Measurement and Detection Devices: Types and Uses
Types of Measurement and Detection Devices
Detection Devices
Detection devices are responsible for perceiving the proximity of an object or its position. If the detection is performed by physical contact with the object, they are electromechanical switches. These are the most used position switches and they detect the position of an object. If the detection is done without physical contact, it is called proximity detection. Within the latter, there are AC, DC, and photoelectric types.
Measuring Apparatus
These devices are classified according to the magnitude to be measured:
- Voltmeter: To measure voltage.
- Ammeter: To measure electric currents.
- Wattmeter: To measure power output.
They can have an analog or digital scale.
Electromechanical Switches (Position Switches)
These are responsible for transmitting data to the command circuit about the presence or absence of an object or a person’s position on a machine. They signal the end of an action.
Constitution of a Position Switch
- Ancillary Contacts: Also for opening and closing control circuits. They can be opened or closed at rest.
- Head: This is responsible for performing the commutation of the auxiliary contacts by an external action.
- Body: This is where the auxiliary contacts are located and can be made of plastic or metal.
- Spring: This is in charge of returning the switch to its rest position.
Photoelectric Sensors
Types of Detectors
By blocking or interruption of emitted light, there are 3 types:
- Barrier System: This consists of a transmitter and a separate receiver. It has a wide reach.
- Reflex System: This consists of a transmitter-receiver in the same detector. It uses a retroreflector mirror as a reflector of light.
Constitution of a Photoelectric Detector
- Sender: Emits red or infrared light using an LED device.
- Receiver: Receives light emitted or reflected by using an electronic device called a phototransistor.
- Amplifier: Increases the weak signal received.
- Output: Enables or disables the amplifier output signal.
Electrical Boxes
These contain, in an orderly manner, all maneuvering and protection devices, as well as automatic electric measuring and control devices.
Functions of an Enclosure Box
- Contain protective devices and measuring instruments.
- Protect people against isolation defects.
- Protect the contents against the ingress of solids and liquids.
- Facilitate the carrying out of any repair or modification.
Constitution of an Electric Box
- Electric Box: Contains the operating devices and protective measures.
- Uprights: These are elements of the frame where the perforated panel or rack is screwed.
- Perforated Panel: Elements are mounted on this panel, designed to be placed on the frame.
- Profiles: Maneuvering and protection devices are placed here.
- Horizontal Cable Tray: Carries cables from one device to another horizontally.
- Connection Terminals: To connect external receivers or detectors.
- Vertical Cable Tray: Carries cables from one item to another vertically.
- Electric Cables: Interconnect the various devices.
- Door: Provides access to the automation and maintenance devices.
Types of Boxes
- Metal Caskets: Made from sheet steel with welded reinforced gaskets. They are used in industrial installations.
- Insulating Box: Made of insulating material based on polyester and fiberglass. They are robust and withstand very aggressive environments.
- Cabinets: A single body made of steel with gray paint, designed to be supported on the floor by anchors.