Temperature sensor transmitter with sensor sheath lead

A temperature transmitter in a process control loop, comprising:

• a sensor housing;
• temperature sensing means positioned within the temperature sensor housing for sensing a temperature and providing a sensor output related to the sensed temperature;
• an element lead coupled to the sensor output and extending from the sensor housing;
• a sheath lead coupled to the sensor housing and extending from the sensor housing;
• A/D converter means coupled to the element lead and the sheath lead for converting analog signals received on the element lead and the sheath lead into digital signals;
• microprocessor means coupled to the A/D converter for controlling operation of the A/D converter;
• and
• input-output means coupled to the microprocessor for sending and receiving information over the process control loop.

A temperature transmitter in a process control loop, comprising:

• a temperature sensor comprising:
• a sensor sheath;
• a sensor element positioned within the sensor sheath for providing a temperature signal representative of a temperature of the sensor element;
• an element lead coupled to the sensor element and extending from the sensor sheath;
• and
• a sheath lead coupled to the sensor sheath and extending from the sensor sheath;
• and
• a transmitter circuit comprising:
• temperature measurement means coupled to the element lead for generating a temperature measurement as a function of the temperature signal;
• an input-output circuit coupled to the temperature measurement means for communication with the process control loop;
• and
• insulation resistance measurement means coupled to the sheath lead for generating an insulation resistance measurement as a function of a resistance between the element lead and the sheath lead.