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 three-phase voltage relay, making or breaking electrical circuits in case of emergency.
Assignment of the voltage relay
Most safety devices contain control electronic relays. When the controlled parameters deviate beyond the specified limits, they work, turning off the circuits. All relays consist of three elements. The first one is receptive. It transmits the value of the controlled value to the intermediate element, where it is checked against the standard values. In case of deviations, the signal is transmitted to the actuator, which turns off the power.
Power surges during power supply, as well as breaks in the power circuit can cause failure of consumer devices. In worn-out electrical networks, phase sticking or burnout of the neutral wire can occur, which leads to voltage imbalances from 0 to 380Q. This may damage any connected household electrical appliances that are not protected.
The three-phase voltage relay serves to instantly respond to an increase in voltage above the allowable one and open the electrical circuit. The phase is turned off when a magnetic flux occurs in the electromagnet when current passes through the winding. With the help of an electronic circuit, the relay is adjusted to certain limiting voltage values, when exceeded, the electrical contacts in the load circuit open.
The voltage relay is installed in the apartment electrical panel, but there are models that are plugged into a socket. 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 adjust so that the number of operations is no more than one per month. When the voltage in the network is constantly increased or decreased, it is advisable to install a stabilizer.
Connecting a three-phase voltage relay must be done after the introductory machine, the value of which is chosen one step less, for example, in the ratio of 32 A and 40 A.
The three-phase voltage relay is connected to the current-carrying and neutral wires of the network, as well as to the output contacts of the load connection to monitor their condition. Modes are changed by switching jumpers on the relay terminals. When triggered, its coil is de-energized and opens the power contacts. A winding of a power contactor can be connected to them, which also works, turning offconsumers. After a time delay, when the voltage is restored again, the relay returns to its original state, closing its power contacts.
The above scheme turns off consumers when there is a problem in the network. Protection can also be built on 3 single-phase independent voltage relays. It is used for separate loads on each supply current-carrying wire. Power contactors are usually not used here if the load is not higher than 7 kW. The advantage of this method is that voltage is maintained on the remaining phases when one of them is turned off.
Features of common types of voltage relays
Devices differ in function 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;
- short circuit or phase sequence failure;
- skew or phase failures.
The device also monitors other network parameters and opens the power supply to the load when they deviate from the norm. Three-phase voltage relay RNPP-311 can be configured for two control modes.
- Linear - operation due to phase imbalance, when zero shift is not dangerous for the consumer.
-
Phase - when phase voltage imbalance and zero offset are unacceptable.
three-phase relayrnpp voltage
On the front panel there are indicators for the presence of voltage, load connection and some deviations from the norm. Adjustment is made by six potentiometers. The following parameters are set:
- boundary values of maximum and minimum voltages, as well as the limiting value of phase imbalance;
- Delay of load disconnection in case of accidents;
- delay to connect to the network after the parameters are restored.
The device remains operational when zero and one of the phases or at least two remain active.
Relay RKN-3-15-08
The device is used for the following control methods:
- voltages in phases;
- "sticking" of conductors;
- violations of phase sequence;
- voltage deviations outside the specified range.
Thresholds are set by two potentiometers. The indication allows you to control the voltage, network errors and the operation of the built-in electromagnetic relay. Operating conditions are normal.
The connection diagram of the three-phase voltage relay RKN-3-15-08 practically does not differ from the one given earlier. It only has a simpler setting. The price for this three-phase voltage relay is slightly lower than for RNPP-311. It is about 1500 rubles. Different modifications of both types can differ significantly in cost, it all depends on the functionality.
ASP series appliances
Bin a separate row are fully digital protective relays of the ASP series. In most of them, you can no longer find trimming elements of analog signals. Potentiometers depend on the influence of the external environment, quickly age, denominations change, and contact often disappears.
Digital devices do not contain contact mechanical parts, due to which the effect of external factors is reduced and their reliability is increased. In appearance, the devices are distinguished by a digital display. Their price is on average higher, but you can also find budget items.
Relay ASP-3RMT
The model is basic, and it has all the most necessary functions that a three-phase voltage relay should have. Its price is 2 times lower than other devices with built-in digital voltmeters and screens. If you do not need a display, but need protection, the device is quite suitable for installation.
Relay ASP-3RVN
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 that use electric motors. The device is convenient in that it allows you to control the voltage at each phase on the display, as well as monitor its asymmetry. The built-in memory powered by an independent source makes it possible to remember the parameters and the number of emergency shutdowns with the possibility of displaying them on the screen. This does not require any special setup skills. Additional functions are available through the control buttons.
The ASP-3RVN device is connected to the network in parallel with the load, similar to the schemes presented earlier. The device monitors the current mains voltage. In the event of an accident, its contacts are opened, which are included in the open circuit of the starter winding. After connecting and applying power, the protection relay checks for the presence of voltage. This is indicated by three LEDs. In case of violation of the phase sequence or sticking, dashes (--) are displayed on the indicator. Further, the measured phase voltages are displayed on the screen with an interval of several seconds. At the same time, the corresponding LEDs light up.
When an accident occurs, the causes of its occurrence are displayed on the screen. The settings are initially factory, but they can be changed by pressing the appropriate buttons. If errors appear during installation, they can be reset and reset to factory settings with the touch of a button. All settings are stored in memory and can be checked.
ABB monitoring relay
One of the well-known devices for protecting electrical equipment is the three-phase voltage relay ABB. The device has established itself as one of the most reliable in case of voltage imbalance. For three-phase networks, the ABB SQZ3 device has been developed, withstanding voltages up to 400 V. A large assortment allows you to choose the right model for certain working conditions. The device allows you to control:
- mains voltage with load disconnection in case of emergency;
-
skew, loss and correct phase sequence with signals in case of deviations.
voltage relay three-phase abb
ABV has established itself as a reliable supplier of high quality, easy to use and versatile electrical equipment.
Conclusion
A three-phase voltage control relay is a necessary part of the power supply system for appliances. It will reliably protect the electrical network of an apartment or house, as well as expensive electronics from power surges and distortions.
