users in mind. As I said earlier, it’s a “consumer-grade” product, but that doesn’t mean it’s worse than “professional” devices; it just requires a somewhat lower level of technical knowledge.
The adjustments are simple and intuitive, as is the display. To connect it, you just plug it in between your wall outlet and the device—no extra tools needed. The manual is much the same: it contains only the essential information, which I think is the right approach.
The device’s operating algorithm is practically the same as that of other protection devices made by Novatek, so it’s well proven and I have no complaints about it.

There are a few minor quibbles, of course; it’s hard to find a device without any. But they’re things like the color of the internal wires, the lack of a retainer for the ballast capacitor, and so on. And yes, many thanks for using a not-too-bright green LED instead of a poisonous blue one. It’s also positioned so it’s barely visible from the side.

I do have one suggestion, though. The device has a fixed hysteresis of about 4–5 V. Speaking as someone who’s already had a neutral wire burn out at home, I can say that’s sometimes not enough. When the neutral burns out, the voltage doesn’t just jump—it starts fluctuating wildly, and can easily hover around the point where the relay keeps trying to switch the output back on. That’s exactly what happened to me at home with the EM-129. It helped that at one point I was able to connect to it, lower the minimum threshold, and increase the hysteresis.

In short, it’s a decent device, although I’d limit the continuous load current to 10–13 A.

That’s all from me. I hope this information was useful and helps make using your electrical devices safer.