Galvanically isolated signal conversion vs. shunt resistor conversion
In industrial automation, reliable signal conversion is essential for safe processes and smooth operation. Two approaches are in focus: galvanically isolated signal conversion and shunt resistor conversion.
autosen consistently relies on galvanic isolation and offers powerful solutions with the devices AN101 (signal splitter) and AN103 (power supply isolator).
Galvanically isolated signal conversion
How it works: Input, output and supply are electrically isolated from each other. Signal transmission takes place via optocouplers, transformers or capacitive coupling. This reliably prevents interference, earth loops and potential differences.
Product features:
- AN101 signal splitter: 4-port isolation, 2 outputs, integrated auxiliary power 16 V/35 mA, signal ranges 4…20 mA, 0…10 V etc., accuracy < ± 0.1 %, cut-off frequency 5 kHz, 6.2 mm housing width.
- AN103 power supply isolator: 3-port isolation, supply for 2-/3-/4-wire transmitters, configuration via DIP switch, accuracy < ± 0.1 %, response time 150 µs, also compact at 6.2 mm.
Advantages:
- Maximum immunity to interference
- Very high accuracy
- Flexible signal processing (current and voltage signals, redundant outputs)
- Robust industrial quality in a compact design
Galvanically isolated signal conversion
How it works: A current signal (e.g. 4–20 mA) is converted into a voltage signal (e.g. 0–10 V) via a resistor.
Limitations:
- No galvanic isolation → risk of interference and earth loops
- Accuracy depends on resistor tolerance and temperature
- Only current → voltage possible, no reverse conversion voltage → current
- Not robust enough for harsh industrial environments
Galvanically isolated vs. shunt resistor conversion in a direct comparison
| Criterion | Galvanically isolated (AN101 / AN103) | Shunt resistor conversion |
|---|---|---|
| Electrical isolation | Complete (3-/4-port isolation) | Not available |
| Signal ranges | Flexible for current and voltage signals | Current → voltage only |
| Accuracy | < ± 0.1 % (temperature-stable) | Medium to low (tolerance-dependent) |
| Response time / frequency | up to 150 µs / 5 kHz | severely limited |
| Auxiliary power | 16 V DC, 35 mA for 2-wire sensors | Not available |
| Design | 6.2 mm DIN rail, very compact | Depends on the set-up, larger |
| Industrial use | Standard in robust applications | More for basic applications |
Conclusion:
Shunt resistor conversion is technically simple and cost-effective, but it quickly reaches its limits in industrial applications: no galvanic isolation, limited accuracy and lack of flexibility.
By contrast, autosen’s galvanically isolated solutions – AN101 and AN103 – guarantee precise, interference-free and flexible signal processing in a compact design, making them the right choice for demanding industrial environments.
