Electrical Controls for Fluid Power Systems

Chapter: 14

Electrical Controls for Fluid Power Systems

(Electrohydraulic & Electropneumatic Circuits)

"Always design a thing by considering it in its next larger context--a chair in a room, a room in a house, a house in an environment in a city plan."

- Eliel Soorinen

"In wisdom gathered over time I have found that every experience is a form of exploration."

- Ansel Adams

"Weakness of attitude becomes weakness of character."

- Albert Einstein

Learning Objectives

While reading and after studying this chapter, you will be able to:

• Identify and understand the function of the various electrical control devices used in the fluid power systems.

• Explain the operating principle of an electrically operated relay switch used in an electrohydraulic system.

• Understand and construct the electrical ladder diagrams.

• Interrelate the operation of electrical ladder diagrams with the corresponding hydraulic circuits.

INTRODUCTION

Nowadays, the focus has been shifted from manual control to electrical control of fluid power systems. The electrical control devices are widely preferred because of the following reasons:

(i) They can be easily controlled.

(ii) They improve the overall control flexibility of fluid power systems.

(iii) They provide quick and accurate control operations.

(iv) They require less maintenance.

(v) They exhibit better reliability and have longer service life.

In addition the complete automation requires the electrical signals (from computer interfaces) to control the machines.

In this chapter, we shall identify and understand the various electrical components used in the control of fluid power. Also we shall explain how these components are used in various ladder diagrams.