| Actuator
| Mechanism within the limit switch to operate the contacts. |
| Axial Approach
| Target approaches the sensor head on. |
| Cam
| Machine part that applies force to the switch actuator, causing it to move as intended. |
| Capacitance
| The ability of insulators to store an electrical charge. |
| Damping
| A loading effect due to eddy currents being induced in the surface of a sensed metallic target, causing a reduction in amplitude of the proximity sensor’s oscillator signal. |
| Dielectric
| The insulator separating the plates in a capacitor. |
| Differential
| Plunger or actuator travel from point where contacts “snap over” to the point where they “snap back.” |
| Diffuse Reflective
| Mode of detection where the sensor bounces light off the target object itself. |
| Eddy Current
| Currents induced into the body of a metallic object by an oscillating electromagnetic field. |
| Embedded
| A shielded core/coil sensor embedded in the surrounding metal. The sensor is not affected by surrounding metal. Also referred to as flush mounting. |
| Excess Gain
| Measurement of the sensing power of a photoelectric sensor to detect an object beyond the minimum required in a given environment. |
| Ferrous
| Metallic material that contains steel, nickel or cobalt. |
| Fiber Optic
| Sensor consisting of thin plastic or glass fibers for detection in very tight places. |
| Hysteresis
| The difference between the operate point (where the target is detected) and the release point (where the target is no longer detected). |
| Lateral Approach
| Target approaches the sensor from the side. |
| LED
| Short for Light Emitting Diode. A low power, no heat source of light for photoelectric sensors. |
| Light Curtain
| Specialized reflex sensor head that emits a fan-shaped beam of light. |
| Line-Powered Sensor
| A sensor that draws its operating current directly from the line. |
| Load-Powered Sensor
| A sensor that draws its operating current through the load. |
| Maintained Contact
| Sustained contact after plunger has been released, but can be reset. |
| Minimum Holding Current
| Current required to sustain a solid-state sensor in an operating condition. |
| Momentary Contact
| Contacts return from operated position to normal condition when actuating force is removed. |
| Non-ferrous
| A metallic material which does not contain steel, nickel or cobalt. |
| Normally Closed (NC)
| The condition of the contact when the circuit is not energized. Contacts are closed. |
| Normally Open (NO)
| The condition of the contact when the circuit is not energized. Contacts are open. |
| NPN (Current Sink)
| The sensor derives (“sinks”) its current from the load. |
| Operate Point
| The point at a distance from the sensor face at which a target is detected. |
| Operating Force
| Straight line force applied to the actuator, to cause the switch’s contacts to snap to the operated position. |
| Overtravel
| The movement of the actuator beyond the contact trip position without damage occurring to the switch. |
| Perfect Prox
| Two photodetectors of different sensing ranges are used to detect an object while ignoring a nearby background. |
| Polarized Reflex
| For the detection of shiny objects, these filters condition the light to prevent a false signal. |
| Positive Opening Contacts
| The separating of the normally closed (NC) contact is done with a non-spring device to ensure that a light contact weld situation can be broken. (A safety feature) |
| PNP (Current Source)
| The sensor provides (“sources”) the current to the load. |
| Pre-travel
| The distance or angle through which the actuator moves before reaching the point at which the contacts are tripped. |
| Programmable Output
| Sensor output functions that can be wired to output either normally open or normally closed, but not simultaneously. |
| Proximity Sensor
| A device used to detect the presence or absence of a metallic object using an electronic non-contact sensor. |
| Release Point
| The point where the target is beyond the detection range of the sensor. |
| Release Time
| Time delay between when a target reaches the release point and the output restores to the unoperated state. |
| Response Time
| Time interval from when the target reaches the operate point and the output goes into the operated state. |
| Retro-Reflective
| Mode of detection where the sensor bounces light off a reflector which is caught by the detector. |
| Return Force
| Amount of force still applied to a switch plunger or actuator at the moment the contacts snap from operated position to unoperated position. |
| Sensing Range
| The distance from a sensor to the target. |
| Shielded
| A standard range sensing coil. |
| Snubber Circuit
| Circuit composed of a resistor and a capacitor in series, and connected across the device. |
| Thru-Beam
| Mode of detection where the sensor light aims the beam directly at the detector. Most basic approach. |
| Unshielded
| An extended range coil. |
| Zero Crossing
| The point in an AC cycle when the sine wave is at zero. |
