When designing current measurement circuits, engineers often choose between Hall effect sensors and current transformers (CTs). Both measure current galvanically isolated from the circuit, but they have fundamentally different capabilities, limitations and cost profiles.
This guide compares Hall effect sensors and current transformers across key parameters, and helps you decide which technology fits your application.
Shaanxi SiRui Technology Co., Ltd. manufactures both current transformers and Hall-effect current sensors. Contact: sales@sirui-tech.com | Web: www.sirui-tech.com
1. How Each Works
Current Transformer (CT): uses magnetic induction—primary current creates a field in the core, inducing proportional secondary current. AC only, passive operation.
Hall Effect Sensor: uses the Hall effect—a Hall element in the core gap measures the magnetic field. Output voltage proportional to current. Measures both DC and AC, requires power supply.
2. Side-by-Side Comparison
| Parameter | Current Transformer | Hall Effect Sensor |
|---|---|---|
| Measures DC | No (AC only) | Yes (DC + AC) |
| Bandwidth | 50 Hz–20 kHz | DC–100 kHz |
| Accuracy | Class 0.1–1 (excellent) | Class 1–3 (moderate) |
| Power supply | Not required (passive) | Required (5–15 V) |
| Open circuit | Dangerous (high voltage) | Safe |
| Cost | Low–medium | Medium–high |
3. When to Choose a CT
- AC-only measurement: power monitoring, energy metering, protection relays
- High accuracy: revenue metering (class 0.1–0.5)
- No power supply available: passive operation is critical
- Cost-sensitive high-current AC measurement
4. When to Choose Hall Effect
- DC current measurement: battery management, motor drives (DC link)
- Wide bandwidth: from DC to high frequency
- Compact size: Hall sensors are smaller for same current
- Bidirectional measurement
5. Applications
| Application | Preferred |
|---|---|
| Energy metering (kWh) | CT (high accuracy, AC) |
| Battery management (DC) | Hall sensor |
| Motor drive phase current | Hall (AC+DC) or CT (AC) |
| Solar inverter DC monitoring | Hall sensor |
| Protection relay (AC) | CT |
6. Sirui-Tech Products
- Current transformers: PCB mount, window-type, Rogowski coil
- Hall effect sensors: open-loop and closed-loop
- Custom solutions: specific current ranges and accuracy
Conclusion
Choose a CT for accurate AC measurement without external power. Choose Hall effect for DC measurement or bidirectional sensing. For solar inverters and battery systems, Hall sensors are standard. For power metering and protection, CTs remain the accuracy benchmark.
Need current sensing products? Contact Sirui-Tech at sales@sirui-tech.com with your current range and accuracy requirement.