Basic Concept and Purpose of Fault Calculation ,Types of Fault, Causes of Fault, Sources of Fault and Effect Of Faults

The purpose of fault calculation is to calculate fault current.Fault calculation is essential to find the rating of the protective devices such as: circuit breaker,isolators etc.

Summary

The purpose of fault calculation is to calculate fault current.Fault calculation is essential to find the rating of the protective devices such as: circuit breaker,isolators etc.

Things to Remember

Approximately 75% of all faults in power systems are transient in nature.
Knowing the magnitude of the fault current is important when selecting protection equipment.

MCQs

No MCQs found.

Subjective Questions

Q1:

Write short notes about drugs used in a cough.

Type: Short Difficulty: Easy

Show/Hide Answer

Answer: <h3>Drugs used in a cough</h3>
<ul>
<li>
<h4>Pharyngeal demulcents</h4>
</li>
</ul>
<ol>
<li>Menthol</li>
</ol>
An organic compound made synthetically or obtained from corn mints, peppermint or other mints oil.it has local anesthetic and counter-irritant quantities, has soothing and cooling action.
 
Mechanism of action
It has local anesthetic and counter-irritant quantities have soothing and cooling action.
 
Indication
<ul>
<li>For short-term relief of a minor sore throat and mouth irritation</li>
</ul>
 
Adverse effect
<ul>
<li>Ingestion of pure menthol can be poisonous.</li>
</ul>
<h3>Antitussive agents</h3>
These are the groups that act on the central nervous system to raise the threshold of the cough center or acts peripherally at the respiratory tract to reduce the tissue impulse.
<h4>Codeine</h4>
 
Mechanism of action
It suppresses the cough center in the brain for 6 hours. It also exerts a drying effect in the respiratory tract mucosa.
 
Indication
<ul>
<li>Nonproductive cough</li>
</ul>
 
 
Doses
<ul>
<li>Adult- 10-30mg 3-4 times a day</li>
<li>Child- 2-6 yrs 2.5-5mg 3-4 times a day</li>
</ul>
6-12 yrs 5-10mg 3-4 times a day
 
Contraindication
<ul>
<li>Bronchial asthma</li>
<li>Respiratory depression</li>
<li>Hypersensitivity</li>
<li>Pregnancy</li>
</ul>
 
Adverse effects
<ul>
<li>Nausea vomiting,constipation</li>
<li>Dry mouth</li>
<li>Sweating</li>
<li>Hypotension</li>
<li>Bradycardia</li>
<li>Restlessness</li>
<li>Mood swing</li>
</ul>
 
Nursing consideration
 
<ul>
<li>Do not administer if respiration rate below 12 breath per min,so monitor respiration, pulse rate, and pressure in every 4 hourly.</li>
<li>Inform the patient that it can cause drowsiness mood swing, restlessness.</li>
<li>Advise patient to take adequate amount of fluid/liquid diet.</li>
</ul>
 
 
<h4>Pholcodine</h4>
 
Mechanism of action
It suppresses the cough center in the brain for long hours. It also exerts a drying effect in the respiratory tract mucosa and long action.
 
Indication
<ul>
<li>Nonproductive cough</li>
</ul>
 
Doses
<ul>
<li>10-15mg 12 hrs</li>
</ul>
 
Contraindication
<ul>
<li>Bronchial asthma</li>
<li>Respiratory depression</li>
<li>Hypersensitivity</li>
<li>Pregnancy</li>
</ul>
 
Adverse effects
<ul>
<li>Nausea vomiting, constipation</li>
<li>Dry mouth</li>
<li>Sweating</li>
<li>Hypotension</li>
<li>Bradycardia</li>
<li>Restlessness</li>
<li>Mood swing</li>
</ul>
 
Nursing consideration
 
<ul>
<li>Do not administer if respiration rate below 12 breaths per min, so monitor respiration, pulse rate, and pressure in every 4 hourly.</li>
<li>Inform the patient that it can cause drowsiness mood swing, restlessness.</li>
<li>Advise patient to take adequate amount of fluid/liquid diet.</li>
</ul>
 
<h4>Ethylmorphine</h4>
 
Mechanism of action
It suppresses the cough center in the brain for 6 hours. It also exerts a drying effect in the respiratory tract mucosa.
 
