RTD Sensors versus TC Series
Characteristic | Thermocouple (T/C) | Resistance Temperature Detector (RTD) |
Measurement Range | Wide, -250°C to +2600°C | Narrower, -200°C to +850°C, often limited to a lower temperature by its insulation. |
Output Signal | Voltage wrt difference in end-to-end temperature |
Resistance change wrt actual temperature |
Accuracy | Less accurate, 2-4°C typical | More accurate, up to 1°C typical |
Long Term Stability | Fair, limited to shorter periods | Good, stable over long periods |
Stability/Drift | Good, but more subject to drift | Excellent, better long-term stability |
Sensitivity | Lower | Higher sensitivity |
Interchangeability | Good | Excellent |
Linearity | Fair linearity, special linearization generally required. |
Better linearity, special linearization still required, but to a lesser degree |
Self-Heating Error | No self-heating error | Some self-heating error, but low |
Extension Cable | High effect, must match T/C type and is more expensive |
Lower effect, can use different material, but ultimately limited by lead wire resistance |
Response Time | Fast (≤ 0.1 seconds typical), but CJC has thermal lag |
Slower (1 to 7 seconds typical) |
Repeatability | Reasonable | Better & greater standardization |
Hysteresis | Excellent | Good |
Signal Strength | Low, prone to EMI | Higher, more EMI resistant |
Vibration/Shock Resistance | Good resistance | Less resistant than T/C |
Robustness/Ruggedness | Very good | Good |
Sensor Dimensions | Very small to very large | Small to medium |
Measurement Area | Small, single point-of-contact | Larger, whole element must contact, 1” typical |
Fine Wire Diameter | Small down to 0.25mm diameter | Larger up to 3mm diameter |
Reference Junction | Required and a significant source of measurement error. Usually requires a stable ambient at cold junction. |
Not required and not a source of error |
Excitation Required | Not required, self-powered | Yes, reference voltage or current source |
Lead-Wire Resistance | High, but often mitigated by mating technology |
Must be considered wrt maximum added resistance and potential resistive imbalance between leads |
Cost | Less expensive | More expensive |
Complexity | Very simple and less subject to mechanical stress |
Physically larger and has a more complex construction making it more subject to mechanical stress |
Calibration Ease | More difficult and adds CJC calibration |
Less difficult, no CJC to contend with |
Noise Immunity | Lower noise immunity but often mitigated by good wiring practice. Small signals and high impedance leads can easily pick up noise. |
Better noise immunity than a T/C |
Nordson compatible heated hose are using both sensors as follows;
Nordson® RTD Series Heated Hoses | Nordson® TC Series Heated Hoses | |
Maximum Operating Temperature (°C ) |
232°C | 232°C |
Maximum Hydraulic Pressure (psi) |
1000 psi | 1500 psi |
Electrical Service | 120 VAC, 200 VAC, 240 VAC | 200 VAC, 230 VAC |
Avaliable Lenghts | up to 20 meter | up to 13 meter |
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