ELECTROPNEUMATIC CONTROL EXERCISES
1. Electric bell
In a company an electric bell is used as signal to tell the staff that it is time to start work, go for tea break, go for lunch and go home. A switch is used to activate the bell. The bell rings when the switch is pressed. It will go off when the switch is released.
2. Indication Lamp
In a plant an indicating lamp will be lighted n when the pressure and the temperature rise above a certain level. These two conditions are simulated by using push button switches PB1 and PB2.In other words when both PB1 and PB2 are pressed, the lamp will be lighted. When either one of them is released, the lamp will go off.
3. Production line indication lamp
In a production line, an indication lamp will be lighted whenever an operator presses a push button. This is to capture the attention of the line leader whenever they encounter a problem. Here, three stations are simulated using push button switches PB1, PB2 and PB3 respectively
4. Burglar alarm
In an electrical parts warehouse, a normally closed limit switch is used to send a signal to the burglar alarm when the door is opened. The alarm will not sound if the door is closed. The burglar alarm system is activated or deactivated by a key selector switch
5. Cutter
In a printing firm, a cutter is used to cut the side edges of the papers. This cutter is controlled by a pneumatic cylinder. For the safety of the operator, the cutter will move down only when both the push button switches PB1 and PB2 are pressed and also a safety cover must be closed. The safety cover is closed manually and a limit switch is used to detect the closed position. When one of the push button is released or when the safety cover is opened, the cutter will immediately return to its top position. The cylinder is controlled by a single solenoid spring return valve
6. Bus door
The opening and closing of a door (Similar to bus door) is activated by using two push button switches PB1 and PB2.Switch PB1 is for opening and PB2 is for closing of the door
The cylinder is controlled by
- A double solenoid valve
- A single solenoid spring return valve
7. Huge steel door
A huge steel door is installed in a deep mining tunnel. This door may be opened or closed by two sets of push button switches. One set from inside and the other from set from outside. The sliding unit is controlled by a double solenoid valve
There are two control methods being used namely:
a) Direct control
- Indirect control
Condition: Signal ‘open’ should be given priority over ‘close’
8 . Magazine feeder
By pressing a start button (With the cylinder initially retracted), a Work piece is pushed away from the gravity feed magazine onto a Conveyor system. The cylinder returns automatically when it has reached the fully extended position. Fully extended and retracted positions are sensed by limit switches Ls1 and Ls2.The cylinder is controlled by a single solenoid spring return Valve.
9. Stirring motor
A stirring motor is used to stir the mixture of liquids in the tank. On pressing the start button, the stirring motor starts rotating. It stops automatically after a time delay of 20 seconds.A stop button can be used to stop the motor before the time delay elapsed
10.Liquid dispenser
When sensor S1 senses a container,a pneumatic operated valve will be opened to allow liquid to flow from the tank into it.The valve close automatically after a time delay of 5 seconds,after which the container will be transported to another station.For safety reasons, the valve closes immediately when the container is removed,even before the time delay starts,that is when sensor S1 is triggered.The valve is controlled by a rotary actuator which is activated by a single solenoid spring return valve.Design and build the circuit to meet the above criteria.
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