Current Sensor (Hall / Shunt / CT)
Sensor
Devices that measure electric current by detecting magnetic fields (Hall/CT) or voltage drop across a known resistance (shunt). Essential for power monitoring and control.
What it looks like
Current Sensor (Hall / Shunt / CT)
A typical sensor — exact shape, colour and markings vary between manufacturers.
Types & variants
Key specs
Current range
AMin and max current the sensor can measure accurately. Must exceed expected operating range.
Accuracy
%How close the reading is to the actual current. Hall sensors typically ±1-3%, shunt ±0.1-1%.
Isolation voltage
VMax voltage between input and output circuits. Critical for safety in high voltage applications.
Output type
V/A/HzHall sensors often analog voltage, CTs produce current, some output digital signals.
Burden voltage
mVVoltage drop across shunt resistors. Higher drop = more power loss but better signal.
Markings
Hall sensors: Often have model numbers or current rating (e.g., '20A'). Shunts: Marked with resistance value (e.g., '100mΩ'). CTs: Ratio (e.g., '1000:5').
Standard values
Hall sensors: 5A to 100A ranges. Shunts: Common values 50mΩ, 100mΩ, 500mΩ. CTs: Standard ratios 1000:5, 2000:5, 5000:5.
How to choose
1) Determine max current and required accuracy. 2) Choose type: Hall for non-invasive, shunt for precision, CT for AC. 3) Check isolation for safety. 4) Verify output matches your system (ADC, microcontroller).
Pinout & package
Hall sensors: 3-pin (VCC, GND, OUT) or 2-wire (power/signal). Shunts: 2 large terminals. CTs: 2-wire secondary + ground. Packages: Module (Hall), through-hole (shunt), clamp-on (CT).
Example circuits
- Battery management system (BMS) monitoring
- Motor control and protection
- Energy monitoring in homes/buildings
- DC load control with microcontroller
- AC power quality measurement
Common failures
Hall sensors: Magnetic core saturation, thermal drift. Shunts: Overheating/burnout, value drift. CTs: Open circuit, insulation failure. Signs: Inaccurate readings, physical damage, overheating.
How to test
Hall sensor: Apply known current, measure output voltage with multimeter. Shunt: Measure voltage drop across terminals, calculate current (I=V/R). CT: Use known primary current, check secondary output.
Substitutes
Hall sensors can be replaced with other types if output is compatible. Shunts: Use same resistance rating or calculate equivalent parallel/series. CTs: Use same ratio but verify burden requirements.