Electricity sources are not absolutely reliable and sometimes turn off, which leads to a negative impact on consumer facilities. This is unacceptable for critical devices, so they are powered by two or more additional sources. When they are connected, ATS devices are used. What it is, explains the decoding of the abbreviation - "automatic input of the reserve." It is a way to create an uninterrupted power supply to the consumer with two or more power inputs. This is ensured by automatic connection of the backup input in case of loss of the main one.
Both power supplies can be connected at the same time. The disadvantages of this method are high short circuit currents, high losses and complexity of network protection. The input of the reserve is usually carried out using a switching device that turns off the main power source. The reserve power must match the loads. If it is not enough, only the most important consumers are connected.
ATS requirements
- Fast transfer of reserve after relay operationvoltage.
- Turn on in any case during power failure, except for short circuits.
- No response to voltage drops when starting powerful loads at the consumer.
- Single actuation.
Classification
Devices are divided according to the principle of operation.
- Single-sided. The scheme contains two sections: power supply and reserve. The latter is connected when the main voltage is lost.
- Double-sided. Any of the lines can be both working and reserve.
- Recovering ATS. When the main power is restored, the previous circuit is automatically put into operation, and the backup circuit is turned off.
- No automatic recovery. The operation mode with the main power supply is set manually.
ATS operation principle
In low-voltage networks, it is convenient to use special relays that control voltage in protection circuits (ATS circuits, etc.). ATS is preferable here, since not all equipment is able to withstand frequent switching of power supply. What does AVR look like? What is it and how does it work? This device is clearly visible in any simple diagram.
- Relay EL-11 controls the three-phase voltage, monitors the phase imbalance, their breakage and alternation.
- Electromagnetic relays with powerful contacts are used to connect loads. In normal mode, the coil of the magnetic starter of the main input is powered from it and with its contacts KM 1 connects the power supply to the load.
- When the voltage in the main circuit disappears, relay KM 1 turns off and power is supplied to the coil of relay KM 2, which connects the backup input.
This ATS scheme can be used in private homes, industrial and administrative buildings, where the switched load reaches tens of kilowatts. The disadvantage of the circuit is the difficulty of choosing a relay for high currents. It is still suitable for switching low-power consumers, but for heavy loads it is better to take an ATS starter or a triac.
Indispensable sources of additional power are gasoline or diesel generators. The latter have found wide application due to their economy and greater power. The market offers a wide range of diesel generator sets (DGS) containing high overload protection systems.
ATS operation
How does ATS work? What is it in terms of reliability in the supply of electricity to consumers? Devices are divided into 3 categories. The electricity supply of housing is among the lowest. With frequent power failures, it is better to install a reserve in the house, since the durability of household appliances, as well as comfortable living conditions, depend on this. Uninterruptible batteries are installed in apartments, which are mainly used for electronic equipment. Generators are most common as standby power sources for private homes.
The simplest version of a gasoline generator is connected to the power supply of the house through a changeover switch. This prevents a short circuit in the event of an erroneous input of the reserve, when the automatic power supplies to the house are not turned off. The switch is selected with three positions, where the middle of them completely cuts off electricity.
Do-it-yourself ATS can be installed in automatic mode if you equip the generator with an automatic starting device and control it from the cabinet using contactors that also switch inputs. Automation works on microprocessor control, for example, on Easy relay controllers. Voltage sensors are used to enter the ATS reserve. As soon as the power is turned off, the generator engine starts immediately. It takes some time to reach the operating mode, after which the ATS switches the load to the reserve. Such delays are acceptable for domestic needs.
Auto Generator Start Unit (BAG)
ATS - a private house system that provides start-up and control of a backup generator in the event of a power failure. The latter is equipped with a special BAZG unit, which is an inexpensive solution for power failures in the main network. It makes five attempts to start within 5 seconds in each interval after the voltage on the main input disappears. In addition, it controls the air damper, closing it at the time of launch.
If the voltage returns to the main input, the device switches the load back and stops the generator engine. When the generator is idle, the fuel supply is blocked by an electromagneticvalve.
Features of ATS operation of a private house
The most common way is with two inputs, where the first input takes precedence. When connected to the network, household loads mostly operate on one phase. When it disappears, it is not always convenient to connect the generator. It is enough to connect another line as a backup. With a three-phase input, the power is controlled by a relay on each of the phases. When the voltage goes out of range, the phase contactor turns off, and the house is powered by the two remaining phases. If another line fails, the entire load is redistributed to one phase.
For a small cottage or cottage, a DGU with a power of no more than 10 kW is used for a shield operating at 25 kW. Such a generator is quite enough to provide the house with the necessary minimum of electricity for a short time. In the event of an emergency, the voltage control relay switches the consumer bus to backup power and gives a signal to start the diesel generator set. When the main power is restored, the relay switches to it, after which the generator stops.
Extension of ATS functions
Programmable logic controllers (PLCs) are used to control circuit breakers according to selected algorithms. They already contain the ATS program, which only needs to be configured to implement a particular mode of operation. The use of a PLC, such as the AC500 controller, makes it possible to simplify electrical circuits, although at first glance the device seems complicated. ATS control can be placed on the switchboard doorin the form of a set of switches, buttons and indications.
The software is already included in the typical solution. It is installed in the PLC.
Conclusion
Power failures can lead to various negative effects on consumers. Most users have only a vague idea about ATS. What it is, many do not know at all and take products that are designed for completely different purposes as a device. Due to the high costs of electrical equipment, it is important to choose the right transfer switch. This requires expert advice. ATS allows you to increase the performance of household appliances and objects for which a constant power supply is important.
