Simple FanRegulator Circuit

Simple Fan Regulator Circuit


Have you ever come across using a conventional fan voltage regulator to control the speed? Such type of regulator is called as resistance regulator which works on the principle of a rheostat or a resistance potential divider arrangement.

As the steps (of the knob on a regulator box) are decreasing, means that you are actually increasing the resistance of the circuit and hence the lower power is applied to the fan so that it becomes slower.

Obviously the power consumption by the fan will be less at lower speeds by this arrangement, but this is not an energy saving method. The voltage drop across the resistance is converted into heat losses (I2R) so the energy is dissipated in the form of heat.

This wastage of energy is more at high resistance or lower speed condition. Therefore, conventional fan voltage regulators have more energy losses.


conventional voltage regulator

Simple Electronic Voltage Regulator

Due to the advancement in power electronic technology, the alternative design of fan regulator (voltage regulator) can be easily implemented to reduce the energy losses that are caused by conventional voltage regulators. This type of voltage regulator is an energy saving device which uses TRIAC, DIAC and potentiometric resistance.

This method provides the step less control of the fan speed by deriving the required amount of power from the main supply at a given instant .Hence the power is conserved rather than wasted unnecessarily. Let us discuss briefly about this voltage regulator circuit and its working.


Electronic voltage regulator

Now we are going to build the voltage regulator circuit which is generally used to control the speed of the fan in our homes or offices. As we know that by varying the firing angle of the traic, the power applied through the load is controlled which is nothing but a concept of power control using TRIAC.

The same principle is applied to the voltage regulator circuit which we are going to discuss.

Required Components for Voltage Regulator Circuit

Resistor R1 – 10 K ohm
Variable resistance or potentiometer R2 – 100 K ohm
Polyester capacitor C1 – 0.1 µ F (For operating range of 500 V or above)
DIAC, D1 – DB2
TRIAC, T1 – BT136
A single phase ceiling fan or AC motor – 220 V, 50 Hz (ranges below 200 Watts)
Voltage Regulator Circuit Connection

Recognize the terminals of all the components for positive and negative terminal connections. Choose the ceiling fan or any AC motor provided it should be rated below 200 watts (According to the values of the components selected)
Take a zero board or printed circuit board (PCB) and connect the circuit as given in the below diagram.
The firing circuit consists of resistor R1, potentiometer R2, capacitor C1 and a DIAC. Connect the one terminal of the DIAC to the voltage divider combination of resistors and capacitor as shown in figure.
Consider the data sheet of TRIAC BT 136 for recognizing the terminals of TRIAC and to know the other detailed information. Connect MT1 terminal to the neutral while MT2 to one end of the AC motor or load. And connect the gate terminal to the other end of DIAC.
Connect the load or ceiling fan between the Phase or Line terminal of the AC power supply and MT2 terminal of TRIAC.
Circuit Diagram of Voltage Regulator using TRIAC,DIAC:



Operation of the Electronic Voltage Regulator Circuit

Before giving the power supply to the circuit, keep the variable resistor or potentiometer in maximum resistance position so that no triggering is applied to TRIAC and hence the TRIAC will be in cutoff mode.
Turn ON the power supply of the circuit and observe whether the fan is in standstill condition or not. Vary the potentiometer position slowly so that the capacitor starts charging at the time constant determined by the values of R1 and R2.
Once the voltage across the capacitor is more than the break over voltage of the DIAC, DIAC starts conducting. Thus, the capacitor starts discharging towards the gate terminal of TRIAC through DIAC.
Therefore, TRIAC starts conducting and hence the main current starts flowing into the fan through the closed path formed by TRIAC.
By varying the potentiometer R2, the rate at which capacitor is going to be charged get varied this means that if the resistance is less, the capacitor will charge at a faster rate so the earlier will be the conduction of TRIAC.
As the potentiometer resistance gradually increases, the conduction angle of TRIAC will be reduced. Hence the average power across the load will be varied.
Due to the bidirectional control capability of both TRIAC and DIAC, it is possible to control the firing angle of the TRIAC in both positive and negative peaks of the input.
Note:

As a safety measure, test the good working condition of this circuit by applying a low voltage supply like 24V AC or 12 V AC with a small load like a low wattage bulb before connecting to the mains supply.
If the load exceeds 200 watts, choose the higher watt capacity TRIAC in place BT 136 TRIAC.
Advantages of voltage regulator circuit

Continuous and step less control of the fan speed is possible
Power saving is achieved at all the speeds by minimizing the energy losses
Simple circuit which requires less number of components
Efficient as compared with resistive type due to lower power consumption
Cost-effective

