Download Understanding Switches: Classification, Identification, and Installation and more Study Guides, Projects, Research Electronics in PDF only on Docsity! Installing Switches Description: This learning element deals the different classification of switches, types and installation procedures of commonly used switches. Identifying switches an their uses 1. A switch is a device used for changing the course (or flow) of a circuit. It may turn ON or OFF a certain load connected to it by cutting the path of current. 2. When the switch is open, the current cannot pass through the circuit because the path of current is open. 3. When the switch is closed, the current can pass through the circuit because the path of current is close. 4. There are four classification of switch. 4..a Single pole single throw (SPST). A simple on- off switch: The two terminals are either connected together or not connected to anything. An example is a light switch. Information Sheet 01 Identifying terminals of 3-way and four- way switch 1. These switches are externally similar to normal, single-pole switches, but have extra connections which allow, in effect, two circuits to be controlled, which can be thought of as the "on" circuit and the "off" circuit. 2. Electrically, a three-way switch is a single-pole, double-throw (SPDT) switch: Toggling the switch disconnects one circuit and connects the other. (Common terminal (C) positions the switch to either circuit) Position 1 Position 2 3. The figure shows a locally available 3-way switch. The top terminal is a common terminal which is marked 0; the other terminals are marked 1 and 3. 4. Initially, the common terminal 0 is connected to terminal 3. Terminal 1 and 3 are called traveler terminals which can be interchangeably connected. 5. Upon depressing the seesaw, the common terminal 0 will eventually disconnects to terminal 3, thereby connecting to terminal 1. 6. Three-way switches make it possible to control a light from two locations, such as the top and bottom of a stairway. 7. By connecting two of these switches together back-to-back, it can be arranged that toggling either switch changes the state of the light from off to on, or on to off. Figure A shows the “ON” position of the circuit Fig. A. The circuit is “ON” 8. Pressing the switch to the left will turn “OFF” the circuit. (Suppose this switch is located at the bottom of the stairway and the switch to the right is at the top.) Fig. B. The circuit is “OFF” 9. Pressing the switch right will again turn “ON” the circuit. Fig. C. The circuit is “ON” 10.Pressing again the switch to the left, the circuit will turn “OFF”. Fig. D. The circuit is “OFF” 11.Four-way switch is a DPDT switch internally wired for polarity- reversal applications: only four rather than six wires are brought outside the switch housing; 12.The figure shows a locally available 4-way switch. The terminals are marked 1, 2, 3 and 4. 13.Initially, terminals 1 and 2 are connected, so with the terminals 3 and 4. 14.Depressing the seesaw of the switch will make the connection between 1 & 2 and 3 & 4 cut; shifting the connection to 1 to 4 and 3 to 2. 1. By connecting one or more four- way switches in-line with three- way switches at either end, the light can be controlled from three or more locations. Toggling any switch changes the state of the light from OFF to ON, or ON to OFF: The figure shows that the lamp is OFF. 2. Pressing the three way switch to the left changes the state of lamp from OFF to ON 3. Then by pressing the four-way switch turns OFF the lamp. 4. Pressing the three-way switch to the right turns the lamp ON again. 5. Pressing again the left three-way switch turns OFF the lamp. 6. Just add another four-way switch between three-way switches to control the lamp in four or more locations as shown in the figure.
