Basic Switch Function

Switch Action that are used to make contact for a brief period of time or as long as the button is pressed.

Switch Action that maintains the contact until it is forced to the other position.

Type of Switch that are physical, which must be activated by moving, pressing, releasing, or touching its contacts.

Type of Switch that do not require any physical contact in order to control a circuit. It is activated by semiconductor action.

Part of the switch where the switch armature is connected into.

The closed position of the switch.

This is the basic ON and OFF switch consisting of one input contact and one output contact.

This switch has three terminals: one is input contact and remaining two are output contacts.

This switch consists of four terminals: two input contacts and two output contacts. It behaves like a two separate SPST configurations, operating at the same time.

Two input contacts are connected to the one set of output contacts in one position and in another position, input contacts are connected to the other set of output contacts.

Select the type of switch.

Select the type of switch.

Select the type of switch.

Select the type of Switch

Style of Switch which is manually actuated (or pushed up or down) by a mechanical handle, lever or rocking mechanism. These are commonly used as light control switches.

Select the STYLE of Switch

Select the STYLE of switch.

Select the STYLE of switch.

Operated by the presence of an object or by the absence of objects or by the motion of machine instead of human hand.

These switches consist of a bumper type of arm actuated by an object. When this bumper arm is actuated, it causes the switch contacts to change position.

Select Style of Switch.

Select Style of Switch.

Style of Switch used for complex circuits. Commonly found on ceiling fans.

Style of Switch made up of a set of switches in a single unit, usually mounted on a PCB or Breadboard.

Switch is Normally Open, Coil is not Energized, Bulb is Off, Relay is _________.

Switch is Normally Closed, Coil is ______________, Bulb is on, Relay is closed.

Category of Transducer which requires an external power output is a measure of some variation, such as resistance and capacitance. (Ex. Condenser Microphone)

Category of Transducer which does not require an external power and they produce analog voltage or current when stimulated by some physical form of energy. (Ex. Thermocouple).

A kind of Temperature Transducer where when two wires with dissimilar electrical properties are joined at both ends and one junction is made hot and the other cold, a small electric current is produced proportional to the difference in the temperature.

A kind of Temperature Transducer where when two wires with dissimilar electrical properties are joined at both ends and one junction is made hot and the other cold, a small electric current is produced proportional to the difference in the temperature.

In a thermocouple, the relationship is nearly LINEAR over the operating range. The actual characteristic and suitable operating temperatures depends upon the metal used in the wires.

It is important that thermocouples are standard so that the same EMF will NEVER represent the same temperature.

Thermocouples come in several forms. They may be wires insulated from each other or plastic or fiber glass materials. For ___________________, the wire pairs are put inside a tube with mineral insulation.

For _________________ of thermocouples, the sensors comes in a metal enclosure such as stainless steel.

THERMOCOUPLE have a wide range of temperature from as low as 270°C up to as high as 2700 °C.

Magnitude of the thermal EMF depends on the WIRE materials used and on the temperature between the junctions.

Standard metals and pairs for thermocouple constructions known as type K

Standard metals and pairs for thermocouple constructions known as type J

Standard metals and pairs for thermocouple constructions known as type T

Standard metals and pairs for thermocouple constructions known as type S, R & B

A Thermocouple Alloy Composition consisting of 90% nickel and 10% chromium.

A Thermocouple Alloy Composition consisting of 95% nickel, 2% manganese, 2% aluminium and 1% silicon

A Thermocouple Alloy Composition consisting of 45% nickel and 55% copper

During experiments with a copper – constantan thermocouple, it was found that c = 3.75 x 10¯² mV/°C and k = 4.5 x 10¯⁵ mV/°C². if T1 = 100 °C and the cold junction, T2 is kept in ice. Compute for the resulting EMF.

Suppose you have a copper–constantan thermocouple with the coefficients c=0.02mV/°C and k=0.0001mV/°C2. The hot junction (T1​) is maintained at a temperature of 200°C and the resulting EMF is measured. Determine the temperature (T2​) of the cold junction if the EMF generated by the thermocouple is 5mV.

A type of temperature transducer that works on the principle that the electrical resistance of a conductor change with temperature.

