| actuate |
To make a device or machine operate. Selector switches actuate contacts. |
| actuates |
Makes a device operate or run. Pushbutton operators actuate electrical contacts. |
| actuator |
The part of a limit switch that comes into contact with an object and triggers the switch. Limit switch actuators come in different styles: rotary levers, forks, plungers, flexible loops, and spring rods. |
| air compressors |
A component that pressurizes ambient air. Air compressors direct pressurized air into pneumatic systems. |
| automatic control |
A control device that runs independently of an operator. Automatic control devices receive signals from other devices that tell them when to start a process. |
| automatic inputs |
A control device that is set to determine and manage each step in a process independently. Automatic inputs include pressure switches, flow switches, and temperature switches. |
| bellows |
A cylindrical device with several deep folds that expand or contract in response to pressure. Bellows are usually used at medium pressure. |
| bimetallic sensor |
Also known as a bimetallic strip, a sensor made of two unlike bonded metals that expand at different rates when heated. Bimetallic sensors provide a physical signal that the sensor converts into an electrical signal. |
| bimetallic strip |
Also known as a bimetallic sensor, a sensor made of two unlike bonded metals that expand at different rates when heated. Bimetallic strips provide a physical signal that the sensor converts into an electrical signal. |
| capacitive proximity switches |
A control device that is triggered when it detects either conductive or nonconductive substances. Capacitive proximity switches are able to detect both solid and liquid materials. |
| capillary tube sensor |
A sensor that changes internal pressure when temperature changes. Capillary tube sensors use temperature sensitive liquid. |
| chatter |
The occasional unwanted vibration between components. Chatter decreases machining productivity, negatively impacts surface quality, and increases tool wear. |
| circuit conditions |
The different options that selector switches allow technicians to choose. Circuit conditions may include options such as "left/right," "up/down," "manual/automatic," and "on/off." |
| CNC machines |
Computer numerical control machine. A machine controlled by a computer that performs a series of operations. CNC machines contain control devices such as switches to help them function safely. |
| coils |
Wire that is wrapped around a magnetic core. Coils conduct electrical current in a circuit. |
| cold junction |
The end of a thermocouple that provides a reference point. The cold junction is held at a constant temperature. |
| contact |
A conductive metal part that opens or closes a circuit by separating from or touching a matching part. Contacts are components of electrical circuits. |
| contact blocks |
Pushbutton components that hold contacts and are activated when pushbuttons are pressed. The most common contact block has one normally open (NO) and one normally closed (NC) contact. |
| contactor |
A device that uses a small control current to energize or de-energize a load. Contactors can handle high amounts of current and are also combined with overload relays to create motor starters. |
| control devices |
Any input device that controls the flow of current in a circuit. Control devices determine when loads are energized or de-energized. |
| control relay |
An electrical switch that opens and closes a circuit. Relays can open or close one or many sets of contacts. |
| cooling lines |
A passage through which cooling fluid is circulated. Cooling lines assist in maintaining the desired temperature in a system. |
| current |
The flow of electricity through a circuit. Current in a circuit can be controlled by control devices. |
| deadband pressure |
The amount of pressure that must change before pressure switch contacts reset after actuation. Deadband pressure is also referred to as differential pressure. |
| diaphragm |
A spring-loaded valve mechanism that moves in response to variations in pressure in a pneumatic system. The diaphragm is a flexible membrane that responds to pressure changes. |
| digital multimeter |
DMM. A device that can measure voltage, current, or resistance. A digital multimeter is the most versatile and common meter used today for electrical maintenance. |
| eddy currents |
A magnetic current created by sensor vibration. Eddy currents flow out and around the head of a sensor. |
| electrical circuit |
A controlled path that contains electrical current. Electrical circuits are controlled by control devices. |
| electrical control devices |
A type of control device that senses the presence of an object without touching it. Electrical control devices include proximity switches and photoelectric switches. |
| emergency stops |
E-stop. A switch or button that brings a machine to a safe, rapid stop. Emergency stops are often mushroom button operators. |
| extended button operator |
A pushbutton operator whose button extends beyond its guard. Extended button operators are used in situations where accidental startup is not dangerous. |
| float |
A device used in switches that floats on liquid. Floats rise or fall based on the level of the liquid. |
| flow switches |
A switch that detects the movement of any fluid, such as liquid, gas, or air, in a system. Flow switches are commonly used in fluid pumps and air compressors. |
| flow switches |
A switch that detects the movement of any fluid, such as liquid, gas, or air, in a system. Flow switches are commonly used in fluid pumps and compressors. |
