Voltage relay UZM: purpose, types, connection diagrams

Electrical safety is one of those issues that requires maximum attention. It seems that people have already become accustomed to the need to protect people and networks. But we are gradually coming to the need to protect electrical appliances. The more expensive the equipment we buy, the more we think: even repairs will cost a lot, and there is virtually no one to file a claim with. There is an inexpensive - for a couple of thousand rubles - device that can protect equipment from too low or too high voltage. This relay is protected against overvoltage. Previously, we looked at the Easy9 voltage relay with fixed settings from the French company Schneider Electric. The article will focus on one of the brands - UZM, produced by electric (Russia). Relays of this brand protect against short-term pulse emissions, and some types also protect against sparking.

What is UZM and why is it needed?

UZM is an abbreviation for the name “Multifunctional Protection Device”. This small device (35 mm wide) is mounted on a DIN rail. Any UZM can be installed in any type of network - TT, TN-C, TN-S, TN-CS. Performs several tasks (it is also multifunctional):

• Turns off the power supply when the voltage is too low or too high. Both options - too low and too high voltage - can cause damage to household appliances. When the network parameters are restored, power is automatically restored.
• Smoothes out pulsed (short-term) voltage surges that occur when turning on/off certain types of equipment (the same motor in a refrigerator or freezer).
• Models UZM-50MD and UZM-51MD monitor the appearance of sparks in the wiring and turn off the power in this case.

UZM consists of three parts

That is, the installation of UZM extends the life of trouble-free operation of electrical wiring and devices connected to it. Also, some modifications - with the prefix “D” - protect the house/property from fire. Knowing the state of networks in our country, we can definitely say that surge protection relays are worth using. Both in the house and in the apartment. This device is not needed if a stabilizer is installed at the input, smoothing out all the unpleasant moments. But the price of these devices does not allow everyone to use them, and UZMs cost about 2-3 thousand rubles. The replacement is not entirely equivalent, but effective. You can use not only UZM - devices with similar functions are also available from other manufacturers. They may be called differently, but they perform the same tasks (or almost). So there is a choice.

Functions of UZM and alternative devices

Devices with the name “UZM” of various modifications are produced by Pitersky. The design is constantly being worked on, new models with new characteristics or capabilities appear. But not only this is captivating, but the fact that the service is surprisingly well organized. During the warranty period, faulty devices are repaired or replaced without question. The warranty is given for 5 years. Calculated from the date of sale. If the date of sale cannot be tracked (lost your passport), count from the date of production (marked on the case). If you travel far, you can call and everything will be explained to you over the phone. Overall, not a bad service.

Installation and connection diagrams

The UZM-3-63 device has a mount for mounting on a 35 mm wide DIN rail. It can be installed openly in the electrical distribution panel or in a plastic case. Vertical and horizontal arrangement of the housing is allowed.

There are two connection schemes:

1. When conductor N is connected to both input and output terminals of the device
2. When the N wire connection is made only at the input terminal

Diagram in which conductor N is connected to the input and output of the device

Diagram in which conductor N is connected only at the input of UZM-3-63

For normal operation of the device, the zero terminal must be activated..

Device and appearance

UZM-50M and 51M, 16M consists of two parts. There is a varistor at the input - it smoothes out short-term surges or sags in voltage that occur when equipment with electric motors is turned on. At the output there is an electromagnetic relay that turns off the load when there is dangerous voltage in the network. Models 51 MD and 50 MD add another device - spark detection. So the modification with the letters “MD” is fireproof.

The terminals can connect conductors with a cross-section of no more than 35 mm² (in the UZM 16 model, wires up to 2.5 mm²). Line wires are connected to the upper terminals, the load - to the lower ones. When triggered, only the phase wires are broken, the neutral is not switched. She goes straight to the exit. Any of the devices can be installed either at the entrance to a house or apartment, or at individual groups of consumers.

External differences are clearly visible. UZM-50MC has a digital indicator, thanks to which you can quickly monitor voltage, current and power

The front panel of various modifications may have significant differences. However, any model has operation/emergency shutdown indicators (green - in operation, red - disabled). There is an LED that changes color depending on whether a shutdown occurred due to an “arc” or due to emergency voltage parameters. There are also manual control buttons, in the UZM-51MD modification there are knobs for adjusting the limits for turning on and off the power supply.

