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A door operator may use sensors to prevent the door from coming into contact with a user. Full Energy operators require at least 3 sensors. Low-energy operators are not required to have safety sensors, as the door is allowed to come in contact with a user, given that the kinetic energy of the moving door is limited by the reduced moving speed.
Reed switches actuated by magnets are commonly used in mechanical systems as proximity sensors. Examples are door and window sensors in burglar alarm systems and tamperproofing methods. Reed switches have been used in laptops to put the laptop into sleep/hibernation mode when the lid is closed.
The simplest sensor consists of a light beam aimed across the opening: when the beam is broken by an obstacle, the operator prevents the door from closing. Infrared and radar safety sensors are also commonly used. Other sensors such as resistance-sensing motors can be used to reverse the closing action of the door after an obstacle is encountered.
Relay contacts 87 common contact 30/51 87a normally closed contact 87b normally open contact 88 common contact 2 30/51 (relay) 88a normally closed contact 2 88b normally open contact 2 Additional 52 signal from trailer 54g magnetic valves for trailer brakes 75 radio, cigarette lighter R 77 door valves control
Remote photoelectric sensors used for remote sensing contain only the optical components of a sensor. The circuitry for power input, amplification, and output switching is located elsewhere, typically in a control panel. This allows the sensor, itself, to be very small. Also, the controls for the sensor are more accessible, since they may be ...
A quick demonstration of an electronic door lock. An electronic lock (or electric lock) is a locking device which operates by means of electric current. Electric locks are sometimes stand-alone with an electronic control assembly mounted directly to the lock.
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Contacts may be operated by humans in push-buttons and switches, by mechanical pressure in sensors or machine cams, and electromechanically in relays. The surfaces where contacts touch are usually composed of metals such as silver or gold alloys [3] [4] that have high electrical conductivity, wear resistance, oxidation resistance and other ...