Isolated Analog Signal Converter ±75mV ...
The AC-B75MV-420 is an industrial precision bidirectional millivolt signal conditioner designed to convert the ±75mV DC drop across bidirectional current shunts into a standardized 4–20mA active current loop signal (with 12.00 mA representing 0 mV zero current). 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 a robust 4.25 kV RMS galvanic isolation barrier between high-current DC shunts and sensitive control circuitry, it eliminates hazardous ground loops and floating common-mode voltages, enabling safe bidirectional current monitoring for battery charge/discharge cycles, four-quadrant DC drives, and solar hybrid energy systems.
Key Features
- ±75mV DC bipolar shunt input to 4–20mA output (12 mA center-zero)
- 4.25 kV RMS galvanic isolation between shunt input and output
- 1.5 kV RMS isolation between input and auxiliary power
- Ultra-fast response time (< 1 ms) for bidirectional current monitoring
- Low output ripple noise (< ±0.1%) with ±0.2% full-scale accuracy
- Pure analog linear amplifier topology with zero digital sampling artifacts
- 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-B75mV-420 | Isolated Bipolar Shunt Converter ±75mV DC to 4–20mA (24V DC, 4.25kV Isolation) |
| AC-75mV-420 | Isolated Shunt Converter 0–75mV DC to 4–20mA |
| AC-420-420 | Signal Isolator 4–20mA to 4–20mA Current Loop Isolator |
| 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
- Battery Charge/Discharge Monitoring: Accurately tracks net ampere-hours and power flow in solar storage, telecom battery banks, and UPS systems.
- Four-Quadrant DC Motor Drives: Measures forward, reverse, and regenerative braking currents in heavy industrial drives and hoists.
- Electrolyzer & Plating Polarity Monitoring: Tracks current direction and magnitude in reversible electrochemical and plating operations.
- SCADA & PLC Integration: Safely provides bidirectional DC current data to standard single-ended analog PLC inputs without requiring bipolar input cards.
- Control Panel Building: Compact 35 mm DIN rail mounting for clean and space-efficient cabinet wiring.
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 | -75.0 mV to +75.0 mV DC (±75mV DC Bipolar Shunt Drop) |
| Input Impedance | \(> 100\,\text{k}\Omega\) |
| Output Signal Range | 4.00 mA to 20.00 mA (12.00 mA @ 0 mV, 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 + | Shunt (+) | ±75mV DC Shunt Lead (+) |
| (Bottom Block) | A2 | A2 - | Shunt (-) | ±75mV DC Shunt Lead (-) |
| – | 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