Introduction

Tower crane is a constructional lifting machine. Tower cranes has three main engines as marked in figure 1.1.Lifting Engine2.Transport Engine3.Slewing Engine

In engines failures can be both mechanical and electrical. The designed system can diagnoses the both of failure types.

Materials and methodsThe 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.

AcknowledgmentsWe 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.

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.

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.

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.

Results and Conclusions

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

FAILURE DETECTING SYSTEM FOR ELECTRICALLY DRIVEN MOTORS OF TOWER CRANESAysan Keskin-Ömer Kemal Çatmakaş

Electronic and Communication Engineering Department, Çankaya University

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/Dinamohttp://www.microchip.com/http://www.altaskitap.com/

Figure 1. The photo of a typical tower crane, where the three main engines are also marked.,

Figure 2. Block diagram of the system

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.

Photo

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.

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.

Figure 5. Input output graphic of ADC804

Fig. 7. Whole engine control circuit.

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.

FIRST ENGINE CIRCUIT

SECOND ENGINE CIRCUIT

THIRD ENGINE CIRCUIT

MAIN CONTROL CIRCUIT

SEVEN SEGMENT DISPLAY

Fig. 8. Main control circuit and seven segment displays

Fig. 4. Polarization rectifier circuit. Converts negative input to positive output.

21

6

4

7

8 10

LOJIK 0

3

5

19

R 1

1 0 k

21

R 2

1 0 k

21

R 33 . 3 k

2

1

0

0

C 1

1 5 0 p F

1 2

A D C 0 8 0 4

S wit c h

0

1 2

A n a lo g G ir is

D 7

D 6

D 5

D 4

D 3

D 2

D 1

D 0

V 1+5 V

Fig. 6. Whole engine control circuit.