The resettable fuse consists of a PTC device - a positive temperature coefficient device. A higher-level controller or a switching device then disconnects the motor from the voltage supply. when the Bimetallic thermometers use: A. Thermal overload relays are installed in motor circuits and the current going to the motor passes through the bimetallic tripping element. A bimetallic switch is a switching element with contact, which opens the contact when the switching temperature is reached. 5 is typical of those used in ovens. • These breakers have a bimetallic element that carries current. An excessive amount of current will heat the element, causing the two metals to expand but at different expansion rates since they are selected for their different temperature coefficients (Figure 2). Their output also varies as the bimetallic element fatigues and as their internal contacts grow dirty.) The flowing current heats the bimetallic strip which causes the bimetallic material to bend, and after a specific temperature, the bimetallic strip will open the relay. The The device shown in Fig. US2897312A US664880A US66488057A US2897312A US 2897312 A US2897312 A US 2897312A US 664880 A US664880 A US 664880A US 66488057 A US66488057 A US 66488057A US 2897312 A US2897312 A US 2897312A Authority US United States Prior art keywords plate switch magnetic magnetostrictive permanent magnets Prior art date 1957-06-03 Legal status (The legal status is an … The bimetallic switch does not reengage immediately after tripping, e.g. The output bimetallic element is a pressure b voltage c mechanical strain d mechanical displacement Generally, it is a mechanical device where the mechanical action of this device can be used for activating the switching mechanisms to acquire electronic output. The element is then pulled to one side, thus breaking the connection. Construction of Bimetallic Thermometer. Transfer function of a system is defined as the ratio of output to input in: a) Z-transformer b) Fourier transform c) Laplace transform d) All of these. The output is the variable of the process that is being measured and compared to the input; in the above example, it is room temperature. Thus, when the temperature inside the oven drops below a certain point, the bimetallic strip bends upwards enough to complete the circuit, switching on the heating element. If no ground fault is present, no current imbalance is present; hence no current will flow in the protection circuit. The construction of this thermometer can be done using two bimetallic strips that are connected to form dissimilar thermal expansion coefficients. The output of the core-balance CT will be the difference or imbalance of current between the three phases. The sensing elements are the measuring devices used in the feedback loop to monitor the value of the output variable. 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