Indication
<ul>
<li>Nonproductive cough</li>
</ul>
 
 
Doses
<ul>
<li>10-15mg TDS/QID</li>
</ul>
 
 
Contraindication
<ul>
<li>Bronchial asthma</li>
<li>Respiratory depression</li>
<li>Hypersensitivity</li>
<li>Pregnancy</li>
</ul>
 
Adverse effects
<ul>
<li>Nausea vomiting,constipation</li>
<li>Dry mouth</li>
<li>Sweating</li>
<li>Hypotension</li>
<li>Bradycardia</li>
<li>Restlessness</li>
<li>Mood swing</li>
</ul>
 
Nursing consideration
<ul>
<li>Do not administer if respiration rate below 12 breaths per min,so monitor respiration, pulse rate, and pressure in every 4 hourly.</li>
<li>Inform the patient that it can cause drowsiness mood swing, restlessness.</li>
<li>Advise patient to take adequate amount of fluid/liquid diet.</li>
</ul>
 
<ul>
<li>Do not administer if respiration rate below 12 breaths per mins, so monitor respiration, pulse rate, and pressure in every 4 hourly.</li>
<li>Inform the patient that it can cause drowsiness mood swing, restlessness.</li>
<li>Advise patient to take adequate amount of fluid/liquid diet.</li>
</ul>
 
<h4>Dextromethorphan</h4>
 
Mechanism of action
It is a synthetic compound which has selective anti- tussive action by raising the threshold of the cough center and is also an analgesic. It is effective as codeine but has no constipating and addicting action.
 
Indication
<ul>
<li>Cough of nonproductive origin</li>
</ul>
 
Contraindication
<ul>
<li>Bronchial asthma</li>
<li>Hypersensitivity</li>
<li>Pregnancy</li>
<li>Respiratory depression</li>
</ul>
 
Adverse effect
<ul>
<li>Nausea</li>
<li>Dizziness</li>
<li>Ataxia</li>
</ul>
 
Nursing consideration
<ul>
<li>As it causes dizziness and drowsiness advise the patient not to drive or does hazardous work.</li>
<li>Do not take/consume alcohol.</li>
</ul>
 
 
 
<h4>Noscapine</h4>
 
Mechanism of action
It belongs to non –opoid group. It depresses a cough but has no narcotic effects or dependence inducing properties in antitussive preparations.
 
Indication
<ul>
<li>Nonproductive cough</li>
</ul>
 
Doses
<ul>
<li>Adult- 15-30mg</li>
<li>Child(2-6 yrs)-7.5mg and 6-12 yrs – 15mg</li>
</ul>
 
Contraindication
<ul>
<li>Bronchial asthma</li>
</ul>
 
Adverse effect
<ul>
<li>A headache and nausea</li>
</ul>
 
Nursing considerations
<ul>
<li>Do not administer if respiration rate is below 12 breaths per mins, so monitor respiration, pulse rate, and pressure in every 4 hourly.</li>
<li>Inform the patient that it can cause drowsiness mood swing, restlessness.</li>
<li>Advise patient to take adequate amount of fluid/liquid diet.</li>
</ul>
 
<h4>Dextromethorphan</h4>
 
Mechanism of action
It is a synthetic compound it has selective antitussive action by raising the threshold of the cough center and is also analgesic. It is effective as codeine but it has no constipating and addicting action.
 
