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
© Festo Didactic GmbH & Co. • Electrohydraulics
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
© Festo Didactic GmbH & Co. • Electrohydraulics
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
© Festo Didactic GmbH & Co. • Electrohydraulics
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
� �
��
Signal control section
Hydraulic power section
��
© Festo Didactic GmbH & Co. TP 601, 02Transparency
Schematic layout of an electrohydraulic installation
Signal control section
Power section
� �
��
3
© Festo Didactic GmbH & Co. • Electrohydraulics
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
© Festo Didactic GmbH & Co. TP 601, 03Transparency
Electrical power supply unit
230VAC
24VDC
TR G C T T
4
© Festo Didactic GmbH & Co. • Electrohydraulics
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
© Festo Didactic GmbH & Co. TP 601, 04Transparency
Electrical circuit
A B
5
© Festo Didactic GmbH & Co. • Electrohydraulics
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
© Festo Didactic GmbH & Co. TP 601, 05Transparency
Measuring circuits
++
--
6
© Festo Didactic GmbH & Co. • Electrohydraulics
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