FAILURE DETECTING SYSTEM FOR ELECTRICALLY DRIVEN MOTORS OF TOWER CRANES
Aysan Keskin-Ömer Kemal Çatmakaş
Electronic and Communication Engineering Department, Çankaya University
Abstract
The aim of the project is designing a failure detecting system for
electrically driven motors of tower crane. This project is made for
Bayraklar Makine AŞ which is a member of İŞİM cluster.
In the failure detecting system based on rotations of engine parts. To
detect this rotational motion dynamo used as a mechanical sensor,
dynamo is such a device that converts mechanical energy to electrical
energy. A typical dynamo structure is given in figure 3.
Results and Conclusions
V1
LOJIK 0
+5V
R1
1
2
10k
1
0
2
2
R3
3.3k
3
1
Switch
2
1
5
0
ADC0804
C1
1
19
R2
2
150pF
1
D6
2
10k
D7
D5
4
D4
D3
Analog Giris
D2
6
D1
7
Introduction
D0
8
Tower crane is a constructional lifting machine. Tower cranes has three
main engines as marked in figure 1.
1. Lifting Engine
2. Transport Engine
3. Slewing Engine
10
0
Fig. 6. Whole engine control circuit.
Fig. 3. A typical dynamo structure. Dynamo generates voltage according to
rotation of magnet, this generated voltage can be positive or negative
according to direction of rotation, and speed of the rotation determines the
amplitude of generated voltage.
The voltage is generated by dynamo is going to be used in analog to
digital converter. Analog to digital converter quantizes positive analog
data, dynamo generates both positive and negative voltage, to polarize
the negative voltage polarization rectifier circuit is used. Polarization
rectifier circuit is shown in figure 4.
Three of eight quantized data is used for inputs of microprocessor,
microprocessor start to process data by the time the engines start to
motion, according to these inputs microprocessor decides the
engine has failure if the output of ADC804 is 00000000, then
microprocessor send data to main control circuit as an engine has
failure. If the output of ADC804 is XXX111XX microprocessor
decides there is no failure. Whole implemented circuit is shown in
figure 7.
The designed system is start to working with the motion of engine.
Dynamo detects the motion of engine, then dynamo start to generate
voltage, according to rotation direction of the dynamo the generated
voltage can be positive or negative. Negative voltage cannot be quantized
by ADC804 so this negative voltage is polarized by a polarization
rectifier. Output of the polarization rectifier is ready to use as input of
analog to digital converter. Analog to digital converter has one input and
has eight outputs, sixth pin of converter is the input of the converter,
between eleventh and eighteenth pins are output. The dynamo generates
voltage around 0.3 volts. Analog to digital converter quantizes 0.3 volts
as 00011100. This mean the output of converter D2, D3, D4 is one the
others are zero. So as inputs of microprocessor D2, D3 and D4 are used.
The relative engine get command to work, when the engine run
microprocessor start to work. If none of inputs of microprocessor is one
microprocessor decides there is a failure is occurred. Main control circuit
is placed to operator cabin so whenever any failure is detected the
operator is informed.
This system detects the failures of electrically driven motors of tower
crane. The system can be applied to more than one tower crane and all
main control circuits can create a network. The owning company can see
the operation of all tower cranes on a network This work can be extended
to cover other types of cranes
Literature cited
Orhan
Altınbaşak,
Mikroişlemciler,
Atlas
Yayınevi,
İstanbul(2007)
Robert L. Boylestadt, Louis Nashelsky, Electronic Devices
and Circuit Theory, Prentice Hall, New Jerssey (2002)]
http://tr.wikipedia.org/wiki/Dinamo
http://www.microchip.com/
http://www.altaskitap.com/
Figure 1. The photo of a typical tower crane, where the three main engines
are also marked.,
In engines failures can be both mechanical and electrical.
The designed system can diagnoses the both of failure types.
Materials and methods
The designed system is microprocessor based system. This system has
three engine circuits and one main control circuit, and seven segment
display all engine circuits are connected main control circuit. The block
diagram of the system is shown in figure 2.
FIRST
ENGINE
CIRCUIT
SECOND
ENGINE
CIRCUIT
Fig. 4. Polarization rectifier circuit. Converts negative input to positive output.
After the polarization output of polarization rectifier is ready to use
analog to digital conversion, as analog to digital converter ADC804 is
used. Analog to digital converter has one input and eight outputs. Analog
to digital converter quantizes data according to amplitude of the input.
ADC804 quantizes inputs between 0Volt and 5Volts, the output values
are in binary data form 0 Volt quantized as 00000000 and 5 Volt
quantized as 11111111. In figure 5 detailed measurements of ADC804 is
given and in figure 6 implementation of ADC804 circuit is given.
Fig. 7. Whole engine control circuit.
Main control circuit is connected to three of motor control circuits,
if any failure occurs in an engine main control circuit gives the
output on seven segments’ display, related to engine number. The
circuit diagram of main control circuit is given in figure 8.
Acknowledgments
We thank to Assistant Prof Dr. Serap Altay ARPALI for advising
us and, Assoc. Prof. Dr. Halil T. EYYUBOĞLU for brief
explanations , and Instructor Dr. Çağlar ARPALI for helpful
discussions and Murat Dere for laboratory assistance.
THIRD
ENGINE
CIRCUIT
MAIN
CONTROL
CIRCUIT
Photo
SEVEN
SEGMENT
DISPLAY
Figure 2. Block diagram of the system
Figure 5. Input output graphic of ADC804
Fig. 8. Main control circuit and seven segment displays