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Rate-of-Rise (ROR) heat detectors operate on a rapid rise in element temperature of 6.7 to 8.3°C (12.1 to 14.9°F) increase per minute, irrespective of the starting temperature. This type of heat detector can operate at a lower temperature fire condition than would be possible if the threshold were fixed.
A thermal switch (sometimes thermal reset or thermal cutout (TCO)) is a device which normally opens at a high temperature (often with a faint "plink" sound) and re-closes when the temperature drops. The thermal switch may be a bimetallic strip, often encased in a tubular glass bulb to protect it from dust or short circuit. Another common design ...
These first circuits served as interconnects in cardiac pacemakers. Temperature instruments (transmitters, meters, controllers, and alarms) were also added in the 1970s. Recent products include optically-clear heaters, HDI and rigid-flex circuits, isolated temperature transmitters, and high temperature RTD elements.
These elements work with temperatures to 300 °C (572 °F) without further packaging, but can operate up to 600 °C (1,112 °F) when suitably encapsulated in glass or ceramic. Special high-temperature RTD elements can be used up to 900 °C (1,652 °F) with the right encapsulation. Wire-wound PRT. Wire-wound elements
Distributed temperature sensing systems (DTS) are optoelectronic devices which measure temperatures by means of optical fibres functioning as linear sensors. Temperatures are recorded along the optical sensor cable, thus not at points, but as a continuous profile. A high accuracy of temperature determination is achieved over great distances.
Maxim MAX704: Microprocessor Supervisory Circuit with Battery Backup. Supervisory circuits are electronic circuits that monitor one or more parameters of systems such as power supplies and microprocessors which must be maintained within certain limits, and take appropriate action if a parameter goes out of bounds, creating an unacceptable or dangerous situation.
In the case of a fire alarm, 6 mA could be normal, 15 mA could mean a fire has been detected, and 0 mA would produce a trouble indication, telling the monitoring site the alarm circuit had failed. Some devices, such as two-way radio remote control consoles, can reverse the polarity of currents and can multiplex audio onto a DC current.
A resettable fuse or polymeric positive temperature coefficient device (PPTC) is a passive electronic component used to protect against overcurrent faults in electronic circuits. The device is also known as a multifuse or polyfuse or polyswitch .