The THA-440 is part of a dedicated RCCB series engineered to deliver reliable earth leakage protection across three-phase electrical installations. Rated at 40A with a 30mA sensitivity threshold, this 4-pole device is purpose-built for distribution boards where both AC and pulsating DC residual currents must be detected and interrupted swiftly.
Constructed from high-grade thermoplastic in a clean white finish, the THA-440 is designed for DIN rail mounting and fits standard distribution boards with ease. Its Type A classification ensures compatibility with modern loads — including variable speed drives, inverters, and switched-mode power supplies — that may generate pulsating DC leakage components.
Targeting electrical contractors, panel builders, and facility engineers in commercial buildings, industrial plants, and shopfront installations, the THA-440 delivers consistent tripping performance, long service life, and compliance with IEC 61008-1.
The THA-440 RCCB is engineered to protect personnel and property from the hazards of earth leakage faults and electric shock in three-phase, four-wire electrical systems. Operating at a rated voltage of 415V~ and a frequency of 50/60Hz, the device monitors the vector sum of currents flowing through all four poles. When an imbalance equal to or exceeding the 30mA sensitivity threshold is detected — indicating current escaping to earth — the internal tripping mechanism operates within milliseconds to disconnect the circuit.
The device is housed in a durable white thermoplastic body with clearly labelled terminals (L1, L2, L3, N) and screw-type connections that accept conductors from 1.5 mm² to 25 mm². Its compact footprint — 90.4 mm (H) × 70 mm (W) × 75.3 mm (D) — is optimised for standard distribution board layouts, making it a practical choice for panel builders working to tight space constraints.
With a rated conditional short-circuit current of 6kA and an impulse withstand current of 500A, the THA-440 is built to maintain performance integrity under real-world network conditions. Its long electrical and mechanical service life reduces maintenance frequency and total cost of ownership across the installation lifecycle.
The THA-440 operates on the principle of a toroidal current transformer that continuously monitors the algebraic sum of currents in all four poles. Under normal conditions, the sum is zero; any deviation caused by a leakage path to earth generates a differential signal in the sensing coil. When this signal reaches the 30mA trip threshold, an electromechanical relay releases the latching mechanism, driving the contacts to the open position via a spring-actuated switching assembly. As a Type A device, the sensing circuit is responsive to both sinusoidal AC and pulsating DC residual currents, addressing the leakage profiles generated by rectifier-based and inverter-driven equipment.
The screw-terminal contact assembly is rated for conductors up to 25 mm², and the mechanical switching mechanism incorporates a test button circuit that injects a simulated fault current to verify correct operation of the entire detection and tripping chain without interrupting the supply.
| Model | THA-440 |
|---|---|
| Product Type | Residual Current Circuit Breaker (RCCB) |
| Type | Type A (AC + Pulsating DC) |
| Poles | 4P |
| Rated Current (In) | 40A |
| Rated Voltage (Un) | 415V~ |
| Frequency | 50/60Hz |
| Sensitivity (IΔn) | 30mA |
| Rated Conditional Short-Circuit Current | 6kA |
| Impulse Withstand Current (Im) | 500A |
| Terminal Type | Screw terminal |
| Number of Terminals | 8 |
| Terminal Identifiers | L1 / L2 / L3 / N |
| Clamping Connection Capacity | 1.5 mm² – 25 mm² |
| Mounting | DIN rail |
| Height | 90.4 mm |
| Width | 70 mm |
| Depth | 75.3 mm |
| Degree of Protection | IP20 |
| Ambient Operating Temperature | -5 °C … 40 °C |
| Relative Humidity | 0 … 95% |
| Environmental Use | Indoor |
| Enclosure Material | Thermoplastic, white |
| Operation | Mechanical switching with test button |
| Standards Compliance | IEC 61008-1 |
| Quantity per Set | 1 |
| Weight | TBD |
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