Siemens Overload relay for motor protection, size S0, 5.5 - 8A Part number 3RU2126-1HB0

Product Overview

The Siemens 3RU2126-1HB0 is a SIRIUS thermal overload relay designed to protect three-phase motors against overload and phase failure. Part of the 3RU21 series, this relay features an adjustable current setting range of 5.5 A to 8 A and a Class 10 tripping characteristic, ensuring reliable protection under standard motor starting conditions. It is intended for direct mounting onto compatible SIRIUS contactors, forming a compact and dependable motor starter solution for industrial control systems.

Key Features

• SIRIUS thermal overload relay for motor protection
• Adjustable current setting range from 5.5 A to 8 A
• Class 10 tripping characteristic for standard motor applications
• Reliable protection against overload and phase failure
• Direct mounting onto compatible SIRIUS contactors
• Integrated auxiliary contacts for signaling and control
• Manual or automatic reset selectable
• Compact design for space-efficient motor starter assemblies

Technical Specifications

• Article Number: 3RU2126-1HB0
• Product Family: SIRIUS 3RU21 Thermal Overload Relays
• Device Type: Thermal overload relay
• Frame Size: S0
• Current Setting Range: 5.5 – 8 A
• Tripping Class: Class 10
• Number of Poles: 3
• Auxiliary Contacts: 1 NO + 1 NC
• Mounting: Direct mounting on SIRIUS contactors
• Reset Options: Manual or automatic
• Rated Insulation Voltage: 690 V
• Surge Withstand Voltage: 6 kV
• Ambient Operating Temperature: −40 °C to +70 °C

Compliance & Standards

• Designed in accordance with IEC 60947-4-1
• Meets Siemens SIRIUS requirements for motor protection devices
• Suitable for global industrial motor control applications

Applications

The Siemens 3RU2126-1HB0 thermal overload relay is used to protect three-phase motors in industrial machinery, pumps, fans, compressors, and conveyor systems. When combined with a compatible SIRIUS contactor, it forms a compact motor starter that ensures reliable protection against overload conditions and phase loss, supporting safe and efficient operation in automation and control panels.