Automation and Control Guides Page 5: 198 technical guides for choosing Automation and Control products: selection criteria, standards, common mistakes and frequently asked questions.
What Is a DIN Rail Power Supply? Types and Selection Criteria — A DIN rail power supply mounts on a 35 mm DIN rail and converts the mains voltage into a fixed DC voltage (mostly 24 V) that feeds PLCs, sensors and relay coils. What Is a Twin (Double) Push Button? Types and Selection Criteria — A twin (double) push button is a control device with two separate push buttons in one housing that fits a single 22 mm panel hole, giving two commands such as start and stop. What Is a Square DC 3-Wire Inductive Sensor? Types and Selection Criteria — A square DC 3-wire inductive sensor is a proximity sensor with a square or rectangular housing that detects metal without contact and gives a PNP or NPN output in DC control circuits. What Is a Micro Switch? Micro and Mini Switch Types and Selection Criteria — A micro switch is a small switch that changes its contact with a small actuating force and a short movement, used to detect position and open covers. What Is a PID Thermostat? Types and Selection Criteria — A PID thermostat is a digital controller that compares the measured temperature with the set value and adjusts its output with proportional, integral and derivative action to hold a narrow band. What Is a Key-Operated Push Button? Types and Selection Criteria — A key-operated push button is a panel button whose position can only be changed with a key; it is used for authorised commands such as auto-manual switching, maintenance mode and start permission. What Is an M18 DC 3/4-Wire Inductive Sensor? Types and Selection Criteria — An M18 DC 3/4-wire inductive sensor is a proximity sensor with an M18x1 threaded cylindrical housing that detects metal without contact and gives a PNP or NPN output. What Is a Process Indicator? Types and Selection Criteria — A process indicator is a panel-mount device that scales a 4–20 mA or 0–10 V transmitter signal and shows a value such as pressure, level or flow digitally. What Is a Single-Function Timer Relay? Types and Selection Criteria — A single-function timer relay is a timer relay with a fixed function where only the time is set; most models in the catalog work as on-delay relays. What Is a Head Type Temperature Probe? Types and Selection Criteria — A head type temperature probe is a J or K thermocouple or PT100 sensor whose metal-sheathed element is wired to terminals inside a connection head. What Is a General-Purpose Relay? Types and Selection Criteria — A general-purpose relay is a plug-in electromechanical control relay that changes one or more contacts when its coil is energised. What Is a PLC CPU? Types and Selection Criteria — A PLC CPU is the processing unit of a PLC that reads the inputs, runs the user program cyclically, drives the outputs and manages the communication ports. What Is a Safety Limit Switch? Types and Selection Criteria — A safety limit switch is a position switch that detects an opened machine guard or cover and breaks the safety circuit; mechanical types do this with a positive-opening contact. What Is a Soft Starter? Types and Selection Criteria — A soft starter is a semiconductor motor starter that uses thyristors to raise an induction motor's voltage gradually at start-up, reducing starting current and mechanical shock. What Is an Empty Push Button Enclosure? Types and Selection Criteria — An empty push button enclosure is a control box supplied empty, with holes ready for push buttons, selector switches and pilot lights, so you can build a control station in any layout. What Is a Perforated Power Supply? Types and Selection Criteria — A perforated power supply is a switch-mode power supply in a ventilated metal case that converts 230 V AC mains into a fixed DC voltage and is screw-mounted inside a panel or device. What Is a Switch with Terminals (Rocker Switch)? Types and Selection — A switch with terminals is a mostly rocker-type switch that snaps into an appliance housing or panel door, with cables connected to its rear tabs by faston terminals. What Is a Bayonet Type Temperature Probe? Types and Selection Criteria — A bayonet type temperature probe is a J or K thermocouple or PT100 sensor whose spring-loaded body and twist-lock cap keep its tip pressed against the bottom of the socket. What Is a Push Button Crane Pendant? Types and Selection Criteria — A push button crane pendant is a hanging control station that gives direction commands for a crane's hook, trolley and bridge movements from the floor, usually with an emergency stop. What Is a Standard (Plug-In) Relay? Types and Selection Criteria — A standard relay is an electromechanical plug-in relay used on a DIN rail socket that changes over its 1–4 contacts when a control signal reaches its coil. What Is a Control Push Button? Types and Selection Criteria — A control push button is fitted into a panel door or machine housing and manually switches control circuits such as contactor coils, relays or PLC inputs. What Is a Mechanical Switch? Types and Selection Criteria — A mechanical switch is a position switch that needs no supply and opens or closes its contact when a moving part touches its plunger, roller or lever. What Is a Servo System? Components, Types and Selection Criteria — A servo system is a motion control system of servo motor, servo drive and encoder that runs a machine axis in closed loop to a position, speed or torque command. What Is a Temperature Probe? Types and Selection Criteria — A temperature probe is a sensor that sends temperature to a controller as a thermocouple voltage or a resistance change; types include J and K thermocouples, PT100, NTC and PTC.