Advantages of Thermocouples Inexpensive
- No resistance Lead wire
Problems
- Fastest Response
- Simple and Rugged
- High
Temperature Operation
- Tip
(end) Temperature Sensing
|
Disadvantages of
Thermocouples
- Least Sensitive
- Non-linear
- Low
Voltage
- Least
Stable, Repeatable
|
Advantages of Resistance Temperature
- Detectors
- Linear over wide operating range
- Wide temperature operating range
- Interchangeability over wide range
- Good stability at high temperature
|
Disadvantages
of Resistance
- Temperature Detectors
- Low sensitivity
- Higher cost than thermocouples
- No point sensing
- Affected by shock and vibration
- Requires three or
four-wire operation
|
Summary
– Resistance Temperature Detector or Thermocouple
Both thermocouples and RTD’s
are useful sensors for determining process temperature. RTD’s
provide higher accuracy than thermocouples in their temperature range because
platinum is a more stable material than are most thermocouple materials. RTD’s also use standard instrumentation wire to connect
to the measurement or control equipment. Thermocouples are generally less expensive
than RTD’s, they are more durable in high vibration or mechanical
shock applications and are usable to higher temperatures. Thermocouples can
be made smaller in size than most RTD’s so they can
be formed to fit a particular application. |
