Voltage relays are an everyday concept used by the Internet to designate devices of a voltage control relay class. Consider today the variety, characteristics, as a first approximation, the design of products of this kind.
Purpose of the voltage relay
According to the legislation on the supply of electricity is a contract. The text( and GOST) prescribes the values, the limits of the parameters. The consumer has the right to demand compliance with the terms of the contract, sue. He has the right, but he will have rights, who has more rights. Therefore, voltage relays are popular in some areas of Russia.
Simplified abbreviation for devices. Purpose - to control the main parameter of the network. Voltage greatly deviates from the norm, there is a disconnection of the consumer. In Western countries, the question is not about protection, contracts are strictly enforced.
So, now we know: in the case of excess, the voltage relay will turn off the equipment, how it differs from other devices: uninterruptible power supplies, stabilizers. Relays are cheap. Coil of copper wire with an anchor, the force opening is designed for a number of specified conditions. Uninterruptible power supplies include batteries, voltage regulators are built on the basis of powerful transformers, whole electronic conglomerates. An ordinary user delights to anything. Let's list the features in a single list, explain the need to use a voltage relay:
- The relay can optionally operate with a large load. Since the switchings occur in abnormal mode, the current is high without damage to durability. Stabilizers, in particular, uninterruptible power supplies have limited capabilities. Knows any user of the personal computer.
- The relays are silent, other devices are loud. Visible at night. If they reconcile with uninterruptible power supply sources, clicks of transformers are perceptible, most importantly, they can sound continuously when the voltage of the network is unstable.
- Voltage monitoring relays are executed in a convenient package designed for mounting on a DIN rail in a switchboard. Simplifies the process of operation, because it makes it possible to centrally protect the apartment immediately. At the same time, it will not be possible to install an uninterruptible power supply or stabilizer so simply.
The advantages of protection relays include a certain amount of automation. Typical samples allow you to set the on delay in case of voltage variations in the network in the threshold region. Depending on the level of intelligence of the equipment, the algorithm in each case will be different. Manufacturers provide the user with the possibility of forced inclusion. The voltage dropped or rose above the norm, but if it returned quickly to a fixed value, no need to wait for the built-in timer to work. The need for a forced start occurs when you first turn on, the equipment does not distinguish the mode from an emergency situation.
Voltage relays are small, relatively cheap and easy way to protect your equipment from the vagaries of the network. Failure to function - with certain devices, electricity consumers easily fail. On the Internet, the topic of "burning out" of the neutral wire is extinguished. We suppose that none of the readers encountered such a dilemma in practice, the point is: if the said conductor is broken, the voltage of neighboring phases between the apartments of a typical residential building turns out to be attached to household appliances.
The illustration illustrates the case. The house is supplied with a network of three phases, the voltage relative to the earth is 230 volts. Between them falls 400 volts. A typical scheme of electricity supply, breaks the neutral wire below the switchboard on the site, 400 volts are applied between neighboring apartments. When neighboring devices have the same resistance, consuming a comparable current, the voltage will share equally. Not difficult to notice: as a result, each will be 190 volts. Below the norm, in most cases there is no immediate threat. An accident will be noticed, eliminated, as the opportunity presents itself.
Another thing, the current consumption differs significantly. A voltage divider with unequal shoulders is formed, and in the worst case, a little less than 400 volts can get to the load of the apartment. It is clear that this situation is dangerous for most of the equipment. On Youtube illustrate with the help of video, where the incandescent bulb burns. It is useful relay voltage, power off. For each three phases, you can put two devices, one apartment can save.
Are situations valid? A zero break looks wild, it is easier to turn on control devices at the entrance to the equipment at home that would shut down the entrance in case of malfunctions. Apartment owners have nothing to worry about. But is there such equipment in the house? Find out! It will not be easy, given the level of awareness of our electricians.
