Single Phase Voltage Controller In ELC

Description of ELC(Electronic Load Controller) is provided which is used for micro hydropower in a country like Nepal to maintain the frequency level of the system by consuming the appropriate amount of power by dump load, thus making the power generated by system equal to sum of power consumed by dump load and consumers.

Summary

Things to Remember

1) The load controller is an electronic device that maintains a constant electric load on a generator in spite of changing user load.This permits the use of turbine with no flow regulating devices and their governor control system.

2) It is useful in micro hydropower in a country like Nepal.

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Subjective Questions

Q1:

Write short notes about Anticholinergics.

Type: Short Difficulty: Easy

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Answer: <h3>Anticholinergics</h3>
The drugs which inhibit the physiological action of acetylcholine at the receptors site.
 
<h4>Expectorants</h4>
The drugs which increase the bronchial secretion of the bronchial gland or reduces its viscosity, facilitate the removal by coughing and help loosen the thick bronchial secretions.
 
<h4>1.Ammonium chloride</h4>
Ammonium chloride is the main ingredient that is used in a productive cough. It is used as an expectorant.
 
Mechanism of action:
It is called as reflex expectorant because it directly acts as a reflex system. And claim as the promotion of the expulsion of the bronchial secretions. Expectorant doses are sub emetic but often nauseating because of unpleasant taste.
 
Indication:
<ul>
<li>To facilitate a productive cough</li>
<li>Used in making urine acid as it aid in execration of certain basic drugs.</li>
</ul>
 
Usual doses:
Adult- 300mg every 4 hourly
Child-75-150mg every 2-4 hourly
 
Contraindication:
<ul>
<li>Pulmonary failure</li>
<li>Cardiac failure</li>
<li>Serve renal failure</li>
<li>Hepatic impairment</li>
</ul>
 
Adverse effect:
<ul>
<li>Gastric irritation</li>
<li>Metabolic acidosis</li>
<li>Vomiting</li>
<li>Nausea</li>
</ul>
 
General implication:
<ul>
<li>It should be taken after a meal to avoid gastric irritation.</li>
<li>Note the rate and depth of respiration during the therapy; hyperventilation, weakness, shortness of breath are possible.</li>
<li>Administer drugs after food to reduce gastric irritation.</li>
<li>Avoid administration of milk or other alkaline solution with ammonium chloride.</li>
<li>Medicine should not be taken with diluted water and during medicine full glass of water should be given.</li>
<li>Consult the patient to take potassium containing diet to enhance potassium loss.</li>
<li>Monitor the patient intake and output properly.</li>
<li>Encourage the patient to do deep breathing and coughing exercise during therapy to ease a cough expectorate.</li>
</ul>
 
 
<h4>Vasaka</h4>
It is obtained from the plant Adhatoda vasica. They believed to increase the bronchial secretion and mucosal ciliary action.
Mechanism of action
It increases the bronchial secretion and mucosal ciliary action.
 
Indication
<ul>
<li>To facilitate a cough</li>
</ul>
 
Contraindications and adverse effect not specified
 
<h4>Sodium and Potassium citrate</h4>
It is also known as citric acid. it is used as the expectorants and urinary alkalizer.
 
Mechanism of action
It acts as the expectorants and alkalizer.
 
Indication
<ul>
<li>Cough</li>
<li>Dysuria</li>
</ul>
 
Contraindication and adverse effect not specified
 
<h4> </h4>

Videos

Anticholinergic Agents

Single Phase Voltage Controller In ELC

The load controller is an electronic device that maintains a constant electric load on a generator in spite of changing user load.This permits the use of turbine with no flow regulating devices and their governor control system.

Fig_1: Schematic of Electronic Load Controller

The basic principle of the scheme is that if the input power to the turbine Q is kept constant by allowing a constant water flow into the turbine and if the total power generation of the generator (= power of the consumer + power of ballast load) can be kept constant, then the speed of the turbine will remain constant thus by producing a constant frequency of the supply voltage

When the consumer load is maximum, the ballast load is set at zero by setting the firing angle of the AC voltage controller α = 180^o, so that the power generated by the generator is equal to the power consumed by the consumers and desired speed is set to required frequency at this condition When the consumer load decreases, the tendency would be over speeding of the turbine thus by producing the voltage at higher frequency. The electronics load controller will sense this increased frequency and by comparing it with the reference frequency f(ref), the controller will give signal to the gate pulse generator so that gate pulse generator will adjust the firing angle of AVC to increase the ballast power so that the total power of generator again remain constant and the frequency remains constant. Though power is lost in this process, but it is suitable for small-scale generation from the economical point of view(construction of governor can cost quite high).

References

1) Adhikari, Rajendra. Advanced Electronic Load Controller with voltage and frequency Droop for parallel operation of micro-hydro generators. n.d. 15 05 2016. <http://rajendraadhikari.info.np/wp-content/uploads/2013/12/scheme.png>.

Lesson

AC Voltage Controller

Subject

Electrical Engineering

Grade

Engineering

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