A temperature transmitter converts the signal from a Pt100, type K, S or other sensor into a standard 2-wire 4–20 mA signal that is noise-immune and can travel long distances to the PLC or DCS. Head-mounted versions are compact and powered from the current loop. ISE supplies temperature transmitters following European practice (EN 60770, EN 61326-1, NAMUR NE43).
Temperature transmitter specifications
| Parameter | Value |
|---|---|
| Input | Pt100, Pt1000, thermocouple K, S, J, N… |
| Supply | 7.5 – 45 VDC |
| Output | 4–20 mA |
| Connection | 2-wire (shared power and signal) |
| Mounting | Head-mounted or DIN rail |
| Options | HART, isolation, Ex ia, NAMUR NE43 fault signalling |
How a 4–20 mA temperature transmitter works
- 2-wire loop: DC power and signal share one pair, reducing wiring cost.
- Linearisation: I = 4 + 16·(T − Tmin)/(Tmax − Tmin). For 0 – 200 °C, 100 °C gives 12 mA.
- NAMUR NE43: measuring range 4 – 20 mA, saturation 3.8 / 20.5 mA; sensor fault ≤ 3.6 mA or ≥ 21 mA.
- Load resistance: R ≤ (U − 7.5 V) / 22 mA – about 750 Ω at 24 V.
Why use a temperature transmitter?
- No lead-resistance error as with 2-wire Pt100.
- No costly extension cable for long thermocouple runs.
- Good noise immunity over hundreds of metres; standardised PLC inputs.
Reference standards
| Standard | Scope |
|---|---|
| EN 60770 | Evaluation of transmitters for industrial process control |
| EN 61326-1 | EMC of measurement and control equipment |
| NAMUR NE43 | 4–20 mA failure signal levels |
| NAMUR NE21 | EMC requirements for process equipment |
| EN 60751 / EN 60584-1 | Pt100 / thermocouple inputs |
Related products
Contact ISE
EQUIPMENT INDUSTRIAL SOLUTION CO., LTD (ISE) – Ho Chi Minh City, Vietnam.
Contact us: Sales +84 909 617 185 – Technical +84 979 117 185 – Email: [email protected]
