Siemens 3RT2045-1KB44-3MA0 Contactor 80A, 37kW, 24V DC, S3 Original Brand New

Overview

The Siemens SIRIUS 3RT2045-1KB44-3MA0 is a high-performance, 3-pole power contactor designed for reliable switching of electric motors and general loads up to 80 A (AC-3e/AC-3) and 37 kW at 400 V. Part of the globally recognized SIRIUS 3RT2 series, this robust component features a highly efficient 24 V DC control coil with an extended operating range (0.8−1.2×Uc​).

Crucially, it includes an integrated varistor for coil protection against voltage surges, ensuring maximum reliability and longevity, especially when controlled by sensitive devices. Its captive auxiliary switch block provides a standard configuration of 1 NO + 1 NC contacts, ideal for interlocking and signaling purposes. The compact frame size S3 and secure screw terminals make installation straightforward in various industrial environments.

Key Product Specification

• Product ID: 3RT2045-1KB44-3MA0
• Manufacturer: Siemens
• Series: SIRIUS 3RT2
• Contactor Type: Power Contactor (AC switching)
• Poles: 3-pole
• Rated Operational Current (Ie): 80 A (at $400\text{ V}$, AC-3e/AC-3)
• Rated Operational Power (Pe): 37 kW (at $400\text{ V}$)
• Control Coil Voltage: 24 V DC (with integrated varistor)
• Auxiliary Contacts: 1 NO + 1 NC (Captive/Permanent Mount)
• Terminal Type: Screw Terminal
• Frame Size: S3
• Special Feature: Suitable for PLC outputs (low holding power)

Benefit & Features

• High Performance: Excellent switching capacity for motors up to 37 kW, suitable for demanding industrial applications.
• Enhanced Coil Protection: The integrated varistor protects the DC coil from potentially damaging voltage peaks, increasing the contactor’s lifespan.
• PLC Compatibility: Low holding power and optimized coil design make it perfectly suitable for PLC outputs, ensuring reliable operation from automation controllers.
• Reliable Signaling: Comes standard with a captive auxiliary switch block (1 NO + 1 NC), simplifying wiring and ensuring permanent presence of auxiliary contacts for feedback and interlocks.
• Robust & Compact: Features the compact S3 frame size from the SIRIUS line, saving panel space without sacrificing performance.

Function & Application

The 3RT2045-1KB44-3MA0 contactor is primarily used for:

• Switching 3-phase AC motors (Direct On Line (DOL) operation).
• Switching resistive loads.
• Integration into automated control systems (e.g., in conjunction with PLCs).
• Applications requiring precise DC control for the coil, benefiting from the varistor-integrated design.

Technical Detail

• Rated Control Supply Voltage: $24\text{ V DC}$
• Operating Range (Coil): 0.8−1.2×Uc​
• Insulation Voltage (Ui): $1000\text{ V}$
• Degree of Protection: IP20 (Terminal protection against accidental contact)
• Standards: IEC 60947, UL, CSA, etc.

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