Varieties of voltage relays
Readers are now interested in monitoring the parameters of the electrical network at home. At first glance, it is easy to organize how to protect the entrance, the building as a whole. It is enough to measure the currents of each of the phases and the neutral conductor. In the event of a break of the last part of the electrons rush between the apartments, bypassing the local land( neutral).The current will flow between the two phases.
A typical picture for three-phase circuitry, alien to the average person: do not need land? Yes - not needed! In three-phase circuits with an isolated neutral there is no earth. Explorer is not needed for the operation of the circuit. At the substation the local accident of the building will not be noticed.
The phase currents are normally folded to neutral. Parameters are easy to control, in case of a difference, take action. What devices monitor the situation? Headache of management companies, not residents of apartments. Another thing, in some cases, will require the collection of money to upgrade equipment.
From what has been said you need to understand, you should not always attack the nearest electrician store to buy a voltage relay. For the most part, the devices are intended for summer residents, garage cooperatives, because of the peculiarities of the operation of the jumps, the sinking of the voltage is palpable. According to the applicability of the relay is divided into the following categories:
- Single-phase AC voltage relay. Devices discussed above.
- Three-phase AC voltage relay:
- For circuits with insulated neutral. Apply relays at 380( 400) volts. Often the illustrations are schemas "star", easier to understand. Relays of the specified type are used for systems with insulated neutral. The concept of land does not exist. Currents flow only between the phase conductors.
- For circuits with grounded neutral. Sometimes the prefix is added-deafly. Residential buildings are being electrified, consumers are divided into three phases, each one comes in one piece. Three-phase relay will protect all equipment. Line voltage loss is monitored, parameters are exceeded for permissible limits. Please note that there is 230 volts on each line, relays of the appropriate type are used.
- DC and AC voltage relays allow you to control a given level. The combined solution in some cases may be more profitable. AC and DC voltage can be monitored.
- Relay voltage control for other networks. In industry there are many denominations, for each produced control devices. For ordinary users, the relay family is of no interest.
Parameters of the voltage control relay
When choosing equipment, everyone will have to face the problem of choice. Here are briefly the main parameters of the voltage relay:
- The main characteristics are the upper and lower thresholds for disconnecting equipment from the network. Borders are flexibly set by adjustment, asymmetry is possible. Specific numbers dictate the equipment used. In the passport of the device provide information about the maximum permissible voltages. Information needs to be guided, adjusting the equipment. The three-phase relay often has the ability to set the boundaries of each branch separately. It is convenient when supplying electricity to a private household.
- The type of instrument must match the network in use. The parameters are selected according to the protected equipment. A breakdown can cause a phase failure of the 400 volt network, the relay should turn off the power at once along all lines.
- An important characteristic is the hull design and operating features. Execution for installation on a DIN rail switchboard popular today.
- The reclosing delay is adjustable within a second to tens of minutes. Exhibited in accordance with the features of the equipment operated. Re-enable produce with some voltage margin, the effect is called hysteresis. Most products allow a forced start.
- The design of most voltage control relays includes a protective varistor. Elements are used to shunt the current in emergency situations. With a sharp increase in voltage, the resistance of the varistor drops sharply, the energy is quenched, converted into heat. The characteristics indicate the specific value in j( joules), the pulse current. The average man will hardly be able to measure the characteristics of the jumps, so it remains to rely on the manufacturer's thriftiness.
- The response speed is described in two ways: in the operating mode, one value, in the emergency mode( large deviation) - the other, smaller one.
We talk a lot about parameters of three-phase voltage relays. Knowledge is required for a small fraction of readers. The upper and lower tripping thresholds are set independently for the phases. The following options are present:
- Phase presence monitoring is a critical requirement for certain types of equipment containing motors. With the loss of voltage on one line of consumers fail.
- Phase rotation control is important for proper engine operation. Some voltage relays have an integrated option for parameter tracking.
- A neutral break control was discussed above. By phase imbalance, the relay can indirectly track faults.
The control of “sticking” of phases implies tracking the occurrence of a short circuit along any two lines. In the powerful networks can go unnoticed, the expense of electricity supplier companies will come tangible.