Welcome to NewproductsTuesday!!! This week, we are excited to have three different current sensor modules in our Grove ecosystem. They are the Grove – 2.5A DC Current Sensor(ACS70331), Grove – ±5A DC/AC Current Sensor (ACS70331) and the Grove – 10A Current Sensor (ACS725) . We will guide you further about current sensors and the differences between those in this post.
So, what is a current sensor?
A current sensor is a device that detects electric current in a wire, and converts current to a voltage that can be easily measured. Also, this will be proportional to the current through the measured path.
Current sensors are usually designed after taking two phenomena into consideration.
When a current is flowing through a wire,
- a voltage drop occurs
- a magnetic field is generated
Therefore, based on this, there are two types of current sensing,
- Direct sensing
- Indirect sensing
Direct sensing is based on Ohm’s law and Indirect sensing is based on Ampere’s Law.
Ohm’s law states that the current through a conductor between two points is directly proportional to the voltage across those two points.
Therefore, in direct sensing, the voltage drop is measured which is associated with the current passing through passive electrical components.
Faraday’s Law relates the rate of change of magnetic flux through a loop to the magnitude of the electro-motive force induced in the loop.
Ampere’s Law relates the integrated magnetic field around a closed loop to the electric current passing through the loop.
Therefore, indirect sensing involves the measurement of the magnetic field surrounding a conductor through which current passes.
Generated magnetic field is then used to induce
So, what’s the difference between these sensor modules?
Well, all these modules are based on the indirect sensing method, but what’s different is the theory of operation.
The Grove – 10A DC Current Sensor (ACS725) is a hall sensor whereas the Grove – 2.5A DC Current Sensor(ACS70331) and the Grove – ±5A DC/AC Current Sensor (ACS70331) are based on GMR (giant magneto-resistive) elements.
Hall effect is the production of a potential difference across an electrical conductor when a magnetic field is applied in a direction perpendicular to that of the flow of current. Therefore, the AC current is calculated by measuring the voltage drop across the resistor.
On the other hand, GMR (giant magneto-resistive) elements are resistors that change resistance with the applied field and calculate current according to that. These elements function differently than the Hall-effect sensors because the applied magnetic field is parallel to the surface of the sensor rather than perpendicular to the sensor plane as with Hall sensors. The main advantage of GMR is that it is around 25 times more sensitive than Hall-effect sensors, making it suitable for measuring small currents.
So, let’s have a look at the three sensors that we released. All these sensor modules are based on sensors by Allegro and here is a table of the comparison between them.
Please be careful when using these sensor modules, because if you come in contact with these modules, there is a danger of getting an electric shock.
Here are pinout diagrams of these sensor modules.
So guys, that is it for this week’s products release. Hope you guys like our new Grove current sensor modules!!! Stay tuned for more that are going to release next week!