FOUR-STATE RELAYS AND MULTIPLE CONTROL POINTS (THEORY)
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Welcome to the home’s electrical systems course by NPR Online Technologies!
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In this theoretical lesson we will see how to use a four-state relay to control two lamps or two groups of lamps from an arbitrary number of locations.
The relay system analyzed in the previous theoretical lesson is based on a single control point. However, it can be easily extended to several control points by inserting more push-buttons, as shown in the following circuit diagram, where there are two push-buttons and the dots indicate the possibility of inserting other push-buttons according to the requirements of the electrical system design.
We can observe that to insert additional buttons, it is sufficient to connect them in parallel, so that one of the terminals is connected to the hot wire,
and the other terminal is connected to the relay coil.
Well, with this simple consideration we get the final circuit:
We are also ready to install this circuit inside a room, assuming it has three entrances.
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Let’s start with the junction box, where we can find the hot and neutral wires.
In this junction box, we can place our relay.
Then we can prepare the electric boxes where we will place the three push-buttons. We can see that they are located close to the room entrances.
We can then proceed with the positioning of the bulbs.
Once the position of the various system components has been established, we can lay the electrical pipes that will be used to make the electrical connections between the various components.
We are therefore ready to make the electrical connections.
Let’s start by connecting the neutral wire to one of the relay coil terminals.
According to the wiring diagram, we then connect the hot wire to the two relay switches.
We now prepare a connection to the second terminal of the relay coil.
Let’s proceed by making the connections with the first button by passing the wires through the first electrical conduit.
In particular, we connect one terminal of the button to the hot wire and the other terminal of the button to the coil of the relay.
Using electrical conduit number two, we make the same connections for the second button as well.
We use the same procedure for the third button as well.
We can now move on to connecting the bulbs using the electrical conduit number 3.
We connect one terminal of the bulbs to the neutral conductor.
And finally we connect the other terminal of the bulbs to the two relay switches.
With this last operation the connection procedure is completed.
Well, we have also come to the end of this lesson dedicated to the to use of a four-state relay to control two lamps or two groups of lamps from an arbitrary number of locations.
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