Indication
<ul>
<li>Cough of nonproductive origin</li>
</ul>
 
Doses
<ul>
<li>Adult- 10-20 mg</li>
<li>Child(2-6yrs)- 2.5-5 mg</li>
<li>Child(6-12yrs)- 5-10mg</li>
</ul>
 
Contraindication
<ul>
<li>Bronchial asthma</li>
<li>Hypersensitivity</li>
<li>Pregnancy</li>
<li>Increased intracranial pressure</li>
<li>Respiratory depression</li>
</ul>
 
Adverse effect
<ul>
<li>Nausea</li>
<li>Dizziness</li>
<li>Drowsiness</li>
<li>Ataxia</li>
</ul>
 
Nursing consideration
<ul>
<li>As it causes drowsiness and dizziness the patient should be informed not to drive or do hazardous work.</li>
<li>Encourage the patient not to take alcohol and other harmful and toxic substances.</li>
</ul>
 
References
<ul>
<li>Tamarakar Abhishek,Manandhar Mukta, Essential textbook of Basic science Applied to Nursing,1st edition 2015,Samiksha publication.Pvt/Ltd, Bagabazar Kathmandu</li>
<li>Thapa Kumar Raj, thapa Sharana Hari, A companion pocket book of pharmacy and pharmacology, 1st edition 2007, 3rd revised 2010,September,taleju Prakashan,chittadhar marg,bhotahity,Kathmandu</li>
<li>Tuitui Roshani, Dr. Suwal S.N,Human Anatomy and Physiology,6th edition 2011 A.D,Vidhyarthi Prakashan, Kamalpokhari,Kathmandu</li>
</ul>

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Basic Concept and Purpose of Fault Calculation ,Types of Fault, Causes of Fault, Sources of Fault and Effect Of Faults

Introduction:

The fault is any abnormality in the power system which causes the flow of currents in the un-intended path or the current is diverted from the intended path.For example, a short circuit is a fault in which current bypasses the normal load. An open-circuit fault occurs if a circuit is interrupted by some failure. In 3 phase systems, a fault may involve one or more phases and ground, or may occur only between phases. In a "ground fault" or "earth fault", current flows into the earth.

In a polyphase system, a fault may affect all phases equally which is a "symmetrical fault". If only some phases are affected, the resulting "asymmetrical fault" becomes more complicated to analyse. The analysis of these types of faults is often simplified by using methods such as symmetrical components.

Due to the fault,a number of power system variable such as current,voltage,frequency,power factor etc. changes from a predefined range of values.

When a symmetrical 3-phase fault occurs at the terminals of a synchronous generator, the resulting current flow in the phases of the generator can appear as shown. The current can be represented as a transient DC component added on top of a symmetrical AC component. Before the fault, only AC voltages and currents are present, but immediately after the fault, both AC and DC currents are present.

Faults involving ionized current paths are also called transient faults. They usually clear if power is removed from the line for a short time and then restored

Types of fault:

Open circuit fault
Inter turn fault
Short Circuit fault

Open circuit fault:

This type of fault might occur due to incomplete switching of the circuit breaker and isolator etc. Due to this fault, no current flows through the desired path at desired time.This type of fault is considered less severe than short circuit fault.

Inter turn fault:

This type of fault is due to insulation failure in devices like transformers,motors,generators etc.Due to this fault,current drawn by the device increases from it's nominal(rated) value.

Short Circuit Fault:

The fault in which abnormally high current flows in a undesired least impedance path.High current flows due to this type of fault.So this type of fault is a more severe fault.There are two types of short-circuit fault:

Symmetrical fault
Unsymmetrical fault

Symmetrical fault:

A symmetric or balanced fault affects each of the three phases equally. In transmission line faults, roughly 5% are symmetric.They are simpler and easier to analyse because analysis of one phase will be sufficient for three phase system.

Asymmetric fault:

The unbalanced fault does not affect each of the three phases equally. Common types of asymmetric faults are:

line-to-line
line-to-ground
double line-to-ground
L-L & L-G fault

Causes of Faults:

Lightening
Vehicle colliding with tower or poles
Trees falling across the line
Improper size of conductor or insulator
Deterioration of insulation to age
Birds shorting lines

Effect of fault:

Faults may block the flow of power in the desired path.
Faults may cause the 3 phase system to be unbalanced.
Fault cause the large current resulting in overheating of the power system equipment.
Fault can rise or drop the system voltage out of acceptable range.
The fault may cause the loss of synchronism of interconnected power system.
The fault may cause fire hazards.

Lesson

Power system Fault Calculation

Subject

Electrical Engineering

Grade

Engineering

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