Design features

Externally, the product is a single housing with four input (N, L1, L2, L3) and output terminals (N, U, V, W). On the front panel there are regulators for setting the triggering voltage (U max, U min) and the switching time after triggering. They have a setting scale on which the user can select the values ​​of interest. LED indicators are also located here: green - indicate the presence of phases L1, L2, L3; red – about overvoltage (U>) or undervoltage (U<); yellow ( ) – about the operation of the power relay.

The following elements are located inside the case:

1. The basis of the protective device is a powerful three-phase polarized relay, which allows the circuit to be closed/opened at high current values
2. Varistors installed on each phase provide protection against pulsed network surges due to the ability to change their resistance depending on the magnitude of the incoming voltage
3. Contact block driven by a power relay.

A schematic representation of these parts is shown in the figure below.

Built-in design elements of the UZM-3-63 protection device

Models and their characteristics

Meander's assortment today includes six UZM models for single-phase networks and one for three-phase networks. The parameters are basically the same, the functionality differs. Models are available in two climatic options (except for 50Ts, which is only available in the UHL4 version). What is the difference between UHL 2 and UHL 4? UHL2 tolerates lower temperatures:

• UHL 4 can operate at temperatures from -25°C to +55°C,
• UHL 2 operates from -40°C to +55°C.

Once again: the difference between UHL 4 and UHL 2 is only in the lower temperature limit. UHL 2 is more “frost-resistant”. They should be used in the northern regions of the country when installed outdoors. When installed in a heated room, the climatic design does not play a role.

A few words about UZM 16. It is also designed to turn off the power in the event of a decrease or increase in voltage and smooth out pulse surges. But you can connect wires with a cross-section of up to 2.5 mm² to it. The rated load current is 16 A. This means that the device can be installed on separate groups of consumers. It can also be used in the country if the total load does not exceed 4 kW.

Analogue devices from other manufacturers

Considering products from different brands designed to perform functions to protect electrical equipment from possible changes in the state of electrical networks, one can note the high quality of workmanship and versatility of these devices. They differ in name and may have differences in design, but they share a common purpose. For comparison, users are invited to familiarize themselves with some of them:

As you can see from the table, the difference in prices between products from different manufacturers is insignificant. But unlike Meander products, products from other brands require the use of additional starting devices in the circuit, because the designs of these devices provide insufficiently high switching capacity:

• the changeover relay switch in the product from Ukraine RNPP-302 is designed for a current load of 8A;
• the maximum current of the contactor coil in SR-731 from the Belarusian Manufacturing Company is 2 A;
• max load capacity of the contact of the Polish analogue PNM-31 – does not exceed 16 A.

Such values ​​cannot provide independent switching of powerful consumers, and can only serve to control the load starter.

Analogues of protective devices for monitoring the state of a three-phase network

Another advantage of the UZM-3-63 is the possibility of remote control through terminals Y1 and Y2, located in the lower left corner of the front panel of the device.

However, some analogues also have positive design features that distinguish them favorably. For example, RNPP-302 has a digital display that visually demonstrates the state of the electrical network, which provides certain convenience during operation.

Main characteristics of UZM

Parameters of a universal network protection device against overvoltage and surge currents
Models UZM 50 M and 51 M differ in that conductors of larger diameters (up to 35 mm²) can be connected to them. Accordingly, they have a higher rated load current - up to 63 A. Modifications with the letter “D” - 50 MD and 51 MD - differ in that they have built-in spark protection. And the UZM 51 series is distinguished by the fact that it has manual adjustment of the voltage shutdown parameters. Using the manual regulator located on the front panel, the shutdown limits for high or low voltage are changed.

UZM-50TS and UZM-50MC (fire) are equipped with a digital indicator, which by default shows voltage and switches to measuring current and power. Of course, you can use the UZM-51MD, and install a separate VAR-M01-08 AC20-450V UHL4 voltammeter on a DIN rail in the electrical cabinet. But, if you need to save space, it is better to use UZM-50MC. There are other differences - you can select the response delay in a wide range from 10 sec to 360 sec, built-in non-volatile memory, where the number of shutdowns, minimum and maximum voltage values ​​are stored . And, as in other 50 series models, adjustable shutdown thresholds for overvoltage and undervoltage.

