Load Cell Amplifier Module 0--20mA / 4-...
Load Cell Amplifier 4–20mA / 0–20mA AC-LD-20MA
The AC-LD-20MA (UC-LD-420mA) is an industrial strain gauge load cell signal conditioner engineered to convert low-level millivolt bridge outputs into an industry-standard 4–20mA (or 0–20mA) analog current signal. Featuring exceptional loop drive capability up to \(1.1\,\text{k}\Omega\), integrated sensor excitation, multi-turn Zero and Span field adjustment potentiometers, and an ultra-fast response time under 1 ms, it is ideally suited for long-distance signal transmission in harsh, electrically noisy industrial environments.
Key Features
- Full-bridge strain gauge load cell input (1 mV/V, 2 mV/V, 3 mV/V)
- Built-in precision regulated bridge excitation supply
- 4–20mA / 0–20mA active current output (< 0.5% ripple noise)
- High output drive capability powering loop impedances up to 1,100 Ω
- Ultra-fast response time (< 1 ms) for dynamic checkweighing systems
- Front-panel multi-turn Zero and Span calibration potentiometers
- Continuous output short-circuit and input reverse polarity protection
- ±15 kV ESD protection across all signal and power terminals
- 24V DC industrial power supply input (18V to 30V DC)
- 35 mm DIN rail and wall mountable housing
- Dimensions: 110 mm × 50 mm × 55 mm
Ordering Information
| Product Code | Description |
|---|---|
| AC-LD-20mA | Load Cell Amplifier 4–20mA / 0–20mA (1.1k \(\Omega\) Load, 24V DC, DIN Rail / Wall Mount) |
| AC-LD-10 | Load Cell Amplifier 0–10V (24V DC, DIN Rail / Wall Mount) |
| AC-LD-B10 | Bipolar Load Cell Amplifier ±10V (Bidirectional Tension/Compression) |
| MIO-1LD | Loadcell to Modbus RTU RS485 Transmitter |
| USS20M24V-D | Current Source Simulator 0/4 to 20mA with Display |
| SPD-20MA | 4-20mA Surge Protection Device |
Applications
- Vessel, Silo & Tank Weighing: Converting multi-cell load cell sum boxes into 4–20mA signals for PLC analog input modules.
- High-Speed Checkweighers & Bagging Machines: Real-time sub-millisecond weight measurement for high-throughput production lines.
- Industrial Belt Scales & Conveyors: Continuous bulk material flow monitoring over long factory cable runs.
- Web Tension & Roll Measurement: Transmitting load cell readings to tension controllers with high noise rejection.
- Crane & Hoist Overload Protection: Interfacing load pins and tension shackles directly to safety PLCs.
Specifications
| Parameter | Value |
|---|---|
| Mounting Type | 35 mm DIN Rail & Wall Mounting |
| Dimensions | 110 mm x 50 mm x 55 mm (L x W x H) |
| Weight | 100 g |
| Enclosure Material | Industrial Grade ABS |
| Operating Temperature | 0 °C to +85 °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 |
| Operating Current | 200 mA @ 24V DC |
| Sensor Input Type | Full-bridge strain gauge load cell with excitation source |
| Sensor Excitation Output | Integrated precision excitation supply (EX+, EX-) |
| Output Signal Range | 4.00 mA to 20.00 mA (configurable for 0 to 20 mA) |
| Maximum Output Load Resistance | \(1.1\,\text{k}\Omega\) (\(1,100\,\Omega\)) @ 24V DC |
| Accuracy | < \(\pm 1\%\) of Full Scale @ 25 °C ambient temperature |
| Output Ripple Noise | < 0.5% of Full Scale |
| Response Time | < 1 ms (< 1 milliSec) |
| Reverse Polarity Protection | Integrated diode on 24V DC input |
| ESD Protection | \(\pm 15\text{kV}\) Air / HBM, Contact discharge across all I/O pins |
Calibration Procedure
The front-panel multi-turn potentiometers enable quick and accurate field calibration:
- Zero Offset Calibration:
- Install the load cell sensor in its mechanical mount with no test weight applied (tare condition).
- Measure the output current between terminals
OUT +andOUT -using a calibrated multimeter in current mode. - Adjust the front ZERO potentiometer until the output current reads \(\approx 4.00\text{ mA}\) (or \(0.00\text{ mA}\) if configured for 0–20mA).
- Span Calibration:
- Place a known certified calibration weight (or apply full-scale reference force) onto the load cell.
- Measure the output current and adjust the front SPAN potentiometer until the output reads \(\approx 20.00\text{ mA}\) (or proportional to the applied load).
- Verification:
- Remove the load and verify that the output current returns cleanly to \(4.00\text{ mA}\). Repeat fine-tuning if necessary.
Mechanical Dimensions
Terminal Details & Port Pinouts
Loadcell Sensor & Power Connections
| Terminal Block | Pin | Label | Signal | Description |
|---|---|---|---|---|
| Loadcell Terminal | 1 | EX+ | Excitation (+) | Precision positive excitation voltage to load cell |
| (Top 5-Pin Block) | 2 | S+ | Signal (+) | Positive differential signal input from load cell |
| 3 | SLD | Shield | Cable shield connection (Earth ground) | |
| 4 | S- | Signal (-) | Negative differential signal input from load cell | |
| 5 | EX- | Excitation (-) | Negative excitation return to load cell | |
| DC Power | 1 | V+ | Power Input | +24V DC Operating Power Supply |
| (Bottom Left) | 2 | V- | Power Ground | 0V Power Ground Return |
| 4 to 20 mA Output | 1 | OUT + | Current Out (+) | Active 4–20mA / 0–20mA Current Output Signal |
| (Bottom Right) | 2 | OUT - | Current Out (-) | Current Return / Signal Ground |
LED Indications and Diagnostics
| LED | Color | Status | Description |
|---|---|---|---|
| PWR | Green | ON | Operating power connected and bridge excitation active |
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
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Email: info@veawe.io