A two-way switch (bipolar) also applies to electrical switching devices, as does a regular (single-pole) switch. But if the latter only allows you to break or connect the electrical circuit, then the switches can operate with several connections. The figure below clearly shows their main differences.
The figure shows:
- ordinary switch and its connection option;
- example of using a double switch;
- connection of a bipolar switch;
- switch.
Note that the switches can be in two or more directions, for example, four-pole or power three-phase. It makes sense to talk about the latter in more detail.
Content
- Three Phase Switches
- Modular Multiposition Switches
- Household use
- How to connect
Three Phase Switches
Three-phase power switches are widely used in control circuits of powerful asynchronous electric motors, their purpose is to switch the winding from a "star" to a "triangle". This implementation can significantly reduce the starting current. The figure shows a diagram of such a connection.
Designations in the diagram:
- A, B, C - phase nutrition;
- C1, C2, C3, C4, C5, C6 - outputs of the motor windings;
- SA is a three-pole power switch.
The motor starts when its windings are connected by a "star", when entering the normal mode, switching to the "triangle" is carried out.
Modular Multiposition Switches
Cam packet switch - the most common type of data devices, like other switches, it is used to control various types of electrical loads.
The scope of cam switches is quite extensive, here are a few examples of their use:
- switchboards for AC and DC control;
- systems of emergency shutdown, automatic input of a reserve, switching of operating modes of electric motors;
- control of transformer substations and lighting;
- equipment for substations (control of grounding conductors, sectional switches, disconnectors, etc.);
- switching modes of heating equipment (switching on, off, switching electric heating elements of the load);
- selection of the operating mode of electric welding equipment, etc.
Cam switches consist of several packages (each of which is responsible for switching one line), placed in one housing. The figure below shows the design of such a package.
Designations in the figure:
- a - fixed contacts (4 pcs.) to which the wires are connected;
- b - a special protrusion of the "fist", which allows you to hold and move the rod;
- c - group of mobile contacts (in this type there are two of them);
- d - two guide grooves (allow the stem to make translational movements);
- e - two rods coated with an insulating sheath;
- f - contacts (8 pcs.), usually made of an alloy containing silver;
- g is the packet;
- h - two threaded rods (fix the package and the cover);
- I is the rotor;
- J - four springs (return the rod to the closed position);
- k - shaft connecting the handle to the rotor;
- l - four screws for clamping cable wires.
Note that the package switch (cam switch) can be in several positions, including zero, that is, when the contacts are disconnected. The figure shows the state of the switch in the neutral position.
Note that all the main characteristics of the switches are indicated on the device case, there are displayed:
- type of switch;
- rated current for which the switch is designed;
- circuit diagram and switching table;
- protection class.
The diagram and switching table shown on the SPAMEL rotational direction switch housing are shown below.
Thanks to such a table, it is clearly visible in which position, which groups of contacts are connected.
Household use
Switches are not so often used in everyday life as switches, but, nevertheless, there are tasks in which it is impossible to do without them. For example, when you need to control lighting from different places. Switches can be installed at the entrance to the room and near the bed (so as not to go up to turn off the lights) or at different ends of a long corridor.
The implementation of such a control scheme is quite simple, its image is shown in the figure below.
Designations in the figure:
- A, B - switches;
- L - lighting device.
If it is necessary to control lighting from more places, the circuit can be slightly complicated by adding an intermediate switch to it.
Designations in the figure:
- A, B - on-off switches;
- C - intermediate double switch of two directions;
- L1 - a lighting device.
Note that taking this scheme as a basis, you can control the lighting from three or more places. To do this, just add the necessary number of intermediate switches to it, they are connected in the same way as device “C” in the above diagram.
How to connect
Here is an example of implementing a lighting control circuit from two places, using the Legrand switches for this. This manufacturer produces reliable household models of the Cariva and Valena series, the price of which is not much different from the cost of conventional switches.
Before you buy the switches, pay attention to the different designs, they can be for hidden or open wiring, as well as with backlight and position indication on the box (case).
We remind you that all work related to the connection of electrical equipment must be performed only with a complete blackout of electrical circuits. Therefore, before proceeding, make sure that the electricity is turned off, it is advisable to use a special device (probe) for this.
A schematic implementation of the task is shown in the figure below.
Blue indicates the neutral wire, red indicates the phase. Note that all switching must be done exactly with the phase.
How a single-key switch is connected is visible in the bottom figure.
Connecting switches for control from three places is as follows.
As you can see, a one-key or two-key switch in two directions is not difficult to connect, while it helps to make lighting control in your apartment more comfortable.
