The Velleman VMA323 is a current sensor module based on the Allegro ACS712, designed for economical and precise AC or DC current sensing in various systems, including industrial, commercial, and communications. Its compact design allows for easy integration into existing setups.
Function Description
The core function of the VMA323 module is to measure current. It utilizes the Hall effect principle to detect the magnetic field generated by current flowing through an integrated conductor, converting this into a proportional analog voltage output. This analog output can then be read by a microcontroller, such as an Arduino, to determine the measured current. The module is particularly useful for applications requiring current monitoring, such as motor control, load detection and management, switched-mode power supplies, and overcurrent fault protection. It provides a non-invasive way to measure current, as the current path is isolated from the sensor's output circuitry.
Important Technical Specifications
- Model: VMA323
- Sensor Type: Current Sensor ACS712 Module
- Measurement Range: -20 A to +20 A (DC)
- Supply Voltage: 5 VDC
- Output Voltage (at no load): VCC/2 (which is 2.5V for a 5V supply)
- Scale Factor: 100 mV per A
- Dimensions: 31 x 13 x 12 mm
- Connectivity: Features a 3-pin header for VCC, GND, and Analog Output, and a 2-pin screw terminal for the current path.
The module's output voltage changes linearly with the measured current. For instance, with a 5V supply and a 100 mV/A scale factor, a current of +10A would result in an output of 2.5V + (10A * 0.1V/A) = 3.5V, while a current of -10A would result in 2.5V - (10A * 0.1V/A) = 1.5V. The no-load output of VCC/2 (2.5V) serves as the zero-current reference point.
Usage Features
The VMA323 module is designed for ease of use, particularly with prototyping platforms like Arduino.
- Simple Integration: The module's small size and clear pinout (load positive, VCC - 5V, load negative, ground, analogue output) facilitate straightforward connection to microcontrollers and power supplies.
- Arduino Compatibility: The provided example code demonstrates how to interface the VMA323 with an Arduino UNO. It involves reading the analog output from the sensor, converting it into a voltage, and then calculating the current in Amperes using the module's scale factor and offset.
- Analog Output: The sensor provides an analog voltage output, which can be directly connected to an analog input pin of a microcontroller. This allows for continuous monitoring of current.
- DC Current Measurement: While the ACS712 chip can measure AC, the VMA323 module is specified for DC current measurement in the -20A to +20A range.
- Overcurrent Protection: The module can be used as part of a system for overcurrent fault protection, allowing users to detect and react to excessive current draw.
- Illustrative Example: The manual includes a detailed example setup with a computer, Arduino UNO, potentiometer, DC power supply, ACS712 module, and a step-down constant current/voltage power supply. This example clarifies the wiring and provides a functional Arduino sketch for current measurement. The sketch demonstrates how to read raw analog values, convert them to voltage, and then calculate the current in Amperes, displaying the results via serial communication.
Maintenance Features
The VMA323 module is a solid-state electronic component and generally requires minimal maintenance.
- Indoor Use: The device is intended for indoor use only and should be kept away from rain, moisture, splashing, and dripping liquids to prevent damage.
- Temperature Considerations: Avoid switching on the device immediately after it has been exposed to changes in temperature. Allow it to reach room temperature to prevent potential damage.
- No User Modifications: All modifications to the device are forbidden for safety reasons and will void the warranty. Users should not attempt to alter the module's circuitry.
- Proper Handling: Damage caused by improper handling, negligent maintenance, abusive use, or use contrary to the manufacturer's instructions is not covered by the warranty. Users should ensure the module is handled carefully and connected correctly according to the manual.
- Environmental Disposal: At the end of its lifecycle, the device should not be disposed of as unsorted municipal waste. It must be taken to a specialized company for recycling or returned to the distributor or a local recycling service, adhering to local environmental rules.
- Cleaning: Cleaning and user maintenance should not be performed by children without supervision. For general cleaning, it is advisable to use a dry, soft cloth and avoid any liquids that could seep into the electronics.
- Warranty: Velleman offers a 24-month warranty on production flaws and defective material for consumer products. However, this warranty does not cover damage from oxidation, shocks, falls, dust, dirt, humidity, fire, water damage, lightning, accidents, natural disasters, deliberate or negligent misuse, or unauthorized repairs.
In summary, the VMA323 is a robust and easy-to-implement current sensor module for various DC current monitoring applications, emphasizing safe operation and proper environmental disposal.
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