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Resistance based process control device diagnostics

  • US 6,449,574 B1
  • Filed: 07/14/2000
  • Issued: 09/10/2002
  • Est. Priority Date: 11/07/1996
  • Status: Expired due to Term
First Claim
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1. A process control device in a process control system, comprising:

  • an electrical element having an electrical resistance;

    process control device circuitry coupled to the electrical element to perform a process control function;

    self heating circuitry coupled to the electrical element providing a self heating signal related to a self heating index (SHI) representing an amount of degradation of the electrical element due to the electrical resistance;

    circuitry coupled to a process control loop for coupling the device to the loop; and

    diagnostic circuitry coupled to the self heating circuitry responsively providing a diagnostic output related to health of the electrical element as a function of the self heating signal.

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