When switching inductive loads a high voltage spike

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Unformatted text preview: are suitable for accurate positioning tasks. With electro-mechanical position switches, maximum current must be restricted as this can otherwise lead to arc discharge during switching on and off and therefore burning out of the contacts. A series resistor serves as a current limiter thus prolonging the service life of the contacts. When switching inductive loads, a high voltage spike is created at the moment of cut-off. For this reason, a protective circuit must be provided for the position switch. 28 © Festo Didactic GmbH & Co. KG • FP 1110 2. Mechanical position switches The protective circuit can either be a suitable RC element or a corresponding diode or Varistor (see circuit diagram). The electrical values of these components depend on the following power component (e.g. relay, contactor etc.). If a relay or contactor is activated, it is essential that the technical data of the switch and the relay or contactor be observed. The pull-in power of a relay or contactor is several times higher (8- to 10-fold) than the holding power. Therefore it is important...
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This note was uploaded on 11/01/2012 for the course CHEMICAL 102 taught by Professor Jamesrodriguez during the Spring '12 term at Universidad Politécnica de Cartagena.

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