Siemens 3RT2628-1AC25 SIRIUS 3RT26 Capacitor Contactor 33 kVAr, 400V, 24V AC Coil Original Brand New

Overview

The Siemens 3RT2628-1AC25 is a SIRIUS 3RT26 series capacitor contactor specifically engineered for switching capacitive loads in reactive power compensation systems. It is designed to handle loads up to 33 kVAr at 400 V (AC-6b). This special version of the SIRIUS 3RT2 contactor family is distinguished by its integrated precharging resistors. These resistors are switched into the circuit via leading auxiliary contacts, which close moments before the main contacts.

This innovative design limits the peak charging current, effectively minimizing stress on the electrical network and prolonging the life of both the contactor and the capacitors it controls. The 3RT2628-1AC25 features a 24 V AC, 50/60 Hz coil, a robust 3-pole configuration, and a size S0 frame. It comes equipped with 1 normally open (NO) and 2 normally closed (NC) auxiliary contacts and utilizes screw terminals for secure and reliable connections.

Key Features & Benefits

• Optimized for Capacitive Loads: Specifically designed for switching capacitive loads (AC-6b) up to 33 kVAr, ensuring reliable and safe operation in reactive current compensation systems.
• Integrated Precharging Resistors: The leading auxiliary contacts activate precharging resistors, which significantly limit inrush current peaks, protecting the power supply network and extending the lifespan of connected equipment.
• High Performance and Durability: Based on the trusted SIRIUS 3RT2 platform, this contactor offers exceptional reliability and a long service life.
• Versatile Application: Suitable for switching both choked and unchoked capacitors in power factor correction systems, as well as for converter applications.
• Comprehensive Auxiliary Contacts: The built-in 1 NO and 2 NC auxiliary contacts provide flexible options for interlocking, signaling, and control circuits.
• Standardized Compliance: Meets international standards including IEC 60947-1, IEC 60947-4-1, IEC 60947-5-1, IEC 60831-1, and IEC 61921, ensuring quality and safety.
• Easy and Secure Installation: Features screw terminals for straightforward and robust wiring.

Function

The Siemens 3RT2628-1AC25 capacitor contactor is a specialized device used in electrical systems to manage reactive power. It functions by switching capacitors in and out of a circuit to improve the power factor. The unique feature of this contactor is its ability to mitigate the high inrush currents that occur when connecting capacitors. This is achieved through a two-stage process:

1. Precharging: When the contactor is energized, leading auxiliary contacts close first, engaging integrated resistors. These resistors precharge the capacitors, limiting the initial current surge to a safe level.
2. Main Contact Engagement: After a short delay, the main power contacts close, bypassing the resistors and providing a direct path for the full current flow. This sequence protects the system from damaging current peaks, ensuring smooth and reliable operation.

Protection & Safety

• Short-Circuit and Overload Protection: It is essential to protect all connections against short circuits and overloads. Refer to the technical product data sheet for a free-standing contactor or the Siemens Configuration Manuals for integrated load feeder combinations.
• Control Supply Voltage Protection: The control circuit (24 V AC) must be protected using appropriate measures, such as selecting a power supply with a current-limiting function or using suitable circuit breakers.
• Overvoltage Protection: The control circuit can be protected against overvoltage by adding optional surge suppressors (RC elements, varistors, or diodes), which must be ordered separately. Please note that adding suppressors may increase the contactor’s break times.

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