Direct and Indirect Control Module 2 Direct and Indirect Control

Module Objectives 1- Configure and connect the electrically actuated directional control valves (solenoid valves). 2- Configure the direct control in electro-pneumatics. 3- Configure the indirect control in electro-pneumatics. 4- Identify the advantages and disadvantages of direct and indirect control techniques. 5- Simulate and construct simple electric circuits

Module Contents 1. Solenoid valves 2. Types of solenoid valves 3. Direct control in electro-pneumatics 4. Advantages of direct control 5. Disadvantages of direct control 6. Practical task 1 7. Practical task 2 8. Indirect control in electro-pneumatics 9. Advantages of direct control 10. Disadvantages of direct control 11. Practical task 3

Electrically-actuated DCV - Solenoid valves Forms of energies used to operate electro-pneumatic control system are: Electrical energy. Compressed air energy Electrically actuated (DCVs) are switched with the aid of an electric coil that is called a solenoid. The electric coil attracts or repels the valve spool

Operation Activated Not Activated

Solenoid valves groups Single solenoid valve with a spring return Double solenoid valves keeps and maintains the last switched position even when no current flows through the solenoid. Memory Valve

Direct control in electro-pneumatics It is the control of an electro-pneumatic valve without using intermediate components such as a relay, a contactor or an industrial computer (PLC). Advantages of direct control Simple and easy Cheap. Disadvantages of direct control Remote control is not possible. Switching more than one valve at a time is not possible. Latching is not possible. Design improvement is not flexible.

Direct control in electro-pneumatics It is the control of an electro-pneumatic valve without using intermediate components such as a relay, a contactor or an industrial computer (PLC). (See the figure)

Practical Task 1 Direct control of a double acting cylinder using 5/2 DCV, single solenoid. Objectives: to be familiar with: 5/2 DCV, single solenoid, with spring return. Electro-pneumatic equipment.

Background A direct control circuit is used to control a 5/2 DCV single solenoid using a push button switch. Activating the pushbutton will energize the coil (solenoid) which in turn will actuate (operate) the valve.

Solution to Practical Task 1 Required components A double–acting cylinder A 5/2 way valve, single solenoid A power supply A push button switches

Practical Task 2 Opening/closing the flow in a pipeline The double acting cylinder (1A) in the Figure is used to open and close the main valve in a pipeline. Draw an electro-pneumatic circuit to control the movement of cylinder (1A).

Solution-1 to Practical Task 2 with a double acting cylinder

Solution-2 to Practical Task 2 with a double acting cylinder Required components with a double acting cylinder: Double – acting cylinder 5/2 way valve, double solenoid Power supply Switches

Class work (1) 3. Draw a pneumatic and an electric circuit to control a double solenoid valve directly, by using a normally closed detent switch.

Practical Task 3 Direct control of a double acting cylinder by using 5/2 DCV, double solenoid Objectives: to be familiar with: 5/2 DCV, double solenoid. Electro-pneumatic components. Electric circuits

Practical Task 3 Diverting machine The parts used in the diverting machine are to be moved from one conveyor track to another. By pressing a pushbutton switch the frame of the diverting machine is pushed forward. The part is moved over and transported onwards in the opposite direction. By pressing another pushbutton switch the frame is returned to its start position as shown below.

Solution to Practical Task 3

Indirect control in electro pneumatics Indirect control is the control of an electro-pneumatic valve using intermediate components such as relays, contactors or programmable logic controllers (PLC).

Advantages of indirect control systems Remote control is possible Switching more than one valve at a time is possible Latching is possible. Flexible design improvement and development. Incorporating logic operating conditions (OR, AND conditions)

Disadvantages of indirect control Complicated More wiring More cost involved

Practical Task 3 (Bulk material) Problem description: Bulk material is to be emptied from a hopper as shown in the Fig. By pressing a pushbutton switch, the hopper is opened and the bulk material is emptied out. By pressing another pushbutton switch the hopper is closed again. Hint: The controlling circuit should contain relays for the indirect control

Solution to Practical 3

Solution to Practical 3

Solution to Practical 3

Homework 2

Homework 2 Solution 1

Homework 2 Solution 1

HW 2 Solution 2

HW 2 Solution 2

End of Module 2