Applications of NTC Thermistor (Select all that Apply)

Applications of PTC Thermistor (Select All that Apply).

A platinum resistance thermometer has a resistance of 150 Ω at 20°C. Calculate its resistance at 50°C, if α20 = 0.00392

A platinum resistance thermometer has a resistance of 200 Ω at 25∘C. The temperature coefficient of resistance at 25∘C, denoted as αlpha(25)​, is 0.005 °C−1. Calculate the resistance of the thermometer at 40∘C.

These are thermometers filled with either a liquid such as mercury or an evaporating fluid such as used in refrigerators.

These Instruments are robust and used over a wide range. They can be fitted with electric switches to set off alarms.

The strip is twisted into a long thin coil inside a tube. One end is fixed at the bottom of the tube and the other turns and moves a pointer on a dial.

It is a hollow tube with an elliptical cross section. When a pressure difference exists between the inside and outside, the tube tends to straighten out and the end moves.

The movement is usually coupled to a needle on a dial to make a complete gauge. It can also be connected to a secondary device such as air nozzle to control air pressure or to a suitable transducer to convert it into an electric signal.

A window in the outer case allows pressure to be indicated. This type is usually used in hydraulics where the ability to withstand shock, vibration and sudden pressure changes is needed (shock proof gauge).

It is made of several capsules. These are hollow flattened structures made from thin metal plate. When pressurized, it expands and produces mechanical movement.

These are similar in principle to the bellows, but is usually very thin and perhaps made of rubber. It expands when very small pressures are applied.

If the bellows is encapsulated inside an INNER CONTAINER, the movement is proportional to the difference between the pressure on the inside and outside.

Examples of Pressure Transducers (Select all that Apply)

Kinds of Speed Transducers (Select All that Apply).

These Transducers use a light beam and a light sensitive cell. The beam is either reflected or interrupted so that pulses are produced for each revolution.

It uses an inductive coil placed near to the rotating body. A small magnet on the body generates a pulse every time it passes the coil.

Very often it is built into electric motors to measure their speed. The frequency of the voltage represents the speed of rotation. The frequency must be counted and processed.

In a magnetic pick up, if the body is made of ferrous material, it will NOT WORK without a magnet.

In optical types, ELECTRONIC PROCESSING is required to time the pulses and turn the result into an analog or digital signal.

On magnetic pick ups, a discontinuity in the surface such as a NOTCH will cause change in the magnetic field and generate a pulse.

Type of flow meters that have a mechanical element that makes a shaft of the meter rotate once for an exact known quantity of fluid.

_______________ type consists of two rotors with lobes. When fluid is forced in, the rotors turn and operate the indicating system.

The flow of the fluid is inferred from some effect produced by the flow. Usually this is a rotor which is made to spin and the speed of the rotor is sensed mechanically or electronically.

This has an axial rotor which is made to spin by the fluid and the speed represents the flow rate. This may be sensed electrically by coupling the shaft to a small electric tachometer.

The jet of fluid spins around it and the speed of the rotor is measured mechanically or electronically.

Often this consists of a magnetic slug on the rotor which generates a pulse of electricity each time it passes the sensor.

In variable area types of flow meters, this is inside a tapered tube. The fluid goes through the annular gap around the edge of it.

In a float type of variable flow meter, because the tube is tapered, the restriction is INCREASED as the float moves up. Eventually a level is reached where the restriction is just right to produce a pressure force that counteracts the weight of the float.

It is aligned inside a hole or orifice. A spring holds it in place. The flow is restricted as it passes through the gap and a force is produced which moves the plug.

Because it is tapered the restriction changes and the plug takes up a position where the pressure force just balances the spring force. The movement of the plug is transmitted WITH A MAGNET to an indicator on the outside.

The type of flow meter wherein the working principle is that something makes the velocity of the fluid change and this produces a change in the pressure so that a difference in pressure is created. It uses Orifice Meters, Venturi Meters, Nozzle Meters, or Pitot Tubes to convert flow rate.

In a flow measurement system, the volume flow rate (Q) of a fluid is measured using a differential pressure (ΔP) across an orifice plate with a meter constant (k) of 0.025 m3/s. Calculate the volume flow rate when the Pressure changes from 100Pa to 300Pa.