For the organization of backup power in private homes and enterprises set generators. This is due to the need, especially in winter, to have an uninterrupted supply of electricity, since most modern heating systems are equipped with electronics, without which they do not function.
The generators are switched by connecting them parallel to the central power line through a special switch that excludes parallel switching.
Rocker switch: principle of operation
An electric type apparatus, which serves to disconnect an electric load from one energy source and connect it to another source, is called a cross over switch, or a cross over type switch (midpoint switch). Devices can be with or without arrester. In the first case, network switching can occur when the load is fully connected. In the second - only when it is turned off.
The circuit breaker is operated manually, that is, if it is necessary to switch the power supply sources, the operator acts on the insulated switch control lever. There are also automatic switching systems.
Circuit-breaker circuit
The toggle switch consists of a housing, knife-type movable contacts fixed to the shaft, stationary contacts, a control handle, an arcing chamber (if one is present) and terminals for connecting to the line. The device has two operating positions (contacts 1 and 2) and one neutral (intermediate), in which the load is not connected to any of the lines.
A simple connection diagram for two power sources and one load line looks like this: for contacts 1, for example, a central power supply is connected, for contacts 2 - a diesel or other type of electric generator. The most common switches are four-pole and two-pole switches.
The connection of the cross over switch in case of input of three-phase voltage into the building is as follows:
- the switch must be at four poles;
- four terminals go to network input;
- four terminals go to the input of the generator;
- the load is connected to the four terminals.
Three of the four terminals go into phases, one to zero.
Specifications
The main characteristics of the cross over switch are:
- The rated current that it can pass. Devices release at 15.0, 25.0, 32.0, 40.0, 63.0, 80.0, 100.0 and 125.0 A.
- Thermal current that does not destroy elements.
- Permissible mains voltage.
- Short-term surge voltage that the insulation can withstand.
- The number of poles that the cross over switch is capable of simultaneously switching.
- The wear resistance of electrical contacts is determined by the operating voltage and the magnitude of the transmitted current.
- The wear resistance of mechanical elements is determined by the number of switching cycles.
Toggle Switch Modifications
Two-way circuit breakers are used to work in single-phase circuits. Such switches are equipped with through-type capacitors. There are two and three-module execution. Paired with a cross over switch, a power supply unit designed for a voltage of up to 300 volts can work. Such a switch is installed in the switchboards of various types. When used with a generator, the permissible voltage must not exceed 350 volts. For the load, the average indicator of the transmitted current is 30 amperes.
Three-way circuit breakers are based on expansion switches. Most often they are used for two-phase type circuits and installed in industrial enterprises. Switches of this kind may have locks. Typically, three-way circuit breakers have a high sensitivity threshold. The devices are also equipped with a protection system.
Cross over type circuit breaker
All of the above rocker switches have one drawback - they require the presence of a person to carry out manipulations with switching circuits. This is inconvenient, especially when the central power supply disappears frequently and unpredictably. Therefore, a circuit-breaker is designed . More precisely, this is a whole block called automatic reserve input (ABP).
ABP is a complex design, but craftsmen assemble such systems from relatively inexpensive relay devices (contactors). Apply for this model with normally closed and open contacts.
When using a home-made rocker switch, the wiring diagram works according to a certain principle. For example, in the line there is electricity of the central supply, then a relay with normally open contacts closes the circuit with the load. The relay with normally closed contacts to which the generator is connected is open in this case. As soon as the current disappears, the combination is reversed, and the network begins to power the generator.
Conclusion
The use of change-over switches for switching the generator is a reasonable solution that allows you to have significant advantages. In addition to facilitating the maintenance process of an individual power source, this device makes it possible to control the state of network functioning and ensures the safe operation of all elements included in the line. To select the optimal variant of the cross over switch, they are primarily guided by the individual characteristics of the electric network and the devices included in it. Based on this, a cross over switch is selected with characteristics that satisfy such requirements.