Siemens 3RT2645-1AB03 Capacitor Contactor, 75 kVAr, 400V, 24V AC Coil, 1 NO + 1 NC Aux, Size S3 Original Brand New

Overview

The Siemens 3RT2645-1AB03 is a specialized capacitor contactor from the SIRIUS 3RT2 series, engineered for switching capacitive loads in reactive power compensation systems. This robust contactor is designed to handle switching of choked or unchoked capacitors up to 75 kVAr at 400V (AC-6b). Its core function is to limit high inrush currents, thereby protecting the electrical network and the connected equipment.

The 3RT2645-1AB03 features precharging resistors that are switched on via leading auxiliary contacts, which engage before the main contacts. This crucial design feature minimizes the negative impact of high peak charging currents on the power supply, ensuring stable and reliable operation.

Key Features & Benefits

• Optimized for Capacitive Loads: Specifically designed for AC-6b switching duty, making it ideal for reactive power compensation systems.
• High Inrush Current Limitation: Integrated precharging resistors effectively limit the high peak charging currents, protecting the power grid and extending the life of the capacitors and contactor.
• Robust and Reliable: Built to IEC standards (IEC 60947-1, IEC 60947-4-1, etc.) for industrial applications, ensuring long-term performance and safety.
• Integrated Auxiliary Contacts: Comes with a pre-mounted 2-pole lateral auxiliary switch (1 NO + 1 NC), providing additional control and feedback capabilities.
• Versatile Application: Suitable for switching both choked and unchoked capacitors in reactive current compensation systems and for use with converters.
• Easy Installation: Features a compact size S3 frame and secure screw terminals for straightforward and reliable wiring.
• Flexible Expansion: Can be expanded with additional lateral auxiliary switches to meet more complex control requirements.

Functionality

The Siemens 3RT2645-1AB03 operates by utilizing leading auxiliary contacts to engage precharging resistors before the main contacts close. This sequence limits the initial inrush current that occurs when a capacitor is connected to the power supply. The resistors are then bypassed once the main contacts close, allowing the full current to flow. This mechanism significantly reduces stress on the electrical system and connected components. The integrated auxiliary contacts provide a signal for system monitoring or for controlling other devices within the reactive power compensation panel.

Protection and Safety

The device requires appropriate short-circuit, overload, and overvoltage protection for all connections (main, auxiliary, and control supply). Refer to the technical product data sheet and configuration manuals for specific recommendations on suitable circuit breakers, overload relays, and power supplies. Optional surge suppressors (RC elements, varistors, diodes) can be retrofitted to the coil circuit to dampen opening surges, which must be ordered separately.

Expansion and Accessories

The 3RT2645-1AB03 comes with an integrated 2-pole lateral auxiliary switch and can be further expanded with additional lateral auxiliary switches as required. For a full range of compatible accessories, including surge suppressors and auxiliary switches, please visit the product page on our website.

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