Principle of operation

Using the regulators installed on the device body, you can set the relay operation limit for the upper voltage from 240 V to 290 V and for the lower voltage from 210 V to 100 V.

When connected to the power supply, the indication on the UZM-51M does not work within the first 5 s. A flashing green light indicates that voltage testing is in progress. If it corresponds to the specified parameters, the electromagnetic relay turns on, and this is indicated by the uniform illumination of the yellow and green LEDs.

Reference. You can speed up the startup of the protective device by pressing the “Test” button.

In normal operation, the UZM-51M controller constantly monitors the voltage level, and the varistor dampens its pulses to an acceptable value.

The operation of the light indication differs in different emergency modes.

A flashing red indicator warns that the voltage is significantly higher than normal.

If the yellow LED goes out and the red LED lights up continuously, it means that the voltage has exceeded the set value and the relay has disconnected the load.

A flashing green indicator indicates that the restart time countdown has begun.

The green and yellow LEDs, which are constantly on, indicate that the voltage has completely returned to normal and the relay is turned on.

Attention . The restart time can only be set to 10 seconds and 6 minutes.

If the green LED on the panel begins to blink while the yellow LED is constantly on, it means that the incoming voltage has decreased significantly.

The flashing lower indicator, which has changed from green to red, signals that the countdown of the electromagnetic relay switch-off time has begun.

The red LED flashes every two seconds and the yellow one goes out to indicate that the relay is turned off.

When the voltage normalizes, the alarm works as in the first case.

Alternately flashing red and green lights remind you to start the device by pressing the test button again.

UZM-3-63 |

Otherwise, I would like to note that UZM-3-63 is equipped with remote control terminals, monitors phase breaks and rotation, and controls the network frequency. In addition, the device can switch high current, 63 amperes in one phase.

Expert opinion

It-Technology, Electrical power and electronics specialist

Ask questions to the “Specialist for modernization of energy generation systems”

UZM-3-63K: overview, characteristics, connection Brand of voltage relay UZM-51M PH-111 DigiTop Zubr Rated current, A 63 16 63 63 Upper voltage limit, V 290 280 270 280 Lower voltage limit, V 100 160 120 120 Operation time , s 0.02 0.1 0.02 0.05 Space in the panel, number of modules 2 2 3 3 Restart time, s 10 or 360 From 5 to 900 From 5 to 900 From 3 to 600 Voltage level indication on screen no no yes yes. Ask, I'm in touch!

Where to install UZM

As we said earlier, a voltage relay can be installed at the entrance to an apartment or house, or at all or some groups of consumers. Sometimes it can be difficult to choose a place to install the UZM. What can be said for sure is that it is placed after the introductory machine and, most often, after the electric meter. In principle, it can be installed before the meter, but only if the operating organization agrees. And they rarely give consent to this. Therefore, usually, the UZM is placed after the meter.

Two scheme options with UZM

The power supply circuit may also contain a fire protection RCD. So where should you put the surge protection device? Before the fire protection RCD or after? If you put it in front, then when the power is turned off it will be out of action. And if after, it may be damaged as a result of jumps. In general, decisions here are made individually. We can definitely say that the voltage relay must be installed before the first branch to consumers.

Connection in three-phase networks

There are special models of protective modules for three-phase networks - UZM-3-63. All three phases are connected to this device at once, and further supplied from the output. When triggered, all phases are switched off simultaneously, so that the power is lost completely. This is not always convenient, since problems usually arise with one of the phases.

Connecting a three-phase UZM

The issue can be resolved by installing one UZM for each phase. Then, if there is a imbalance at some phase, the rest will be in operation. It's more convenient. But this connection method - three single-phase UZMs - is not suitable if there is a three-phase load. In this case, when installing three separate UZMs, when disconnected in one of the phases, there may be a “flow” through the load to the adjacent one. So the choice is yours.

Purpose and scope of application of the product

UZM-3-63 provides frequency control of a three-phase power supply network, protects equipment from an increase or decrease in incoming voltage, pulsed network interference, violation of the phase sequence or the disappearance (break) of one of them. Each of the listed violations can lead to failure of electrical appliances or significantly affect the quality of their operation. The protection device can neutralize the negative effect or perform a protective shutdown.

