Signal Isolator 4 20ma
The AC-420-420 is an industrial precision active 4–20mA current loop isolator designed to break electrical ground loops, suppress common-mode noise, and protect sensitive PLC and DCS analog input channels. Built with a pure linear analog isolation amplifier without PWM conversion or digital reconstruction, it achieves an ultra-fast response time (< 1 ms) and exceptional signal fidelity (< ±0.1% output ripple). With an ultra-high galvanic isolation barrier of 4.25 kV RMS between input and output circuitry, it safely separates field instrumentation grounds from control room automation systems, preventing signal degradation, measurement ground drift, and equipment damage from hazardous industrial electrical faults.
Key Features
- 4–20mA input to 4–20mA output galvanic current loop isolation
- 4.25 kV RMS galvanic isolation between input and output
- 1.5 kV RMS isolation between input and auxiliary power
- Ultra-fast response time (< 1 ms) for dynamic process loops
- Drives loop loads up to 500 Ω with ±0.2% full-scale accuracy
- Pure analog linear amplifier topology with zero digital sampling delay
- Front-panel multi-turn Zero and Span calibration potentiometers
- 24V DC auxiliary power supply (18V to 30V DC operating range)
- Compact 22 mm DIN rail and wall mountable enclosure
- Dimensions: 100 mm × 76 mm × 22 mm
Ordering Information
| Product Code | Description |
|---|---|
| AC-420-420 | Signal Isolator 4–20mA to 4–20mA Current Loop Isolator (24V DC, 4.25kV Isolation) |
| AC-20mA-2 | Isolated 20mA Splitter (1 In, 2 Out) |
| AC-10V-10V | Isolated Analog Signal Converter 10V to 10V DC |
| SPD-20MA | 4–20mA Surge Protection Device |
| USS20M24V-D | Current Source Simulator 0/4 to 20mA with Digital Display |
| SPD-24V-DC | Surge Protection Device 24V DC SPD |
Applications
- Ground Loop Elimination: Resolves ground potential differences between remote field transmitters and central control systems.
- PLC & DCS Analog Input Protection: Protects expensive automation analog input channels from voltage spikes and fault currents.
- VFD & Motor Drive Feedback: Isolates speed, current, and torque 4–20mA feedback signals in high-EMI drive enclosures.
- Water & Wastewater Treatment: Isolates flowmeters, pH sensors, and level probes across distant pump stations.
- Chemical & Petrochemical Processing: Clean 4–20mA signal transmission between hazardous field areas and safe control rooms.
Specifications
| Parameter | Value |
|---|---|
| Mounting Type | 35 mm DIN Rail & Wall Mounting |
| Dimensions | 100 mm x 76 mm x 22 mm (L x H x W) |
| Weight | 100 g |
| Enclosure Material | Industrial Grade ABS |
| Operating Temperature | 0 °C to +50 °C (Industrial: -10 °C to +60 °C) |
| Storage Temperature | -40 °C to +85 °C |
| Relative Humidity | 5% to 95% RH (non-condensing) |
Electrical Specifications
| Parameter | Specification |
|---|---|
| Power Supply Voltage | 24V DC \(\pm 25\%\) (18V to 30V DC) |
| Operating Current | 100 mA @ 24V DC |
| Input Signal Range | 4.00 mA to 20.00 mA DC (operational: 0 to 22 mA) |
| Input Impedance | \(\le 100\,\Omega\) |
| Output Signal Range | 4.00 mA to 20.00 mA DC (Active Current Loop, Load \(\le 500\,\Omega\)) |
| Conversion Accuracy | \(\pm 0.2\%\) of Full Scale @ 25 °C (max \(\pm 0.5\%\)) |
| Output Ripple Noise | \(< \pm 0.1\%\) of Full Scale |
| Response Time | \(< 1\text{ ms}\) (< 1 milliSec) |
| Temperature Drift | \(< 100\text{ ppm} / \text{°C}\) |
| Status Indication | Power LED ON (PWR) |
| Field Calibration | Front-panel multi-turn Zero and Span trimpots |
Isolation & Protection Specifications
| Parameter | Value | Standard / Notes |
|---|---|---|
| Galvanic Isolation (Input to Output) | 4,250 V RMS (4.25 kV) | Optical & magnetic isolation barrier (1 min) |
| Galvanic Isolation (Input to Aux. Power) | 1,500 V RMS (1.5 kV) | Continuous dielectric isolation |
| Output to Aux. Supply | Shared Common Ground | Non-isolated reference ground |
| Reverse Polarity Protection | Integrated | Protects internal circuitry against reverse DC supply wiring |
| Transient Clamping | 600W TVS | Surge and spike suppression across all ports |
Functional Isolation Architecture & Dynamic Response
The pure linear analog architecture provides true continuous signal isolation without quantization stepping or switching ripples.
