Reed switches in Floor detection in Elevators and Lifts
Most people are aware of Elevators, or lifts, as they are called in certain countries of the world. They are used to transport people and goods between floors or decks, and are powered by electrical motors. These electrical motors, however well programmed to start and stop at the required floors, need feedback on the exact position of the elevator box to apply the final brakes. This is to ensure that there is less than inch level difference between the elevator floor and the actual level floor. This feedback is very accurately provided by latchingreed sensors that stay in an actuated state as an elevator passes floors on the way up and stay in an non-actuated state as the elevator passes floors on its way down. These Latching reed sensors are mounted on every floor and are changed state by the magnet on the elevator, as it moves up or down, past each sensor. The polarities of the magnet and the Reed Sensors can be matched differently, and the actuated states of the sensor can either be latched for floors above the elevator and non-latched for floors below the elevator, or vice versa. The latched and unlatched condition of the sensors can be compared to electronic flip flops with built in driver circuits, and have the added advantage of switching higher loads.
The construction and design of reed switches and selection of magnets for latching applications requires years of experience. We work very closely with our elevator OEMs to provide custom, cost-effective solutions and work backwards to provide the best contact coating specifications for reed switches, that make it very easy for users to build latching reed switches for such application using custom magnets.