Introduction Definition And Explanation Engineering Essay

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Induction motor system is nowadays widely used especially in industry. It is exist either in three phase supply or single phase supply. Induction motor is a type of AC power which in other words the power is supplied to the rotor through the electromagnetic induction. This is the different to the DC motor where the power supplied to the rotor through the commutator or slip rings.

Three phase AC induction motor are the prime movers for the vast majority of machines for industrial and mining applications. These motors can operated directly from the mains supply or event through the adjustable frequency drives such as variable speed drive (VSD).[1]

From the industrial sector it also extends the application in commercial buildings and domestic environment. It is not surprising to find that the AC induction motor is so popular and well known. This is because if comparison is made between the AC induction motors and DC motor, the AC induction motor has higher reliability than DC motor. Besides that, AC induction motor is more simples in construction and operation compared to DC motor. Moreover, in aspect of costing, AC induction motor is cheaper than DC motor.

The application of AC induction motor covers almost every stage of manufacturing and processing even extended to commercial buildings and domestic environments. The popular application that utilised the AC induction motor is water pump system. According to [2], 65% of the motor electricity consumption in the European Union industry is caused by pumping systems. In addition, based on the survey made by the Energy Commission of Malaysia stated that 70% of the electricity used in industries is by the electric motor. [3]

The functions of the pump are mainly to transfer the liquid from one places to another place for example water from an underground into a water storage tank. Besides that, pumps also circulate liquid around the system such as circulates the cooling water or lubricants through machines and equipment.

In the markets, there are many types of pump are exist which can fit for many application. Through out of this study, centrifugal pump is been selected as the induction motor. The centrifugal pump is the most used pump type in the world. The principle is simple, well-described and thoroughly tested, and the pump is robust, effective and relatively inexpensive to produce. The centrifugal pump is machine which specifically imparts energy to a fluid. This energy cause the movement of liquid to higher level or lower lever or even both.[4]

1.2. Pump History

The brief history of the pump is the centrifugal pump was developed in Europe in the late 1600's and was seen in the United Stated in the early 1800's. It is wide spread use are only occurred in the last seventy-five years. The centrifugal pump is highly popular due to the development of high speed electric motors, steam turbines and internal combustion engines.

The centrifugal pump has become the most preferable pump for most industry application since 1940's. Research and development has resulted in both improved performance and new materials of construction that have greatly expanded it's field of application [4].

Nowadays, the centrifugal pumps have been designed to meet conditions beyond what was thought past sixty years ago. Pumps that have the capability to deliver more than 1000000 gallons per minute at head of over 300 feet can be found in the nuclear industry.

1.3 Types of pump

Nowadays, pump come in a variety of sizes for a wide range of applications. They can be classified according to their basic operating principle as dynamic or displacement pumps. Dynamic pumps can be sub-classified as centrifugal and special effect pumps. Displacement pumps can be sub-classified as rotary or reciprocating pumps.

In principle, any liquid can be handled by any of the pump designs. Where different pump designs could be used, the centrifugal pump is generally the most economical followed by rotary and reciprocating pumps. Although, positive displacement pumps are generally more efficient than centrifugal pumps, the benefit of higher efficiency tends to be offset by increased maintenance costs.

Since, worldwide, centrifugal pumps account for the majority of electricity used by pumps, the focus of this project is on centrifugal pump.

1.4 How does pump operate

The centrifugal pump consists of two main parts which are the impeller and the diffuser. Impeller, the only moving part, is attached to a shaft and driven by a motor. Impellers are generally made of bronze, polycarbonate, cast iron, stainless steel as well as other materials. The diffuser houses the impeller and captures and directs the water off the impeller. Water enters the centre of the impeller and moves out from the impeller with the help of centrifugal force.

Figure 1.4.1 Centrifugal pump

As water leaves the eye of the impeller a low-pressure area is created, then causing more water to flow into the eye. Atmospheric pressure and centrifugal force cause this to happen. Velocity is developed as the water flows through the impeller spinning at high speed. The water velocity is collected by the diffuser and converted to pressure by specially designed passageways that direct the flow to the discharge of the pump, or to the next impeller should the pump have a multi-stage configuration. The pressure (head) that a pump will develop is in direct relationship to the impeller diameter, the number of impellers, the size of impeller eye, and shaft speed. Capacity is determined by the exit width of the impeller. The head and capacity are the main factors, which affect the horsepower size of the motor to be used. The more the quantity of water to be pumped, the more energy is required.

