Siemens 3RT2637-1AF03 Capacitor Contactor, 75 kVAr, 400V, 110V AC Coil, 1NO+1NC Aux, S2 Size Original Brand New

Overview

The Siemens 3RT2637-1AF03 is a high-performance capacitor contactor specifically engineered for the reliable switching of capacitive loads (AC-6b) up to 75 kVAr at 400V. As part of the SIRIUS 3RT2 series, this robust size S2 contactor is designed with a 110V AC, 50 Hz coil and features leading auxiliary contacts that engage precharging resistors. This intelligent design effectively limits the peak charging current, minimizing disturbances and negative impacts on the power supply network. Equipped with 1 NO and 1 NC auxiliary contacts and secure screw terminals, the 3RT2637-1AF03 is an essential component for reactive current compensation systems and for switching converters.

Key Features & Benefit

• Optimized for Capacitive Loads: Specifically designed for AC-6b applications, ensuring safe and reliable switching of capacitors in reactive power compensation systems.
• Surge Current Limitation: Integrated precharging resistors, activated by leading auxiliary contacts, dramatically reduce inrush current peaks, protecting both the contactor and the power grid.
• Versatile Application: Suitable for switching both choked and unchoked capacitors, as well as converters, providing flexibility in various industrial settings.
• Standardized Compliance: Meets a wide range of international standards including IEC 60947-1, IEC 60947-4-1, and IEC 60831-1, guaranteeing quality and safety.
• Convenient Integration: Features a 110V AC coil for common control circuit applications and includes 1 normally open (NO) and 1 normally closed (NC) auxiliary contact for monitoring and control.
• Secure & Easy Wiring: The reliable screw terminals ensure a strong, stable connection for easy installation and maintenance.
• Robust & Compact Design: The size S2 frame is built for durability and efficient use of space within control panels.

Function

The Siemens 3RT2637-1AF03 functions by using a clever two-stage switching process. When the contactor is energized, leading auxiliary contacts close first, bringing precharging resistors into the circuit. These resistors absorb the initial high inrush current from the capacitive load. A few milliseconds later, the main contacts close, bypassing the resistors and providing the full current path. This mechanism protects the main contacts from welding and extends the overall lifespan of the device.

Technical Specifications

• Product Number: 3RT2637-1AF03
• Application: Capacitor Contactor for AC-6b
• Rated Power (AC-6b): 75 kVAr at 400V
• Number of Poles: 3-pole
• Operating Coil Voltage: 110V AC, 50 Hz
• Auxiliary Contacts: 1 NO + 1 NC
• Terminal Type: Screw terminals
• Size: S2
• Standards: IEC 60947-1, IEC 60947-4-1, IEC 60947-5-1, IEC 60831-1, IEC 61921

Protection and Installation

For optimal performance and safety, proper protection measures must be implemented.

• Main Connections: Short-circuit and overload protection are required. For detailed guidance on protection for free-standing contactors or device combinations (e.g., with overload relays or circuit breakers), refer to the technical product data sheet and digital configuration manuals.
• Auxiliary & Control Circuits: The control supply voltage connections and auxiliary circuits must also be protected against short circuits and overloads. The use of suitable power supplies with current-limiting functions or miniature circuit breakers is recommended.
• Overvoltage Protection: The contactor can be retrofitted with surge suppressors (RC elements, varistors, etc.) to dampen opening surges in the coil, which helps to increase device longevity. Note that this may slightly increase the break times.

Expansion Possibilities

While the 3RT2637-1AF03 has integrated auxiliary contacts for the precharging resistors and a pre-mounted 2-pole lateral auxiliary switch (1 NO + 1 NC), it can be further expanded. Additional lateral auxiliary switches can be mounted to meet specific control panel requirements.

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