Bachelor of Technology in Electrical Engineering - ethesis

This is to certify that the project titled, "DIAGNOSTIC DIAGNOSIS, DESIGN AND IMPLEMENTATION OF CONTROL CIRCUIT FOR INSTRON FATIGUE TESTING MACHINE" submitted by Tuljappa M Ladwa is an authentic work done by him under our full supervision and guidance of requests. for the award of Bachelor of Technology Degree in Electrical Engineering at National Institute of Technology, Rourkela. In an attempt to start the car, it was necessary to know about the car and there was no material available through which the author could know the operation of the sub-components of the car. Reverse Engineering came to the rescue and the foundation of the car literature was made.

Car fault diagnosis is done to fix many faults in the car. At some point the author realized that it would be difficult to continue fixing the car with the given data extracted from the car. I cannot forget the contribution of this project mentor Prof P K Ray and his project student Sanjay Chauhan.

I am grateful to Prof A.K.Panda for allowing me to use the resources of the Power Electronics Laboratory.

Motivation for the present work
Objectives
Approach
Is Reverse Engineering Legal?

Disassemble the machine by attaching the wires and drawing all the electrical circuits on paper. To make the connection diagram of the machine with respect to various motors, power circuit and other components. I visited NIT Jamshedpur and found that their machine was also not working and the control and protection circuit was also different from ours, so I came back with some pictures of various components of the machine. (September 2009).

In a meeting with the guides, it was decided that it will be difficult for us to repair the machine without the full knowledge of the controller and at some point it was also decided to proceed with the design and implementation of a new controller circuit and protection circuit , but that would take years of thorough research. Supervisors suggested making the machine usable for tensile and compressive testing or to work only moderately, even if fatigue tests are compromised for some time (March, 2010). The DC power supply to test the motor was made and the DC motor was tested, which was the way to start the machine.

The engine was started, allowing daylight adjustment of the machine's upper load string (March, 2010).

Why use Reverse Engineering? [3]

Organisation of the Thesis

In this chapter, the reader will know about the working principle of the machine and its features. In this chapter, the reader will know about the reverse engineering of the machine and errors that were discovered and how the. After going through chapter three, the reader will feel the necessity and importance of the design.

The design and implementation of the control circuit is discussed in detail and the hardware specifications for manufacturing the same. The future work emphasizes the approaches to be taken to restore the machine as a fatigue testing machine or to redesign the whole machine to make it a real product to be patented.

Introduction [1]

The design of the power amplifier is new and is the subject of a patent application. The average load is automatically held on the specimen by four Achme screws at the corners of the spring support structure. The magnet is actuated by high current pulses generated at the natural frequency of the spring/mass assembly in order to maintain a resonant system.

The output of the load cell is approximately proportional to the load applied to the specimen. The load cell amplifier amplifies the load signal in the range of 0 to 10 volts, where 10 volts is the output for the maximum capacity of the load cell. The output of the load cell amplifier is applied to three stages of the controller circuit: a sine-to-square wave converter, a peak load detector, A2, and an average level detector, A3.

A signal is generated in the dynamic compensation module, factored for G as measured by an accelerometer in the load cell and applied to the dynamic load signal to give a true representation of the average maximum load.

SPECIFICATION [1]

POWER FLOW DIAGRAM

A fixed voltage of 195 V is supplied to the DC motor field and the armature voltage is supplied to the DC motor through relay control. The Resistance Potentiometer is used by the user to vary the armature voltage so that the motor speed can be controlled. The circuits are doing the mentioned operation through DC motor relay control and electromagnet control through magnetic controller.

It controls the air gap in the electromagnet through a single phase servo motor as shown in figure [3.1]. The sub-components of the machine and their possible fault diagnosis as taken up for detailed discussion as follows. It is the conversion of AC supply to DC supply which will be supplied to armature and field coils of the DC traction motor.

