What Is a Current Sensor?
A current sensor is a sensor that measures the current flowing through a circuit. It uses two basic methods: shunt resistor and Hall effect.
Two Basic Methods
| Method | How | Isolation |
|---|---|---|
| Shunt resistor | Voltage across a resistor | None |
| Hall effect | The current's magnetic field | Yes |
Why Does Isolation Matter?
The shunt method connects in series with the circuit (no isolation); the Hall method measures without touching the current, i.e. it provides electrical isolation. At high voltage/current, Hall is safer.
Where Is It Used?
Energy/power monitoring, battery management systems, motor-drive protection, overcurrent detection and smart plugs/meters.
Is AC or DC Being Measured?
The shunt method measures both AC and DC but provides no isolation. Hall sensors also measure AC/DC and are isolated. To measure just the magnitude of AC current, a current transformer (CT) can also be used; it too is contactless and isolated.
Common Mistakes
- Forgetting power loss in the shunt: a shunt heats up at high current.
- Ignoring Hall offset: there's a small output even at zero current; it must be calibrated.
- Wrong range: a sensor suited to the max current you'll measure must be chosen.
Frequently Asked Questions
What is the ACS712?+
Shunt or Hall?+
Search parts related to "What Is a Current Sensor?"
Find the right part by comparing price, stock and distributors.