For example, pulsed voltage surges that occur when turning on/off powerful consumers (electric motors, welding machines, etc.) have a detrimental effect on the electronics of other equipment connected to the same network. Similar interference can occur during surges at transformer substations. All phases of UZM-3-63 have semiconductor varistor protection, which can preserve the consumer and its operability during pulse overvoltages with a current amplitude of up to 6.5 kA.

The maximum current value in each phase, at which the relay’s ability to switch contacts is maintained, is 63A, which is a high indicator and allows the device to be used without using a magnetic starter in the circuit. UZM-3-63 can be used both at production facilities and in administrative buildings or households to connect three-phase current consumers.

The device does not protect against the destructive effects of short circuits, and also does not respond to current leaks, therefore the use of protective equipment such as AV and RCD in the electrical circuit is mandatory.

What is the difference between UZM and RCD?

It must be said that the overvoltage protection relay in any version does not replace the RCD or circuit breaker. These devices complement each other, making protection more reliable:

• The machine ensures that the wiring does not overheat.
• The RCD turns off the power when leaks occur - insulation breakdown or when a person touches live parts.
• The UZM monitors the mains voltage, turning off the power if the parameters go beyond the established limits.

Functions of various household electrical protection devices

As you can see, all three devices are needed. As a rule, when assembling a panel for a house or apartment, they neglect to install the voltage relay. This is extremely short-sighted, because UZM extends the life of electrical appliances and electrical equipment in conditions of unstable network voltage. In the version with spark detection - 51MD and 50MD - it also increases fire safety. Which is very important in wooden and frame houses, but not only for them. According to statistics, about 15% of fires occur due to a spark in the wiring. So monitoring sparking is really important.

What problems exist in a home network and how to protect subscriber networks from parameter discrepancies

• exceeding the permissible voltage by more than 10%;
• reduction in network voltage (sag) by more than 10%;
• short-term sudden increase or decrease in voltage;
• alternating current frequency change;
• sparking, arcing on contacts when a powerful consumer is turned on;
• zero break, as a result - phase imbalance;
• short circuit on the line or inside the electrical appliance.

Some of these problems arise due to the fault of the user (maintaining equipment and lines in poor condition), some due to the fault of the energy supply company. Let's talk about this in more detail.

The quality of energy supply depends on a number of reasons:

• deterioration and compliance with the design load of power lines;
• technical condition (and actual availability) of transformer substations on each subscriber line;
• the functionality of the automation to maintain normal electrical network parameters;
• load distribution between phases;
• legality of connecting new subscribers (there are cases of exceeding technical specifications).

Let's give an example

Condition: three-phase input into a multi-storey building, common zero, phases “A”, “B” and “C” are evenly distributed between entrances 1, 2 and 3. For any reason (corrosion, mechanical damage, etc.) the zero breaks. At this time, entrance 1 is at maximum load (boilers, electric ovens), entrance 2 is at medium load (refrigerators, lighting), entrance 3 is at minimum load (a couple of TVs and several computers).

What will happen with each phase?

1. Phase "A" - 1 entrance. The voltage will drop to a minimum value, close to zero.
2. Phase “B” – 2nd entrance. With a high degree of probability, the voltage will remain within 220 V, although a floating change in potential is possible.
3. Phase “C” – 3rd entrance. On a line with minimal load, the voltage approaches the value between phases, that is, about 380 V.

Since the operating current for each connected subscriber (group of subscribers) did not exceed the set value, the current protection circuit breaker will not work. Electrical appliances on line “C” (3rd entrance) will fail, or in the worst case, they will simply burn out. Often this situation leads to a fire.

As a rule, we don’t think about the fact that the electricity connection to our meter is not single-phase at all. This applies not only to holiday villages and small villages. Any subscriber network in cities, be it Moscow or a regional center in the Far East, is created according to a single principle.

You can install an individual transformer substation or a powerful stabilizer. But the cost of such equipment may exceed losses in an emergency on a 220 V line. What is the solution? Install the UZM protection device.

Information: Among home electricians, multifunctional ultrasonic automatic devices are popular, which also protect against power surges, arcs or sparks.

In terms of operation reliability and degree of protection, the devices are similar. However, the protection device is multifunctional: for example, UZM 51M, closes the circuit independently after restoring the power supply parameters. But the AFIS must be turned on manually.