Critical Examination of Failures of Power System Design a

The fault analysis of a power system is carried out to provide proper information for the selection of switchgear, relays setting and system stability operation. The basic circumstances for the occurrence of fault in a power system are due to insulation failure, physical damage or human error. The fault may be in nature of symmetrical or asymmetrical and also it is due to broken conductors in one or more phases. The fault analysis of a power system is carried out to provide proper information for the selection of switchgear, relays setting and system stability operation. Keyword: Fault analysis, power system f symmetrical faults


Introduction:
The generation, transmission and distribution of electrical power are concerned with large interconnected power system. First electrical power generation is take place in power plant, now for the distribution purposes we require high voltage in order to reduce line current thereby transmission loss. So for the transmission level generated voltage is stepped-up by means of transformer.
To maintain continuous power supply is the prime objective of any power system. There are a few abnormal or other natural events which disturb the stability of power system, like wind & ice, physical accident and broken conductor in one or more phases etc. The fault analysis of a power system is carried out to provide proper information for the selection of switchgear, relays setting and system stability operation. The basic @ IJTSRD | Available Online @ www.ijtsrd.com | Volume -2 | Issue -1 | Nov-Dec 2017 The fault analysis of a power system is carried out to provide proper information for the selection of switchgear, relays setting and system stability operation. he basic circumstances for the occurrence of fault in a power system are due to insulation failure, physical damage or human error. The fault may be in nature of symmetrical or asymmetrical and also it is due to broken fault analysis of a power system is carried out to provide proper information for the selection of switchgear, relays setting Fault analysis, power system failure, and The generation, transmission and distribution of electrical power are concerned with large interconnected power system. First electrical power generation is take place in power plant, now for the distribution purposes duce line current thereby transmission loss. So for the transmission level up by means of transformer.
To maintain continuous power supply is the prime objective of any power system. There are a few abnormal vents which disturb the stability of power system, like wind & ice, physical accident and broken conductor in one or more phases etc. The fault analysis of a power system is carried out to provide proper information for the selection of switchgear, relays setting and system stability operation. The basic circumstances for the occurrence of fault in a power system are due to insulation failure, physical damage or human error. The fault may be in nature of symmetrical or asymmetrical and also it is due to bro in one or more phases. A power system failure is not static but changes during operation (switching on or off of generators and transmission lines) and during planning (addition of generators and transmission lines). Faults may be symmetrical or a symmetrical nature. A symmetrical fault is one where one or two phases are involved. fault may be due to short and live conductor, it may be due to broken conductor in one or more phases, but sometimes the occurrence of fault may be the reason involving both the factor means short-circuit as well as broken conductor.
When the insulation of the system fails at one or more points or a conducting object comes into contact with a live point, a short circuit or a fault occurs. akur Polytechnic, Pakur ngineering, circumstances for the occurrence of fault in a power system are due to insulation failure, physical damage or human error. The fault may be in nature of symmetrical or asymmetrical and also it is due to broken conductors in one or more phases. A power system failure is not static but changes during operation (switching on or off of generators and transmission lines) and during planning (addition of generators and transmission lines). Faults l or a symmetrical nature. A symmetrical fault is one where one or two phases are involved. fault may be due to short-circuit between earth and live conductor, it may be due to broken conductor in one or more phases, but sometimes the occurrence of ay be the reason involving both the factor means circuit as well as broken conductor.

CAUSES OF POWER SYSTEM FAILURE
When the insulation of the system fails at one or more points or a conducting object comes into contact with a live point, a short circuit or a fault occurs. Power system failure may be categorized as one of four types; in order of frequency of occurrence, they are:

ES OF POWER SYSTEM FAILURE
 Single line to ground failure  Line to line failure  Double line to ground failure  Balanced three phase failure The first three types constitutes severe unbalanced operating conditions which involves only one or two phases hence referred to as unsymmetrical faults. In the fourth type, a fault involving all the three phases occurs therefore referred to as symmetrical (balanced) fault.

Fault Analysis:
Under normal condition, power system said to be working under balanced condition with all the equipment having a normal load current and bus voltage within a specified limit. The balance condition of a power system may be disrupted due to fault in the system. The fault in a system is nothing but a failure that interfaces with normal flow of current. Short circuit possess a very huge amount of current in the circuit, hence for the protection purpose we need protective equipment to avoid damage of equipment. Short circuit may be classified as:-

EFFECTS OF POWER SYSTEM FAILURE
Failure may lead to fire breakout that consequently results into loss of property, loss of life and destruction of a power system network. Faults also leads to cut of supply in areas beyond the fault point in a transmission and distribution network leading to power blackouts; this interferes with industrial and commercial activities that supports economic growth, stalls learning activities in institutions, work in offices, domestic applications and creates insecurity at night. It necessary upon occurance of fault, the faulty section must be disconnected from the system as soon as possible, that's why because the healthy part of the system not affected.

Literature Review
There are so many literatures available on reliability of power system, stability and causes of fault and symmetrical and a symmetrical fault. Here a few has been taken for reference and further work has been carried out.

Research Methodology
To enable the analysis of failure potential during early design, functional modeling has been introduced in prior work as a basis for system representation for the majority of design stage reliability methods. Functional modeling is a system representation method, developed as a means to enhance the concept generation stage of product design (Pahl and Beitz, 1996). Using this approach, designers identify specific functions that a product must accomplish and connect these functions in a block diagram with the EMS flows that are transformed by the functions. Functional modeling has also been used in reverse engineering methods such as the Force Flow Analysis. This method dissects products into components and the forces acting on and between components and finally into the functions that components embody. Most of the function-based methods in the research community make use of the Functional Basis (Hirtz et al., 2002; Stone and Wood, 2000) in order to provide a standard taxonomy for concept design and avoid the use of designer specific function and flow descriptions. Based on the usefulness of functional modeling for system representation in early design, it has also been used as part of the system representation in many early design reliability methods.
The first method that proposed a function-based approach to failure analysis was the Failure propagation is analyzed using a Function Event Network of all possible causation relationships in the function structure. This type of approach probabilistic analysis by applying a statistical reliability to the failure of each function in the function structure. An extension of this work is the Conceptual Stress and Conceptual Strength Interference Theory (CSCSIT) method (Huang and Jin, 2008), where the conceptual strength of a function is the ability of a function to continue to operate while under normal energy, material and signal (EMS) flows. In this method, conceptual stresses are the EMS flows in the function structure. The application of interference theory is used to define functional faults as when the output flow from a function is out of a specified normal range.

CONCLUSION
Fault analysis or short circuit analysis is carried out to determine the value of voltage and hence current during the event of fault, it helps for the appropriate selection of the circuit breaker. So that we can save the power network with abnormal or unbalance condition with a minimum time.
introduced above, a failure propagation method was Lough (Krus and ailure propagation mapping based on historical data using a functional Failure propagation is analyzed using a Function Event Network of all possible causation relationships in the function structure. This type of approach allows for a probabilistic analysis by applying a statistical reliability to the failure of each function in the function structure. An extension of this work is the Conceptual Stress and Conceptual Strength Interference Theory (CSCSIT) Jin, 2008), where the conceptual strength of a function is the ability of a function to continue to operate while under normal energy, material and signal (EMS) flows. In this method, conceptual stresses are the EMS flows in the function structure. The lication of interference theory is used to define functional faults as when the output flow from a function Fault analysis or short circuit analysis is carried out to current during the event of fault, it helps for the appropriate selection of the circuit breaker. So that we can save the power network with abnormal or unbalance condition with a