The field is directly connected to the converter which supplies 195V DC and the armature is connected through relay circuit and the voltage can be varied using Resistance Pot provided in the machine. Examining the voltage of various test points in the CRO, it was found that all the test points except the test point in the pulse transformer responded to signs of health of the circuit. Figure [3.7] is the circuit diagram of the relay circuit and Figure [3.8] shows the circuit diagram of the relay logic board.

The motor is connected to gear mechanism whose rating is as shown in the table [3.4]. The axle of the car together with the gear system was corroded, due to which there was mechanical jamming. The motor gear system was placed back into the machine and the tires were connected to the system.

The test was carried out using a rheostat in series with the armature of the motor which it passed successfully. This comes out of the magnet controller and is used to adjust the air gap in the magnet.

Electro Magnet

Figure [3.13] shows the total circuit diagram of the control circuit where the cards will be connected. The switches select the counting methods for the counter circuit, either the time in seconds or the number of oscillation cycles of the resonant system. Balance Controls This control is used to balance the load cell output for the weight of the sample, clamps and adapters so that the load output after balancing is representative of the load applied to the sample.

Caliper Controls This control adjusts the gain of the load cell amplifier board so that 10 volts is output. The system can be reset by pressing the small button on the load cell protection module. It is adjusted for maximum response (minimum time delay) in proportion to the smooth operation of the system light.

Figure [3.19] shows the complete circuit diagram of the protection circuit of the circuit where the logic cards will be installed. A three-position switch above the preset level potentiometer is set for the direction from which the preset limit approaches the control parameter, the center position of the switch being the "off" position for that particular half-module. If it is in the "opposite position", the test will not stop, but the LED will light up, indicating that the boundary condition has been reached; in both cases the counter, if in use, is stopped.

The more compressive the load and the more negative the signal representing the load, up to a maximum of -10 volts. The D.V.M console displays the level in 10 mV steps and a decimal point is inserted before the first digit. This causes 10 volts to appear as 100.0, i.e. The DVM displays the load signal as a percentage of the load cell capacity.

Therefore, before setting the limit, the desired level must be converted into a percentage of the capacity of the measuring cell. If the preset limit is more negative than the corresponding control parameter, the direction of the toggle switch must be set down. During the test, the D.V.M console may display the control parameter level, which is limited by selecting the appropriate switch under the D.V.M.

Gasoline and thinner were used to clean the circuit board and remove rust from the circuit board.

Figure 3.11 Load cell, courtesy: Instron

AC series motor [8]

CONTROL CIRCUIT
MOTOR CONTROL FOR UPPER LOAD STRING
PROJECT OUTCOMES AND EXPECTATIONS
FUTURE WORK
APPROACHES FOR FUTURE WORK

The objective is to provide flexibility to the load cell for both tension and compression operation, when the load cell reaches the lower or upper limit of the load, then the relay [6] should cause the motor driving the load cell to trip. The logic here is that a 12 V DC supply should only be given to the coil of the relay when the limit switch is not actuated and the push button [5] is pressed for the desired operation. The tensile or compressive load is determined by the polarity of the supply given to the armature.

The motor is single-phase AC series which is connected to the upper load string of the machine by mechanical arrangement. The top load string is only used to adjust the job according to the size of the job. The project started with the intention of restoring the machine as a fatigue testing machine, but ended up reverse engineering the machine and changing its functionality, making it work as compression and tensile testing.

In the future, the machine can be repaired back if some error occurs because the documentation of the machine was done with the same in mind. The functionalities of the chips used in the circuit diagrams obtained in the reverse engineering process must be understood. The block diagram of the entire power flow diagram must be constructed by neglecting the parasitic resistances and capacitances.

From the current stage of the project, it can be used for average loading, so now the load cell calibration must be done to standardize the voltage according to the load applied. A proper modeling of the machine is necessary to fully understand the technical details of the machine. The AC to DC converter can be replaced with the converter with software controlled firing of the gate pulse for the same power rating.

The speed control should be software based logic in order to achieve a good control of the displacement of the load cell. Car protection should be given the highest priority even if it requires reducing the frequency limit.