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Unlike a thermal fuse, a thermal switch is usually reusable and is therefore suited to protecting against temporary situations which are common and user-correctable. Thermal switches are used in power supplies in case of overload, and also as thermostats, and overheat protection in some heating and cooling systems. They are found in virtually ...
In electrical engineering, a limit switch is a switch operated by the motion of a machine part or the presence of an object. A limit switch can be used for controlling machinery as part of a control system , as a safety interlock , or as a counter enumerating objects passing a point.
The Uniform Mechanical Code (UMC) is a model code developed by the International Association of Plumbing and Mechanical Officials to govern the installation, inspection and maintenance of HVAC (heating, ventilating and air-conditioning) and refrigeration systems. It is designated as an American National Standard.
A Single-Pole, Single-Throw (SPST) mercury switch on millimetre graph paper, device length approximately 1.5 cm Another mercury switch design. A mercury switch is an electrical switch that opens and closes a circuit when a small amount of the liquid metal mercury connects metal electrodes to close the circuit. There are several different basic ...
A non-rechargeable battery always powers the thermostat. To limit the amount of power drawn from the battery, such thermostats use an impulse relay that does not require the continuous application of power to the relay's coil. These thermostats can be used on millivolt circuits, as well as conventional 24 VAC circuits.
The infinite switch itself was described in a 1975 patent of George F. Esker Jr. and Otto J. Cousins of the Harper Wyman Company. This switch would reset itself as the bi-metallic strip cooled, provided a cycle of calibrated opening and closing. It also provided an indicator light that remained on as long as the knob was not in the closed position.
A reference designator unambiguously identifies the location of a component within an electrical schematic or on a printed circuit board.The reference designator usually consists of one or two letters followed by a number, e.g. C3, D1, R4, U15.
The control circuit in a household HVAC installation. The wires connecting to the blue terminal block on the upper-right of the board lead to the thermostat. The fan enclosure is directly behind the board, and the filters can be seen at the top. The safety interlock switch is at the bottom left.