What is a Signal Isolator?
Signal isolator is a kind of factory automation equipment that blocks the interference path through galvanic isolation technology, and its main function is to isolate the input and output signals to prevent interference between different circuits (such as ground loop, electromagnetic noise, etc.), and at the same time convert the input signal into a stable and isolated output signal to ensure the accuracy of data transmission and system security
Why 90% of factories can't do without signal isolators?
I'm going to explain three reasons why factories need signal isolators.
Block ground loop interference
In long-distance cable transmissions, the difference in ground potential between different devices can generate interference voltages of up to tens of volts. Signal isolators eliminate such noise by passing through an isolation barrier of 2500V DC, such as the Phoenix MINI MCR series.
Improve system security
In hazardous environments such as petrochemical industries, isolators protect PLC/DCS systems from high-voltage surges or lightning strikes (IEC 61000-4-5 compliant).
Signal lossless conversion
It supports 4-20mA↔0-10V, thermocouple ↔RTD and other cross-protocol conversions, solving the compatibility problems of new and old devices (such as OMRON K3HB-XVD series).
What are the types of signal isolators?
Signal isolators can be divided into many types according to the power supply method, wiring method and functional design, and I will introduce the types of signal isolators in detail according to these three methods.
Classified according to the mode of power supply
1)Passive signal isolator: does not require an external power supply, and is driven by its own energy through the input signal, which is suitable for simple, low-power scenarios (such as the CE-SZ17-50MS1 model).
2)Active signal isolator: It needs to be powered by an external power supply, supports signal amplification and complex processing, and is suitable for high-speed and long-distance transmission (such as Accuray BM100).
Classified according to wiring mode
1)Two-wire system: only power line and signal line are required, with low cost but single function.
2)Three-wire/four-wire: Independent power cord and multi-signal channel design improve stability and anti-interference ability, suitable for multi-device collaboration scenarios.
Special function models
1)USB isolator (e.g. USB-ISO): used to isolate computer USB ports from industrial equipment to prevent ground loop interference, with isolation voltages up to 2.5kV AC.
2)Multi-channel isolators (e.g., MTL4600): support analog inputs, outputs, and digital signal processing, suitable for complex industrial control systems.
How to choose a signal isolator that fits your needs?
Choosing a signal isolator is a complicated issue, but as a signal isolator supplier, our team of engineers has their own set of selection methods, and I will now share it with you.
Isolation technology selection:
Optocoupler isolation: low-cost, suitable for low-frequency signals (<1kHz), but low withstand voltage (≤3kV).
Magnetically Coupler Isolation: High-speed transmission (up to 150Mbps), strong anti-interference, suitable for inverter scenarios (such as ADI ADuM series).
Electromagnetic isolation: withstand voltage up to 5kV (such as PULS CT series), suitable for high-risk environments such as power systems.
Signal Type Matching:
Analog signal: 4-20mA/0-10V requires an isolator with HART protocol (e.g., MTL5041).
Digital signals: RS-485/CAN bus isolation requires built-in surge protection (e.g. TI ISO3082).
Environmental Adaptability:
High temperature workshop: choose an industrial-grade model with an operating temperature of -40°C~85°C (such as WAGO 857-645).
Wet environment: IP67 protection class + coated PCB design (e.g. Phoenix 2903275).
If you need various of Signal isolator and other factory automation parts, feel free to contact us. We are a professional factory automation parts supplier in China with many years of experience.