4-20mA Two-Wire Passive Current Loop Signal Isolator Module

Device features:

1. Protect the control loop of the upper stage of the host computer.

2. Reduce the impact of environmental noise on the test circuit, and can overcome inverter noise and various high and low frequency pulsation interference.

3. It suppresses the interference of circulating currents in public ground wires and pulses of frequency converters, solenoid valves, thyristors, etc. to equipment. It also has the function of limiting voltage and current for lower-level equipment. It is a faithful protection for transmitters, instruments, frequency converters, solenoid valves, PLC/DCS input and output, and communication interfaces.

The DIN35 series standard 35mm guide rail card holder structure is easy to install and can effectively isolate: the potential difference between signal input, signal output, power supply and earth.

Product Advantage

ISO 4-20mA Series — Two-wire Passive 4-20mA Current Loop Signal Isolator

1.The ISO 4-20mA, ISOS 4-20mA, and ISOH 4-20mA series are two-wire, passive 4-20mA (0-20mA) current loop analog signal isolators independently developed by Shunyuan Technology. Utilizing patented magneto-electric coupling isolation technology, they eliminate the need for an external power supply; instead, they "harvest" microwatt-level energy directly from the 4-20mA signal loop to power internal isolation circuitry, enabling high-precision, highly linear signal transmission between industrial field sensors and systems such as PLCs and DCS. The series offers three isolation voltage ratings—1kV (ISOS), 3kV (ISO), and 10kV (ISOH)—to meet diverse safety requirements ranging from standard industrial control to high-voltage power monitoring. With three mounting options—ultra-compact SIP (Single In-line Package), DIN35 rail mounting, and PIM panel-mount—these products offer exceptional flexibility for system integration and adaptability across various application scenarios.

2.The ISO 4-20mA series operates with true two-wire passive topology — it draws operating power directly from the 4-20mA current loop itself using Sunyuan's patented high-efficiency loop power-stealing technology. No external auxiliary power supply is required, ever. This eliminates extra wiring, reduces cabinet space, and drastically simplifies field installation. The input equivalent resistance is extremely low, allowing an ultra-wide input voltage range of 8.5-32VDC. Simply insert the module in series into any existing 4-20mA loop, and it delivers isolated, high-precision signal transmission instantly — a genuine plug-and-play isolation solution.

3.Backed by Sunyuan's proprietary electromagnetic isolation coupling invention patent, the series achieves isolation voltages of 1KVDC (ISOS 4-20mA), 3KVDC (ISO 4-20mA), and 10KVDC (ISOH 4-20mA). The internal signal modulation-demodulation circuit pairs with precision magnetic coupling to block common-mode interference, ground loops, and transient surges — all without compromising the 4-20mA signal integrity. Whether protecting sensitive PLC analog input cards in a standard control cabinet or isolating high-voltage monitoring circuits in power substations, you choose the isolation grade that matches your safety requirements.

4.The module comes in ultra-compact SIP single-in-line IC packages — SIP7 (ISOS), SIP12 (ISO), and SIP16 (ISOH) — designed for direct PCB soldering inside instruments, transmitters, and controller boards. This replaces bulky discrete isolation circuitry, saving board real estate and BOM cost. For field deployment, the same core technology is available in DIN35 rail-mount housings (supporting 1-in-1-out, 2-in-2-out, and 3-in-3-out multi-channel configurations) and PIM panel-mount intelligent display transmitters with alarm control. One platform, every form factor.

5.Every module is built with ceramic substrate, printed resistor technology, and full encapsulation — delivering reliable operation across an industrial temperature range, high humidity, and sustained vibration. The design meets the rigorous demands of metallurgy, mining, petrochemical plants, and outdoor new energy installations. With over 7,900 product page views and continuous field deployment across industries, the ISO 4-20mA series has proven its robustness where it matters most — on the factory floor, not just on the datasheet.

Technical Parameters

Product Uses

Applications span metallurgy and mining (ore processing sensor isolation), petrochemical (hazardous-area signal conditioning), power generation and distribution (substation monitoring), medical devices (patient-connected safety isolation barriers), industrial robotics, new energy systems, and defense research. Wherever 4-20mA analog signals need galvanic isolation without adding power infrastructure, ISO 4-20mA series has a proven deployment record — from standard factory automation to mission-critical nuclear safety instrumentation.

Product Operate Guide

ISO 4-20mA.pdf