1.4 Variable speed drive

Variable-speed drive (VSD) describes equipment used to control the speed of machinery. Many industrial processes such as assembly lines must operate at different speeds for different products. Where process conditions demand adjustment of flow from a pump or fan, varying the speed of the drive may save energy compared with other techniques for flow control.

Where speeds may be selected from several different pre-set ranges, usually the drive is said to be adjustable speed. If the output speed can be changed without steps over a range, the drive is usually referred to as variable speed.

An adjustable speed drive can often provide smoother operation compared to an alternative fixed speed mode of operation. For example, in a sewage lift station sewage usually flows through sewer pipes under the force of gravity to a wet well location. From there it is pumped up to a treatment process. When fixed speed pumps are used, the pumps are set to start when the level of the liquid in the wet well reaches some high point and stop when the level has been reduced to a low point. Cycling the pumps on and off results in frequent high surges of electric current to start the motors resulting in electromagnetic and thermal stresses in the motors and power control equipment, the pumps and pipes are subjected to mechanical and hydraulic stresses, and the sewage treatment process is forced to accommodate surges in the flow of sewage through the process. When adjustable speed drives are used, the pumps operate continuously at a speed that increases as the wet well level increases. This matches the outflow to the average inflow and provides a much smoother operation of the process

VSDs allow pump speed adjustments over a continuous range, avoiding the need to jump from speed to speed as with multiple-speed pumps. VSDs control pump speeds using several different types of mechanical and electrical systems. Mechanical VSDs include hydraulic clutches, fluid couplings, and adjustable belts and pulleys. Electrical VSDs include eddy current clutches, wound rotor motor controllers, and variable frequency drives (VFDs).

However, pump speed adjustment is not appropriate for all systems. In applications with high static head, slowing a pump risks inducing vibrations and creating performance problems that are similar to those found when a pump operates against its shutoff head. For systems in which the static head represents a large portion of the total head, caution should be used in deciding whether to use VFDs. Operators should review the performance of VFDs in similar applications and consult VFD manufacturers to avoid the damage that can result when a pump operates too slowly against high static head.

1.6 Objectives of Study

In determining the purpose and the direction of this analysis, there are several objectives which need to be accomplished in developing this project, The project aims to achieves the following objectives:

To analyze ramping effect on induction motor system under various loading conditions.

To analyze the impact on the induction motor for different type of acceleration and deceleration (ramping) setting.

To determine a simple algorithm to assist engineers to determine an appropriate ramping setting for a motor system.

1.7 Research Methodology

This study was divided into 4 main stages as follows:

i. Literature review;

ii. Experimental work;

iii. Data analysis and interpretation; and

iv. Report writing

Details of each stage are as shown in Figure 1.7

Literature Review

Literature review was based on resources from articles, journals, books and previous works. The review includes:

i) History and evolution of centrifugal pump

ii) operation in pump

iii) Components in centrifugal pump

iv)Types of pump in market

v) System design between pump and variable speed drive

Experimental Work

i) Experimental set up

ii) Circuit description and connection

iii) Physical layout

iv) Testing, Measurement and Troubleshooting

Data Analysis and Interpretation

The collected raw experimental data was further calculated and analyzed to assess the suitability of this technology as an alternative treatment method.

Report Writing

The experiment results, evaluation of the experiment and recommendations are presented as a report.

Figure 1.7: Overview of the Research Methodology

1.8 Organization of Thesis

This thesis is divided into 5 chapters, covering topics on introduction, literature review, methodology, experiment procedure, testing, measurement and troubleshooting, as well as conclusions and recommendation for further study.

The justification for this work, background of study, scope and objective of the study and research methodology are included in Chapter 1.

Chapter 2 consists of literature review focusing on induction motor which is centrifugal pump, operation of centrifugal pump, types of pump , variable speed drive and system design of the whole project.

Chapter 3 includes methods that have been conducted during this study. Theoretical studies cover the first part of this chapter and experimental procedure includes the project overview and hardware implementation on each procedure.

Chapter 4 is the testing, measurement and troubleshooting of the project is done in chapter 5. Results arising from the project were analyzed and presented in this chapter. Data such as power efficiency, solar power input and power loss is taking into account in this project.

The last chapter concludes the results obtained from the analysis and suggest recommendations for future work.