A current sensor (CT) is a component used in electrical equipment, specifically within a Power Quality Analyzer, to measure alternating current (AC) flowing through a conductor. It operates non-invasively, meaning it does not require direct electrical connection to the circuit. The sensor provides an isolated, proportional electrical signal to the analyzer's processing unit, which then calculates power parameters, performs harmonic analysis, and detects power quality issues. The working principle is based on electromagnetic induction: the current-carrying conductor acts as a primary winding, and the alternating magnetic field induces a proportional current in the sensor's secondary winding. This induced current is converted to a low-voltage signal suitable for measurement. Typical materials include a ferromagnetic core (e.g., silicon steel or nanocrystalline), copper wire, insulation materials, and a protective housing (e.g., plastic or resin). Key parameters to consider when selecting a current sensor include rated current (5–5000 A), accuracy class (0.5–1.0), output signal (0–5 V AC), insulation voltage (0.72–36 kV), rated frequency (50–60 Hz), thermal short-circuit current (20–100 kA), dynamic short-circuit current (50–250 kA), operating temperature (-40 to 85 °C), degree of protection (IP54–IP65), rated burden (2.5–30 VA), and weight (1–50 kg). These values are reference ranges and must be confirmed for the specific model and application. Standards such as IEC 61869-1, IEC 61869-2, and IEC 60529 are referenced for verification. Always verify model-specific values and standards with the legal manufacturer or supplier before procurement.
The current sensor operates on the principle of electromagnetic induction. The primary conductor, through which the current to be measured flows, acts as a single-turn primary winding. The alternating magnetic field generated by this current links with the secondary winding wound around a ferromagnetic core. This induces a secondary current proportional to the primary current. The secondary current is then converted to a low-voltage signal, typically 0–5 V AC, which is isolated and safe for the analyzer's electronics. The core material and winding design determine the accuracy and frequency response. The sensor does not require direct electrical contact with the primary circuit, ensuring safety and minimal intrusion.
