fundamentals of electrohydraulics (collection of transparencies)

Collection of

Transparencies

TP 601

Festo Didactic

095051 en

Fundamentals ofElectrohydraulics

Order no.: 095051

Designation: E.-HYDR-FOLIEN.

Description: D:OT-TP601-GB

Edition: 07/2001

Author: Dieter Scholz

Graphics: Doris Schwarzenberger

Layout: 18.07.2001, Beatrice Huber

© Festo Didactic GmbH & Co., D-73770 Denkendorf, 2001

Internet: www.festo.com/didactic

e-mail: [email protected]

The copying, distribution and utilization of this document as well as the

communication of its contents to others without expressed authorization is

prohibited. Offenders will be held liable for the payment of damages. All rights

reserved, in particular the right to carry out patent, utility model or ornamental

design registration.

Foreword

© Festo Didactic GmbH & Co. • Electrohydraulics

This set of overhead transparencies has been designed for use with the basic level

of the technology package TP600 “Electrohydraulics”. The set of overhead

transparencies and the technology package form part of the Learning System for

Automation from Festo Didactic GmbH & Co.

The 30 transparencies in this set have been optimised from the didactic and

methodological points of view. Each transparency is accompanied by a short text

which provides the trainer with a quick overview of the training contents of the

transparency concerned.

� Basic principles of electrohydraulics

� Function and use of electrohydraulic components

� Basic principles of electrical engineering

� Production and interpretation of standard hydraulic and electrical circuit

diagrams

The text sheet includes a complete illustration of the transparency, in certain cases

with additional explanations and legends which the trainer can enter on the

transparency in the course of a training session.

The advantages of this concept are:

� The trainer can add to the transparencies step by step in the course of a training

session.

� The trainer is thus able to create a lively and interesting atmosphere.

� The provision of accompanying text means less preparation work for the trainer.

The enclosed CD-ROM contains the entire overhead transparencies and

accompanying text of this edition in an electronically presentable form in the files

„Electrohydraulics _transparencies.pdf“ and „Electrohydraulics _text.pdf“. In

addition to the screen presentation, which can be made in any order, the contents

can be printed out and text and graphics can be used for your own training

preparations, insofar as the functionality of the required Adobe®

Acrobat®

Reader

permits this. This freely distributable software is available on the CD-ROM in the

currently valid English version for Windows 95/98/NT for installation in the directory

„Acrobat_Reader“. Please start the file „rs405eng.exe“ and follow the subsequent

dialogue.

Training contents

New!

Electronic presentation

Contents


Electrohydraulic press _______________________________________ Transparency 1

Schematic layout of an electrohydraulic installation ______________ Transparency 2

Electrical power supply unit __________________________________ Transparency 3

Electrical circuit ____________________________________________ Transparency 4

Measuring circuits __________________________________________ Transparency 5

Ohm’s law _________________________________________________ Transparency 6

Rectifiers __________________________________________________ Transparency 7

Analogue, digital and binary __________________________________ Transparency 8

Momentary and sustained contact switches _____________________ Transparency 9

N/O, N/C and changeover contacts ___________________________ Transparency 10

Limit switches _____________________________________________ Transparency 11

Proximity switches _________________________________________ Transparency 12

Solenoid (electromagnet) ___________________________________ Transparency 13

Electrohydraulic converters (solenoid valves)___________________ Transparency 14

Dry solenoids – wet solenoids________________________________ Transparency 15

Solenoid valve connections__________________________________ Transparency 16

Relays and contactors ______________________________________ Transparency 17

Direct activation – indirect activation __________________________ Transparency 18

Signal inversion ___________________________________________ Transparency 19

Latching__________________________________________________ Transparency 20

Circuit diagram ____________________________________________ Transparency 21

Hydraulic power pack_______________________________________ Transparency 22

Hydraulic circuit ___________________________________________ Transparency 23

Electrical power – hydraulic power ____________________________ Transparency 24

Power losses______________________________________________ Transparency 25

Pressure switches__________________________________________ Transparency 26

4/3-way solenoid valve _____________________________________ Transparency 27

4/3-way solenoid valve, piloted ______________________________ Transparency 28

Electrical safety____________________________________________ Transparency 29

Hydraulic safety ___________________________________________ Transparency 30

1


Electrohydraulic press

� Motor with hydraulic pump

� Control panel

� Valve manifold

� Cylinder

The hydraulic press is controlled via the electrical control panel.

Electrical signals are used to activate the valves in the hydraulic installation.

The electrohydraulic press is used to form rectangular troughs.

Control pane

Motor withhydraulic pump

Valve manifold

Actuator(cylinder)

Function units

© Festo Didactic GmbH & Co. TP 601, 01Transparency

Electrohydraulic press

2


Schematic layout of an electrohydraulic installation

Division of installation into signal control section and hydraulic power section.

Input and processing of electrical signals.

Solenoid valves form the interface between the electrical signal control section and

the hydraulic power section.

Controls the flow of hydraulic fluid by means of solenoid valves. Actuators convert

hydraulic energy into motions.

��

Signal control section

Signalinput

Hydrauliccylinder

Solenoidvalve

Hydraulicpowersupply(conversion)

Powersupply

Signalprocessing

Power section

� �

��


Hydraulic power section

��


Schematic layout of an electrohydraulic installation


Power section

� �

��

3


Electrical power supply unit

Connection to mains supply.

Supplies signal control section with specified or maximum voltage and current

values.

� Voltage transformation

� Rectification

� Smoothing

� Stabilisation

� Fuse protection

In mobile hydraulic systems, rechargeable battery systems or generators are used

as a power supply for the signal control section.

230VAC

24VDC

TR

50 °C

G C T T

Transformer Rectifier Smoothing Stabilisation Fuse

Functions in

power supply unit


Electrical power supply unit

230VAC

24VDC

TR G C T T

4


Electrical circuit

A circuit consists of at least a power source, a load device and connecting lines.

Electrical current will flow only in a closed circuit.

Electrical current flows from the positive terminal of the power supply to the

negative terminal.

Closed circuit without power supply.

Introduction of a power supply to complete the circuit.

A B

+

Technical direction

of current flow

Figure A

Figure B


Electrical circuit

A B

5


Measuring circuits

The voltage drop across a load device is measured in parallel with the device.

Electrical current is measured in series.

++

Voltage measurement Current measurement

Voltage measurement

Current measurement


Measuring circuits

++

--

6


Ohm’s law

Describes the relationship between current (I), voltage (V) and resistance (R).

With ohmic resistances, the current rises in linear proportion to the voltage.

The value pairs for a constant resistance lie on a straight line. The current I is

proportional to the voltage V.

Mathematical formula for Ohm’s law: V = R • I

I = V : R

+

R

A

2.0

1.5

1.0

0.5

0100 20

V

I

30 40V

10 V

0.5 A

0.33 A

Voltage V

20 V

1.0 A

0.66 A

30 V

1.5 A

1.0 A

40 V

2.0 A

1.33 A

A

V

V = R • I

I =RV

Resistance R

Relay

Solenoid coil

Ohm’s law

Graph

fundamentals of electrohydraulics (collection of transparencies)

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