Three-phase voltage relay: connection diagram and features, price

A modern electrician in a house or apartment represents a wide variety of technical means that require control over the supply of voltage. Power management produces a voltage relay three-phase, closing or breaking electrical circuits in the event of an emergency.

Purpose of the voltage relay

Most protective devices contain control electronic relays. If the monitored parameters are deflected beyond the preset limits, they are triggered by disconnecting the circuits. All relays consist of three elements. The first of them is perceiving. It transmits the value of the controlled quantity to the intermediate element, where it is reconciled with the normative indicators. With deviations, the signal is transmitted to the executive device, which turns off the power.

Voltage surges in the supply of electricity, as well as interruptions in the power circuit can cause the failure of consumer equipment. In worn-out electrical networks, there may be phase coalescence or the zero-wire burnout, which leads to voltage distortions from 0 to 380 V. All connected household electrical appliances that do not have protection can be damaged.

The three-phase voltage relay serves to instantly react to an increase in voltage above the permissible voltage and to open the electrical circuit. The phase turns off when there is a magnetic flux in the electromagnet as it passes through the current winding. With the help of the electronic circuit, the relay is adjusted to certain voltage limits, when exceeding the electrical contacts in the load circuit.

The voltage relay is installed in the apartment electrical panel, but there are models that plug into the outlet. With their help, the lower and upper limits of the voltage change are selected. It is convenient to set the range of 180-245 V, and then additionally configure so that the number of trips is no more than one per month. When the voltage in the network is constantly high or low, it is advisable to install a stabilizer.

The connection of the three-phase voltage relay must be done after the input automaton, the nominal value of which is selected one step smaller, for example, in the ratio 32 A and 40 A.

The three-phase voltage relay is connected to the live and neutral wires of the network, as well as to the load connection output terminals for monitoring their condition. Changing the modes is done by switching jumpers on the relay terminals. When activated, its coil de-energizes and opens the power contacts. With them, the winding of the power contactor can be connected, which also works, disconnecting the consumers. After a time delay, when the voltage is restored again, the relay returns to its original state, closing its power contacts.

The above diagram disconnects consumers when a problem arises on the network. The protection can also be built on 3 single-phase independent voltage relays. It is used for individual loads on each conductive conductor wire. Power contactors are not normally used here, if the load is not more than 7 kW. The advantage of the method is to keep the voltage on the remaining phases when one of them is switched off.

Features of common types of voltage relay

Apparatuses differ between each other with functions and quality. Depending on whom, for what purposes you need such devices, they are selected and installed. Next, consider the most popular devices.

Relay RNPP-311

The device protects the network during the following accidents:

• Exceeding the voltage of the set values;
• Closure or interruption of phase sequence;
• Skew or phase breaks.

The device also monitors other network parameters and disconnects the load power when they deviate from the norm. Three-phase voltage relay RNPP-311 can be tuned to two monitoring modes.

• Linear - operation on the phase skew, when for the consumer there is no danger of a zero offset.
• Phase - when phase distortion of phase voltages and displacement of zero are inadmissible.
  

On the front panel are indicators of the presence of voltage, load connections and some abnormalities. The adjustment is made by six potentiometers. The following parameters are set:

• Boundary values of the maximum and minimum voltages, as well as the limiting value of the phase misalignment;
• Time delay of load disconnection in case of accidents;
• A delay in connection to the network after the parameters are restored.

The device remains operable when zero and one of the phases remain active or at least two.

Relay RKN-3-15-08

The device serves for the following monitoring methods:

• Voltage in phases;
• "Sticking" of conductors;
• Violation of the order of phase rotation;
• Deviation of voltage beyond the specified range.

The thresholds are set by two potentiometers. The display allows monitoring of voltage, network faults and activation of the built-in electromagnetic relay. Operating conditions are normal.

The scheme of connection of the three-phase voltage relay RKN-3-15-08 practically does not differ from the one given earlier. It only has a simpler setup. On this voltage relay three-phase price is slightly lower than at RNPP-311. It is about 1500 rubles. Different modifications of both types can significantly differ in cost, it all depends on the functionality.

Apparatus for the ASP series

In a separate series there are completely digital protection relays of the ASP series. Most of them no longer find tuning elements for analog signals. Potentiometers depend on the influence of the external environment, quickly age, the values change, and contact often disappears.

Digital devices do not contain contact mechanical parts, due to which the effect of external factors decreases, and their reliability increases. In appearance, the devices are characterized by a digital display. The price they have on average higher, but you can find a budget position.

The ASP-3RMT relay

The model is basic, and it has all the most necessary functions that a three-phase voltage relay must have. Its price is 2 times lower than other devices with built-in digital voltmeters and screens. If no display is required, and protection is needed, the device is perfectly suitable for installation.

The relay ASP-3RVN

A three-phase voltage and phase control relay with a microprocessor is used to control the supply of electricity to refrigerators, air conditioners, compressors and other devices where electric motors are used. The device is convenient in that it allows you to monitor the voltage on each phase of the display, as well as monitor its asymmetry. Built-in memory with power from an independent source makes it possible to memorize the parameters and the number of emergency trips with the ability to display. This does not require special skills for customization. Additional functions are available via the control buttons.

The ASP-3RVN device is connected to the network in parallel to the load in the same way as the ones presented earlier. The device monitors the operating voltage of the network. In the event of an accident, it opens its contacts, which are included in the breakage of the starter winding. After the power is connected and applied, the protection relay checks the presence of voltage. This is signaled by three LEDs. If the sequence is interrupted or the phases stick together, dashes (-) are displayed on the indicator. Further, the measured phase voltages are displayed on the screen with an interval of several seconds. The corresponding LEDs light up.

In case of an accident, the reasons for its occurrence are displayed on the screen. The settings are first factory settings, but they can be changed by pressing the corresponding buttons. If errors occur during the installation, they can be reset and reset to factory defaults with a single click. All settings are stored in memory and can be checked.

Monitoring relays ABB

One of the known devices for the protection of electrical equipment is a three-phase voltage relay ABB. The device has proven to be one of the most reliable when the balance of voltage is disturbed. For three-phase networks, the ABB SQZ3 device has been designed to withstand a voltage of up to 400 V. A large assortment allows choosing a suitable model for certain operating conditions. The device allows you to monitor:

• Network voltage with load disconnection in emergency situations;
• Misalignment, disappearance and correctness of phase alternation with signals in deviations.
  

ABB has established itself as a reliable supplier of high-quality electrical equipment, easy to operate and versatile.

Conclusion

The three-phase voltage monitoring relay is a necessary part of the power supply system to the devices. It will reliably protect the electricity network of the apartment or house, as well as expensive electronics from jumps and voltage distortions.