| fluid pumps |
A mechanical device that is used to move liquids or gases. Fluid pumps are used in hydraulic and pneumatic systems. |
| flush button operator |
A pushbutton operator that has a guard ring that sits at the same level as the operator. Flush button operators are used in situations where accidental startup is dangerous. |
| guard ring |
The piece of circular material surrounding a flush button operator. Guard rings prevent unintentional starting of an operation or machine. |
| hot junction |
The end of a thermocouple that measures temperature. The hot junction is exposed to the elements. |
| hydraulic |
A system that uses liquids to transmit power. Hydraulic systems rely on fluid force to run different systems. |
| indicator light |
A device that lights up to signal something. Indicator lights may flash when normally open (NO) contacts close. |
| inductive proximity switches |
A control device that is triggered when it detects a conductive substance. Inductive proximity switches operate using eddy currents. |
| inputs |
A device that enters in and contributes to a process. Inputs are a type of control device. |
| jog/off/run |
A common circuit condition that lets a technician run a machine intermittently, power it down, or run it consistently. "Jog/off/run" is a common circuit condition on a three-position selector switch. |
| jog/run |
Circuit conditions that allow a technician to make a machine function intermittently or consistently. The "jog/run" choice of conditions is the most common set of conditions on a two-position selector switch. |
| legend plate |
The part of a switch that displays the function of the switch's operation. Legend plates surround pushbuttons. |
| level switches |
A device that detects the height of a liquid or solid in a tank or another type of vessel. The most common type of level switch is the mechanical level switch. |
| light source |
A device that emits beam of light received by a photosensor. Light sources are used to trigger photoelectric sensors. |
| limit switch actuator |
The part of a limit switch that contacts an object and triggers the switch to perform an action. Limit switch actuators come in two different categories: rotary and plunger. |
| limit switches |
A switch that detects the presence an object by physically touching it. Limit switches have a variety of actuators that come into contact with an object. |
| load |
A device that converts electricity into light, heat, or mechanical motion. Loads are components of electrical circuits. |
| lower set level |
The minimum level at which a technician has set a pressure switch to operate. Once pressure has reached the lower set level, contacts will close or open and remain in that condition until pressure rises. |
| manual control |
A control device that requires an operator to activate or deactivate it. Manual control devices include pushbuttons. |
| manual inputs |
A control device that requires individuals to press a button or turn a switch. Manual inputs include pushbuttons and selector switches. |
| mechanical control |
A device that must make physical contact with an object to operate. Mechanical control devices include limit switches. |
| mechanical control devices |
A device that physically contacts objects. Mechanical control devices include limit switches, flow switches, and level switches. |
| mechanical inputs |
A control device that must touch an object in order to detect it. Mechanical inputs include limit switches. |
| mechanical level switch |
A device that uses a float to trigger electrical contacts. Mechanical level switches are used to detect liquid levels when they reach a set height. |
| motor starter |
An electrically operated switch that uses magnetic induction to provide the startup current for a motor. |
| mushroom button operator |
A pushbutton operator that extends beyond its guard. Mushroom button operators have large, rounded heads and can be easily accessed. |
| NC contacts |
Normally closed contacts. Electrical devices that allow electricity to flow. When an NC contacts open, electricity stops flowing. |
| NO contacts |
Normally open contacts. Electrical devices that prevent electricity from flowing. When NO contacts close, electricity starts flowing. |
| normally closed |
NC. An electrical contact that allows electricity to flow. If an NC contact opens, electricity stops flowing. |
| normally open |
NO. An electrical contact that does not allow electricity to flow. If an NO contact closes, a circuit may be formed. |
| operator |
The part of a switch that is pressed, pulled, or turned by an individual operating the circuit. Operators come in a variety of styles and sizes. |
| output |
An activity or result of a process. Outputs triggered by contacts closing can range from the flashing of an indicator light to the sounding of a warning bell. |
| paddle |
A hinged actuator used in many types of flow switches. The flow of fluid deflects the paddle, actuating the flow switch contacts. |
| photoelectric sensors |
A control device, also known as a photoelectric switch, that detects the presence of an object through the use of a beam of light. When the beam of light is interrupted, the sensor sends a signal through the circuit that affects the operation of the machine in a specific way. |
| photoelectric switches |
A control device, also known as a photoelectric sensor, that detects the presence of an object through the use of a beam of light. When the beam of light is interrupted, the switch sends a signal through the circuit that affects the operation of the machine in a specific way. |
