CHAPTER 2:SWITCH

DJM 3052: INDUSTRIAL ELECTRONICDEM3A

PN NURUL NADIAH BT SHAHROM

Course Learning OutcomesCLO1:

Explain the functions and operational principle of switch, relay, solenoid, electronic control devices, thyristor, converter, sensor and telemetry system.(A3)

CLO2:Display types of switches, electronic control devices, converters and sensors according to operational principle.(P4)

CLO3:Apply the switches, relay, solenoid, electronic control devices, thyristor, converter and sensors in various circuit.(C3)

Introduction

• The switch is a mechanical, electrical or electronic device that opens or close a circuit. Switching may also be called making or breaking the circuit.

• List and describe 4 types of switch used in industries.

Types of switch

Push button

Limit

SlideRocker

Precision

Toggle

Push button

• A pushbutton is a switch activated by finger pressure. Two or more contacts open or close when the button is depressed. Pushbuttons are usually spring loaded so as to return to their normal position when pressure is removed.

Limit switch

• A limit switch is a low-power snap-action device that opens or closes a contact, depending upon the position of mechanical part. Other limit switches are sensitive to pressure, temperature, liquid level, direction of rotation and so on.

Slide switch

• A slide switch is a switch activated by sliding of two or more contacts open or close when the button is depressed. Pushbutton are usually spring loaded so as to return to their normal position when pressure is removed.

Rocker switch• A rocker switch is a switch activated by 3 finger

which includes 2 finger push button for opening and closing of 2 circuits. Two contacts open or close for 2 circuits when the button are pressed and depressed. Pushbutton are usually spring loaded in the bottom to return to their normal position when pressure is removed.

Precision switch• A precision switch is a switch activated by roller

loaded on the top of pushbutton to open or close a circuit. Only one contact open or close when the button is depressed by load moving on top of the roller. Pushbutton are usually spring loaded so as to return to their normal position when load on top of roller is removed.

Toggle switch

• A toggle switch is a switch activated by ball bearing moving for open or close a circuit. The movement of roller makes a contact to open or close a circuit when the toggle is depressed. A toggle usually parallel with the force loaded so as to open or close.

• List four aspects that we need to consider in selecting switch.

Selecting switch

Design of power circuits

Protection of power devices

Determination of the control

strategy

Design of logic and gating

circuits

National Electrical Manufacturers Association

Question 1

• Which of these switches are manually actuated by a mechanical lever, handle or rocking mechanisma) Rotary switchb) Pressure switchc) Limit switchd) Toggle switch

Question 2

• Which of these switches are most commonly found in equipment that has the capability of operating in more than one mode– Toggle switch– Limit switch– Rotary switch– Pressure switch

Question 3

• Limit switch can be use as– Drive press– Actuator lever– Wooden rocking actuator– All above

Question 4

• From the suitable diagram, explain the basic function of the switch (during On and OFF).

+

Switch

_

+

L

+

_

+

L

Bulb is OFF, no current flow. Bulb is ON, current flow.

Switch

• Describe the basic operation of FIVE (5) types of switches stated below:– Push button switch– Limit switch– Slide switch– Toggle switch– Precision switch