Abstract

Overvoltage and under voltage are quality problems, they happen due to many reasons. The effects of overvoltage and under voltage can be severe and can cause insulation failure in case of overvoltage and overheating and burning of motors coils in case of under voltage.

To solve the problem a tripping mechanism is designed to disconnect the load when subjected to overvoltage, under voltage or imbalance operation in case of three phase equipment. The design is first simulated in a virtual environment using a simulation program, and then a hardware design is made according to the simulated circuit. The system will save costly

electrical and electronic appliances from the adverse effects of very high and very low mains voltages. A project has been proposed on simulating an overvoltage and under-voltage protector, with the hardware This circuit might be embedded between a current programmed/manual stabilizer and the heap. The over/under voltage cut-off with ON-Time delay gives different sorts of security: Over voltage/under voltage assurance, insurance against homeless people and so on.

GENERAL INTRODUCTION:

As the demand of electrical energy increases more generating units, transmission lines are added to the system, which in turn increases its complexity, making the system more prone to faults and disturbances.

Now-a-days, greater demands have been placed on the transmission network, and these demands will continue to rise because of the increasing number of nonutility generators and greater competition among utilities themselves. Increased demands on transmission, absence of long-term planning, and the need to provide open access to generating companies and customers have resulted to less security and reduced quality of supply [1]. Several types of power enhancement devices have been developed over the years to protect equipment from power disturbances, but these devices can also fail or malfunction sometimes. Thus, the need for more security is always wanted.

Increase in the r.m.s. (roof means square) value of the voltage up to a level between 1.1 pu (per unit) to 1.8 pu (per unit) at power frequency for periods ranging from a half cycle to a minute is known as over voltage while a voltage which is below the optimum operational or rated value of a component, circuit or device is called an under voltage [2]. This project has five chapters with chapter one talking about the overview of the project, chapter two talking about literature review, chapter three talking about the component types needed to realise this project, chapter four the implantation and chapter five conclusion and recommendation.

CHAPTER ONE

 OVERVIEW OF PROJECT

1.1.  Overview

The sudden instability in voltage is colossal and noteworthy issue in undertakings and homes, it causes hardships and moreover hurt the electrical circuit. These incidents cause low impact factor in the supply and by much proportion of impact will be misused. What’s more, besides impact the unfaltering nature of other voltage controlling devices. Voltage swells and over voltage conditions are about caused by a sudden reduction in stack.

Right when RMS voltage or current drops in the region of 0.1 and 0.9 pu at the power recurrence for the ranges of 0.5 cycles to 1 minute then it is said to be hang condition.

The swell condition will happen when RMS voltage or current climbs in the region of 1.1 and 1.8 pu at the power repeat for lengths of 0.5 to 1 minute. Or then again more the 1.8pu and underneath circuit with a hurt voltage controller, notwithstanding the way that they can in like manner be caused by a hurt or free impartial affiliation

Along these lines, the issues happened as a result of hang, swell, over and under voltage condition ought to be ousted and it will be recognized and guaranteed by this system. In this paper we execute a circuit which recognizes the voltage underneath 198 volts which is 0.9 of assessed voltage i.e. 220 volts then it is called list or under voltage condition. In this condition our circuit will remain in open condition so there will be no any section of current and lower hand-off of our circuit will remain open.

Right, when the voltage rises above 242 voltages which are 1.1 of our assessed voltage then it is brought swell and over-voltage condition, in this situation the circuit will remain open in light of the fact that in that time upper move in the circuit will remain open. In this way, we can anchor the over-the-top riggings by going the supply through this circuit [3].

1.2. Problem Statement

The effects of overvoltage and voltage to electric equipment in general and motors specifically are serious and can’t be ignored. Overheating and insulation failure might happen when electric equipment is subjected to under or over voltage conditions.

Moreover, the condition maybe hazardous, depending on its duration, it is more serious in the case of domestic appliances like fridges and air conditioners. If a fridge is operated on low voltage, excessive current flows through the motor, which heats up and gets damaged.

The economic loss from premature motor failure is devastating. In most cases, the price of the motor itself is trivial compared to the cost of unscheduled shutdowns of processes. Both high and low voltages can cause premature motor failure, as will voltage imbalance. This project is therefore designed to develop a low voltage and high voltage tripping mechanism to protect a load from any damage.

1.3. Objectives

1. To develop a tripping mechanism to protect the load from over voltage and under voltage in general.
2. To develop a tripping mechanism to protect three phase motors from under voltage, overvoltage, imbalance operation and phase failure.

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