| photoelectric switches |
A switch that uses a light beam to detect the presence of an object without touching it. Photoelectric switches can detect lightweight objects, heavy objects, or objects that are too hot. |
| photosensor |
A control device that detects light. Photosensors detect the presence of an object using a beam of light. |
| piston |
A piece of metal that moves up and down inside a hollow cylinder in response to a pressure change in pneumatic and hydraulic systems. Pistons may be used to transfer motion to brake components. |
| plunger actuators |
A limit switch actuator in the form of a button that is depressed to activate the switch. Plunger actuators come in three basic styles. |
| pneumatic |
A system that uses gases to transmit power. Pneumatic systems rely on gas to run a system. |
| power source |
A device that generates electricity. Power sources are components of electrical circuits. |
| pressure sensing devices |
A control device that is designed to detect a range of pressures in motor control systems. Pressure sensing devices include diaphragms, bellows, and pistons. |
| pressure switches |
A device that detects a certain amount of force and activates electrical contacts when the force is reached. Pressure switches have different sensing devices that detect pressure changes. |
| pressure switches |
A switch that detects a certain amount of force and activates electrical contacts when the force is reached. Pressure switches have different sensing devices that detect pressure changes. |
| proximity sensors |
A control device, also called a proximity switch, that uses an electronic sensing field to sense the presence of an object without touching it. Proximity sensors can detect the presence of almost any liquid or solid. |
| proximity switches |
A control device, also called a proximity sensor, that uses an electronic sensing field to sense the presence of an object without touching it. Proximity switches can detect the presence of almost any liquid or solid. |
| proximity switches |
A switch that uses an electronic sensing field to sense the presence of an object without touching it. Proximity switches can detect the presence of almost any liquid or solid. |
| pushbutton |
A manual control device that opens or closes a circuit when pressed. Pushbuttons can be normally open or normally closed. |
| pushbuttons |
Manual control devices that open or close a circuit when pressed. Pushbuttons can be normally open or normally closed. |
| receiver |
A mechanism designed to receive light. When receivers do not receive light from the photosensor, an object or person is in its path. |
| relay |
An electrically controlled mechanical device that controls one circuit by opening or closing contacts in another circuit. Relays can open or close one or many sets of contacts. |
| resistance |
The opposition to current flow. Electricity flows in the path of least resistance. |
| resistor |
A device that restricts current flow. Resistors produce work, such as heat or light. |
| rotary actuators |
A limit switch actuator with a handle that directs force in a circular motion. Rotary actuators come in a range of styles and sizes to be used in a variety of applications. |
| selector switch |
A device that can be turned to different positions to make a connection with contacts in that particular position. Selector switches allow technicians to operate machines under different conditions. |
| selector switches |
A switch that can be turned to different positions to make connections with the contacts in that particular position. Selector switches can allow technicians to operate machines under different conditions. |
| short |
A circuit where current takes a shorter, unintended path between two conductors. Shorts, also known as short circuits, cause excess current flow. |
| stop plate |
A metal guard plate connected to a limit switch that prevents damage to the switch. Stop plates keep limit switches from being forced beyond their travel limit. |
| surface grinder |
A machine that uses a rotating wheel to wear away precise amounts of a flat workpiece surface. Surface grinders rely on limit switches to keep them from being damaged. |
| switch |
A control device that can make or break a circuit by closing or opening. Switches can be manual, mechanical, or automatic. |
| temperature switches |
A switch that reacts to different heat intensities and activates electrical contacts when the temperature rises above or drops below a set level. Temperature switches are often used in heating and cooling systems. |
| thermistor |
A resistor that is temperature sensitive. As the temperature changes, the resistance of a thermistor changes. |
| thermocouple |
A temperature sensor that measures heat at a hot junction and outputs voltage at a cold junction. Thermocouples output voltage that is proportional to the measured temperature. |
| three-position selector |
A selector switch that allows you to select one of three circuit conditions. The third position is usually "off," as in "forward/reverse/off." |
| two-position selector |
A selector switch that allows a technician to select one of two circuit conditions. Common two-position selector switches are "on/off" and "forward/reverse." |
| upper set level |
The maximum level at which a technician has set a pressure switch to operate. Once pressure has reached the upper set level, contacts will close or open and remain in that condition until pressure falls. |
| workpiece |
A part that is worked on during manufacturing processes. Workpieces may be subjected to cutting, welding, forming, or other operations. |