Siemens Power contactor, 3-pole, size S0, 1NO+1NC, 18.5kW Part number 3RT2028-2BB40

Product Overview

The Siemens 3RT2028-2BB40 is a 3-pole power contactor from the SIRIUS 3RT2 series. It is designed to switch and control three-phase motors and other AC loads, offering reliable contact switching for industrial and automation applications. With a 24 V DC coil and integrated auxiliary contacts, this contactor serves as a robust main switching device in motor starters, control panels, and machine installations.

Key Features

• 3-pole power contactor (main contacts for three-phase switching)
• Rated for up to 38 A current — suitable for medium-power motors and AC loads
• Motor power rating up to 18.5 kW at 400 V (AC-3 / AC-3e operation)
• Control coil: 24 V DC — compatible with standard control-voltage circuits
• Includes 1 auxiliary contact (1 NO + 1 NC) for control logic or signalling feedback
• Spring-loaded terminals for secure, reliable wiring and quick installation
• Size designation S0 — compact footprint, suitable for standard control cabinets or motor-starter assemblies
• Insulation voltage rating up to 690 V, with surge voltage resistance up to 6 kV — suitable for industrial environments
• Protection class on the front: IP20 — intended for installation in enclosed control panels or switchgear housing

Technical Specifications

• Article Number (MLFB): 3RT2028-2BB40
• Product Family / Type: SIRIUS 3RT2 — 3-pole power contactor
• Poles (Main Contacts): 3 (for three-phase switching)
• Rated Current (Ie): 38 A
• Rated Motor Power (AC-3 / AC-3e): 18.5 kW @ 400 V
• Control Coil Voltage: 24 V DC
• Auxiliary Contacts: 1 NO + 1 NC
• Terminal Type: Spring-loaded terminals
• Insulation Voltage (pollution degree 3): 690 V
• Surge Voltage Resistance: 6 kV
• Protection Class: IP20 (front) — requires installation inside enclosed panel / cabinet
• Contactor Size: S0
• Designed For: AC-3 / AC-3e load switching (three-phase motors, general industrial loads)

Compliance & Standards

• Part of the SIRIUS 3RT2 range — widely used in industrial motor control and automation.
• Meets standard insulation and surge-voltage resistance requirements for industrial control gear.
• Designed for enclosed-panel installation (IP20) in compliance with typical control-gear housing standards.

Applications

The 3RT2028-2BB40 is well suited for controlling motors and general AC loads in industrial automation, manufacturing, HVAC systems, pumps, conveyors, compressors, and machine-starter assemblies. Its combination of 38 A capacity, 18.5 kW switching capability, and auxiliary contact for feedback/control logic makes it useful in motor starters, contactor-relay control circuits, and as a main switching element in control cabinets for industrial machines and plant equipment.