ELECTROMAGNETIC CONTROL SYSTEMS

An electromagnetic control system activates the various parts of a machine, at the right moment and for the right amount of time, ensuring that the machine functions properly.


-Cam switch controller: the shape of a cam allows us to control the moment and duration of an activity.

-Limit switches: the switch is activated when the float rises to a certain level. When the wáter level goes down, the switch returns to its original position and the pump turns on again.

There are two types of limit switch: normally closed and normally open.

ELECTROMAGNETIC MECHANISMS

1.Electromagnetic generators
They transform mechanical energy into electricity. Generators that produce direct current are called dynamos, and those that produce alternating current are called alternators.


-Dynamo: consists of a magnet and a rotary coil, that have, at the end, two semi-circular conductors, wich form the commutator.

-Alternator: is almost identical to a dynamo, except for the commutator, wich consists of two metallic rings connected to carbón brushes.

2.Electric motors
Is a device that can transform electrical energy into movement.

3.Relays

Is an electromagnetic component that works as a switch. When electricity passes through the coil, it acts like a magnet.

EFFECTS OF ELECTRIC CURRENT

1.Heat
The energy that an electric current produces as heat is called Joule Effect. It is exprssed by the following formula:              E = I(square) x R x t


2.Light
There are various ways that electricity can be used to produced light:

• Incandescent bulbs.When an electric current passes throughthe metallic filament of a light bulb, it produces light.

• Fluorescent tubes. When an electric current passes through the filament, electrons are emitted into the inert gas.

• Light-emitting diodes (LED). When electricity is applied to the LED, the electrons and holes cross over into the active layer, where they combine and produce photons, or particles of light.

3.Electromagnetic effect

Michael Faraday discovered that electricity could be generated by using a magnet and an electrical conductor. This principle allows us to build dynamos and alternators.

4.Sound
We can transform electric current into sound by using electromechanical devices, such as bells and buzzers. Some of these devices are based on the piezoelectric effect.

TYPES OF CURRENT

1.Direct current
We have direct current when the electrons always flow in the same direction with the same current.


2.Alternating current
In this case, the flow of electrons changes direction 50 times every second. In addition, the electric current is not always the same.

The variation of any electrical parameter over a period of time is an electric signal.


The average power of alternating current is equal to the direct current that is needed to produce the same effect. In this case of an alternating sinusoidal current, the average power would be as follow:

V(ef)=V(max)/square root of 2

Alternating current can be increased or decreased by a transformer(V1/V2=n1/n2).

TYPES OF CIRCUITS

1.Series circuit

Two or more elements form a series circuit when the output of one element provides the input for the next element.

To calculate the total resistance of a series circuit, we add the resistance values of each load:

R=R1+R2+R3...

2.Parallel circuit 

In a parallel circuit, the various components share the same input and output.

The equivalent resistance of this type of circuit would be:

1/R=1/R1+1/R2+1/R3...

3.Combination circuit

A combination circuit has some elements connected in series and other elements connected in parallel.