A leakage current sensor, also known as a residual current sensor, is specifically designed to detect small, unwanted currents leaking to ground. Its core principle is based on measuring the vector sum of all currents in a circuit. In a single-phase system, both the line and neutral conductors pass through the sensor's core. In a three-phase system, all phase conductors and the neutral (if used) pass through. Under normal, fault-free conditions, the magnetic fields generated by these currents cancel each other out, resulting in zero net magnetic flux. However, if a leakage current occurs (e.g., through insulation failure or a person), the balance is disturbed, creating a net magnetic field that induces a measurable signal in the sensor's output.
Product Features
1. High Sensitivity: It is engineered to detect very low levels of leakage current (from milliamps to amps), which are crucial for personal safety and equipment protection.
2. Core Balance Principle: It intentionally ignores the high, normal load currents and only responds to the difference or imbalance current (residual current), making it highly selective.
3. Critical Safety Device: Its primary function is not power measurement but proactive safety, providing the essential signal to trigger protective devices like circuit breakers.
Common Applications
These sensors are fundamental for electrical safety across various sectors:
1. Ground Fault Circuit Interrupters (GFCIs/RCDs) in residential, commercial, and industrial electrical installations.
2. Equipment Monitoring in medical devices (e.g., MRI machines, patient monitoring systems) and IT equipment racks to ensure safety.
3. Insulation Monitoring in solar PV systems, industrial motor drives, and uninterruptible power supplies (UPS).
