Siemens 3RT2327-1BB40 Contactor AC-1, 50A, 4-Pole, 24V DC, S0 Size Screw Terminal Original Brand New

Overview

The Siemens 3RT2327-1BB40 is a robust 4-pole contactor, specifically designed for AC-1 applications, ideal for switching non-inductive or weakly inductive loads up to 50 A (at 400 V and 40 °C). Part of the SIRIUS 3RT2 series, this size S0 contactor features a reliable 24 V DC operating mechanism and convenient screw terminals for secure wiring. It comes equipped with integrated 1 Normally Open (NO) and 1 Normally Closed (NC) auxiliary contacts, offering enhanced control and feedback capabilities for diverse industrial and power generation applications. Its compact design and adherence to international standards make it a versatile choice for disconnecting loads, power generation plants from the grid, and transfer switching tasks.

Function

The Siemens 3RT2327-1BB40 contactor serves as an electromagnetic switch for controlling power circuits. When the 24 V DC control voltage is applied to its coil, the main contacts close, allowing current to flow to the connected load. Conversely, when the control voltage is removed, the coil de-energizes, opening the main contacts and disconnecting the load. The integrated 1 NO + 1 NC auxiliary contacts provide signaling or interlocking functions within control circuits, indicating the main contactor’s status (open or closed). It is specifically engineered for AC-1 duty, making it suitable for resistive or slightly inductive loads such as heating elements, lighting, and power distribution systems.

Benefit

• Reliable Performance: Built to Siemens’ high quality standards, ensuring long-term operational stability and safety in demanding industrial environments.
• Versatile Application: Ideal for four-pole switching of weak or non-inductive loads (AC-1), disconnecting loads or power generation plants from the grid, and transfer switching.
• Integrated Auxiliary Contacts: The pre-installed 1 NO + 1 NC auxiliary contacts simplify wiring and provide essential status feedback for control systems.
• Easy Installation: Screw terminals offer a secure and straightforward connection for main, auxiliary, and control circuits.
• Compact Design (Size S0): Optimizes panel space, contributing to more efficient control cabinet layouts.
• DC Coil Operation: Provides consistent and reliable switching performance, particularly in systems utilizing 24V DC control.
• Standards Compliant: Meets international IEC standards, ensuring compatibility and safety in global applications.
• Expandability: Supports the addition of further auxiliary switches for enhanced control flexibility.

Technical Details & Protection

Protection of Device Connections: All connections, including main, auxiliary, and control supply voltage, require appropriate short-circuit and overload protection.

• Main Connections: For a free-standing contactor, consult the technical product data sheet for specific protection recommendations. For combinations with overload relays or circuit breakers (motor feeders), refer to the “Digital Configuration Manual for load feeders” and “Configuration Manual for load feeders.”
• Auxiliary Connections: Refer to the technical product data sheet for information on auxiliary contact protection.
• Control Supply Voltage: Adhere to relevant standards for control panel configuration and cable dimensioning. Protection can be achieved through suitable current-limiting power supplies or appropriately sized miniature/circuit breakers, considering the contactor’s load characteristics (inrush current, switch-on power, holding power).

Protection against Overvoltage at Control Supply Voltage: The 3RT23 contactors (when supplied without coil circuit) can be retrofitted with external surge suppressors like RC elements, varistors, diodes, or diode assemblies (ordered separately as accessories) to damp opening surges in the coil. Note that damping increases contactor break times and auxiliary contact delay times.

Connection Methods:

• Main Circuit: Screw terminals.
• Auxiliary and Control Circuit: Screw terminals.

Electromagnetic Compatibility (EMC): The contactors meet requirements for environment category A. For use with frequency converters, observe configuration notes in the Equipment Manual.

Contact Reliability of Auxiliary Contacts: For switching voltages $\le$ 110 V and currents $\le$ 100 mA, the 3RT auxiliary contacts guarantee high contact reliability, particularly suitable for solid-state circuits with currents $\ge$ 1 mA at 17 V and higher.

Motor Protection: While the 3RT2327-1BB40 is an AC-1 contactor, for applications requiring motor overload protection, 3RU2 thermal overload relays or 3RB3 electronic overload relays can be directly mounted onto 3RT23 contactors.

Operating Mechanism: This version features a conventional 24 V DC operating mechanism, controlled via terminals A1-A2.

Replacing Solenoid Coils/Contacts: Solenoid coil replacement is possible. For 3RT233 contactors, contacts can also be replaced (note: this specific model is 3RT2327, so contact replacement may vary – refer to the technical data sheet).

Auxiliary Contact Configuration: The 3RT2327-1BB40 (a 3RT232 model) comes with two integrated auxiliary contacts (1 NO + 1 NC) in the basic unit. All basic units can be expanded with additional auxiliary switches, adhering to permissible configurations.

Accessories and Spare Parts: A wide range of accessories and spare parts are available for SIRIUS 3RT2 contactors, including surge suppressors and additional auxiliary switches, to customize and maintain your setup.

Application

The Siemens 3RT2327-1BB40 contactor is ideal for:

• Four-pole switching of weak or non-inductive loads (AC-1)
• Disconnecting loads or power generation plants from the grid
• Transfer switching

For specialized applications involving switching motor-driven loads (AC-3), Siemens offers dedicated 3RT23 contactor versions.

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