Adjustable AC current circuit breaker
k.Murali krishna
Introduction
A circuit breaker is an electrical switch intended to protect an electrical circuit or device from damage caused by excess current flow or in a short circuit condition . Its fundamental purpose is to interrupt current flow . Basic circuit breakers include a simple fuse and a normal MCB (miniature circuit breaker). These are designed for a fixed rated current value in terms of amperes.
Here is represented an AC circuit breaker with adjustable current by the user . The circuit is simple, wide range, low cost and user friendly . The user can select his maximum current value ranging from milli amperes to few amperes . A simple electronic circuit compares the flowing current
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Fig 5 : transformer before and after winding
Setting the circuit using 3 pin connector and multimeter :
Step 1:select the range switch depending on laod .LOW =300mA to 1A,HIGH =1A to 5A
Sep 2: turn current adj pot to maximum
Step 3: connect to AC IN and load ( device) and switch on
Step 4: using multi meter measure the voltage at pin 3 of op-amp provided at connector 1
Step 5: turn the pot 1 and set the voltage just nearer to voltage of pin 3 of op-amp.
Now the circuit is ready. When the voltage at pin 3 of op-amp increases than the voltage at pin 2 then the is cut off.
Setting the circuit using the green LED:
Step 1: select the range switch depending on laod .LOW =300mA to 1A,HIGH =1A to 5A
Step 2: press reset .
Step 3:turn the pot to MAX.
Step 4: connect to AC IN and load ( device) and switch on .
Step 5: slowly turn the pot from MAX to MIN (clockwise ) until the the load gets turned off.
Step 6: now slowly turn the pot slightly( little) backward in anti clockwise and press reset .
Now the circuit is ready for your set load .
Test points :
TP0: GND
TP1: DC voltage corresponding to the current passing through N3 winding
TP2:DC voltage 1/3 times of
5. Put the stirring wire through the second hole of the stopper. Insert the stopper, thermometer, and wire into the test tube. Make sure that the thermometer bulb is below the surface of the solution.
== = == 1. Set up the equipment as shown in the diagram on the floor.
I can do this by setting up the diagram above. You need to get a
it to a 5V power supply as a more convenient way of measure. As the
Plan 1. Collect 4 different sized beakers 2. Boil some water in the kettle 3. Pour 50ml into each beaker 4. After 1 minute check temperature 5.
Next, repeat steps 7-11 4 times however this time you don’t do it with hot water you do it with the cold water. To keep the cold water cold put ice cubes in the water if it starts to become warm. 14.
Step 3: Next loosen each lug nut two full turns. Never remove the lug nuts completely during this step.
5.) One at a time, place your test tubes in the water bath and heat the first test tube to 25 , the second to 50 , the third to 75, and the last to 100 degrees c. Remeber to stir with your stirring rod every so often.
Heat the contents of the pan over a low flame and bring it to a boil.
The voltage and current for the wire were then recorded, and. recorded again when the variable resistor's slider was moved to the. middle and again when the slider moves to the end. F The Power was turned off while another was added to avoid. overheating.
Circuit breakers and fuses provide equipment and installation protection and operate only in response to an electrical overload or short circuit. Hence these devices cannot detect earth fault currents below their operating current. If they are the only means of protection, it is possible for sufficient earth fault current to flow undetected to constitute an electrical hazard (fire and electrocution).
8. Continue to heat the crucible, occasionally lifting the lid with tongs to provide oxygen for the reaction
2. In the large beaker, put water and boil it completely. After that, remove the beaker from heat. 3. Sample tubes (A-D) should be labeled and capped tightly.
Electricity and electrical components are a major part of our lives today. Our lives pretty much come to a halt if there is a power outage or if our electrical devices stop working, sometimes we even start panicking because we are so dependent on these components that we cannot afford to lose them and their importance and use only increases as time passes. We all use these electrical devices and also electricity itself but most of us do not think about the math and physics that works behind all of these things.
All useful generators of electricity come in two basic forms, alternating current and direct current. Direct current (dc) comes from generators that do not change in polarity, always producing a positive charge. In alternating current (ac) the polarity of the terminals is always changing from positive to negative. Thus you are left with alternating current flow. There are different ways of measuring and generating alternating and direct current.