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By means of a light intensity sensor ( photoresistor, photodiode, phototransistor, etc.) that detects the amount of light that illuminates an environment, it triggers an electrical circuit that opens or closes the contacts of a mechanical relay or of a solid state relay. (power transistor, thyristor, triac, etc.), which activates the lighting ...
Three photoresistors with scale in mm Large CdS photocell from a street light. A photoresistor is less light-sensitive than a photodiode or a phototransistor.The latter two components are true semiconductor devices, while a photoresistor is a passive component that does not have a PN-junction.
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 ...
A photocell placed outside a building can sense darkness, and the time of day, and modulate lights in outer offices and the parking lot. Lighting is also a good candidate for demand response , with many control systems providing the ability to dim (or turn off) lights to take advantage of DR incentives and savings.
Motor control centers are usually used for low voltage three-phase alternating current motors from 208 V to 600 V. Medium-voltage motor control centers are made for large motors running at 2300 V to around 15000 V, using vacuum contactors for switching and with separate compartments for power switching and control.
The opening weeks of the NBA season have been besieged by absent stars. This past week’s games turned out to be particularly destructive. First, on Thursday, news broke that Philadelphia 76ers ...
Typical contact elements of an electromechanical relay or contactor. A “contact” is a pair of electrodes (typically, one moving; one stationary) designed to control electricity. Electromechanical switches, relays, and contactors “turn power on” when the moving electrode makes contact with the stationary electrode to carry current.
In light of middle-aged smokers reporting a higher likelihood of memory loss than nonsmokers, a 2022 study published in the Journal of Alzheimer’s Disease found that smoking cessation from 45 to ...