Oscilloscope Dynamic Waveform Verification
Oscilloscope measurement verifying that the isolated output signal reproduces the input waveform with sub-millisecond response latency (< 1 ms) and clean signal fidelity:
Mechanical Dimensions
Terminal Details & Wiring
Connection Pinouts
| Terminal Block | Pin | Label | Signal | Description |
|---|---|---|---|---|
| Input Terminals | 18 | 18 + | Input (+) | 4–20mA Current Loop Input (+) |
| (Bottom Block) | A2 | A2 - | Input (-) | 4–20mA Current Loop Return (-) |
| – | NC | Unused | Reserved / Not Connected | |
| – | NC | Unused | Reserved / Not Connected | |
| Output Terminals | 15 | 15 OP+ | Output (+) | Active 4–20mA Analog Output (+) |
| (Top Block) | 26 | 26 OP- | Output (-) | Analog Output Ground Return (-) |
| Power Terminals | A1 | A1 V+ | +24V DC | Auxiliary Power Supply Input (+24V DC) |
| (Top Block) | 25 | 25 GND | Power 0V | Auxiliary Power Supply Ground Return |
Available Variants & Configurations
The Veawe Precision Analog Isolator family is available in standardized and custom input/output configurations:
| Signal Converter Input | Output | High Voltage Input | Output | Transducer Input | Output |
|---|---|---|---|---|---|
| 0–20 mA | 0–20mA, 4–20mA, 0–10V, ±10V | 30V DC | 0–20mA, 4–20mA, 0–10V | Pt100 | 0–20mA, 4–20mA, 0–10V |
| 4–20 mA | 0–20mA, 4–20mA, 0–10V, ±10V | 70V DC | 0–20mA, 4–20mA, 0–10V | Pt1000 | 0–20mA, 4–20mA, 0–10V |
| 0–10 V DC | 0–20mA, 4–20mA, 0–10V, ±10V | 100V DC | 0–20mA, 4–20mA, 0–10V | K type | 0–20mA, 4–20mA, 0–10V |
| 0–5 V DC | 0–20mA, 4–20mA, 0–10V, ±10V | 150V DC | 0–20mA, 4–20mA, 0–10V | J type | 0–20mA, 4–20mA, 0–10V |
| 75 mV DC | 0–20mA, 4–20mA, 0–10V, ±10V | 300V / ±300V DC | 0–20mA, 4–20mA, 0–10V | Resistance | 0–20mA, 4–20mA, 0–10V |
| ±75 mV DC | 0–20mA, 4–20mA, 0–10V, ±10V | 350V DC | 0–20mA, 4–20mA, 0–10V | — | — |
| — | — | 100V AC | 0–20mA, 4–20mA, 0–10V | — | — |
| — | — | 5A AC (CT) | 0–20mA, 4–20mA, 0–10V | — | — |
LED Indications and Diagnostics
| LED | Color | Status | Description |
|---|---|---|---|
| PWR | Green | ON | Auxiliary 24V DC operating power connected and regulated |
Revision History
| Revision | Date | Description of Change |
|---|---|---|
| Rev 1.0 | 2026-09-09 | Initial datasheet release |
Get the latest version of this datasheet : click here..
Support
Website: www.veawe.io
Email: info@veawe.io