Data Interpretation Tricks

Data Interpretation Tricks

Data Interpretation is easily the most neglected topic during CAT preparation. Most often, people assume that there is nothing they can do to improve their scores in DI and hence, do not try to work on this topic. Many people simply do not know how to prepare and hence, avoid this section. However, DI contains 10 out of 60 questions in CAT and properly attempting it can easily be the difference between 90 percentile and 99 percentile or above. With this in mind, we bring to you 10 tips to improve Data Interpretation Score in CAT.
1. Read the question carefully

The first and the most important step in solving any Data Interpretation question is to read the question carefully. You should read all the data that comes with the graphs or table in the question. Many a times, the data given below the graph turns out to be more important than most of the numbers in the graphs.

2. Analyze the Data Carefully

The next step should be to analyze the given graph/data carefully. Do not try to see the questions first and find out the answers accordingly. You will waste your time if you follow that method. Try to understand the graph. What is it about? Which years does it cover? Is the data in absolute terms or in percentage terms? What do the two axis signify?, etc. Look at the statistics for each graph, chart, table or pie diagram. Look carefully at the labels. Make sure you understand the central them of the data.

3. Don’t worry about too much data

Try to understand the question. Sometimes, the question contains lots of data that is unrelated and not required for answering the questions. When you look at the question you may get discouraged by the lengthy tables or by the amount of information below the graphs. But, if you were to understand what the data is about and then look at the question, you may find that you only have to use part of the data. Hence, it is important that you do not get disheartened by the size of the data and skip the question without looking closely at it.

4. Skip Questions that need too much Calculation

Some questions ask too much from you. They require lots of calculation in order to be solved. These questions are known as the speedbreakers. Such questions are best left alone, at least in the first round. Once you have finished solving all the easy questions and still have time for the section to end, you should attempt these questions. If you try such questions, you will lose your precious time on them and may not be able to attempt some simple questions that may follow. By attempting easy questions first, you will improve Data Interpreatation Score in CAT

5. Avoid Unnecessary Calculations

We have a habit from our school days to solve questions in a step by step method. This is a very good habit for school exams but a really bad habit when it comes to attempting CAT papers / mocks. There are many unnecessary calculations that we do which cost us a precious few seconds per question. Sometimes, there are many steps that can be skipped but we still do it as we are trained to solve in a step by step method. Learn to skip those steps.

6. Pay close attention to the units used

Sometimes, the questions will use a different unit for the question and another unit for the data. For example, the data given may be about sales volume in Millions. However, the question may ask about sales volume in lakhs. If you do not pay close attention to the unit, you may chose the wrong answer. Another question may talk about two roads for example and may give the time in hours in one case and minutes in another. Always convert the units into the ones asked. So, if the question asks how many minutes it will take, convert the data given in hours into minutes. Or if the question asks in hours, convert the data in minutes to hours.

7. Learn to Approximate

CAT is not about finding the exact answer always. Most of the times, the options given are far enough from each other to give you enough room for approximation. So, for example, if you are asked to divide 542678/181234, you can easily approximate that the answer will be somewhere around 3 by looking at the first 2 numbers only. 54/18 is 3. So, instead of dividing it and finding the accurate answer, try to find an appproximate answer. This will give you the correct answer more often than not. If however, the options are close, you will still be able to eliminate 1 or 2 options easily.

8. Do not assume anything

Sometimes there are questions which will ask us to find out something holistic data for which is not available. Always be alert enough to see whether the data given is enough to answer the question or not and do not go forward with answering the questions based on assumptions.

There is a joke on this which I am sure most of you may have heard. It goes something like this:

A man was driving with his son to some destination. Midway, they had an accident and the son was injured. The father took him to the hospital. The doctor there saw the boy and said “He is my Son”. How is this possible?

—> The Doctor is his mother.

Female Doctors do exist.

The joke relies on the fact that most people would assume the doctor to be a man. This leads to this riddle/joke’s punchline.

9. Dont attempt DI sets in the last 10 minutes

Last 10 minutes often bring with them anxiety and solving DI questions requires a cool head which aids analysis of data. Solving a set may prove costly as panic may kick in and if one is not able to solve the set it may lead to loss of time which otherwise could have been devoted to singlets.

10. Learn to skim through data

In recent years CAT/XAT have been giving sets which have a lot of data in them and all the data is not required to solve the questions. Skimming through the data and avoiding entanglement becomes an important part of the process. So focus on what is required in the question rather than forming tables/ consolidated form for all the data.