Thermal overload relays, For contactor mounting - Class 10 - Screw Terminals - 3MU7110-0NA0

Product Description

Siemens 3MU7110-0NA0 Thermal Overload Relay – Class 10 Reliable Motor Protection

The Siemens 3MU7110-0NA0 Thermal Overload Relay is a dependable motor protection device from the SINOVA 3MU7 Series, designed to protect three-phase motors against overload and phase failure conditions. With a 9A to 13A adjustable current range, Class 10 trip characteristic, and direct mounting compatibility with Siemens 3MT7 contactors, this relay provides reliable thermal protection for industrial motor control applications.

Engineered for accurate motor protection, the relay continuously monitors motor current and responds to overload conditions before excessive heat can damage motor windings or insulation. Its thermal bimetal operating principle closely follows actual motor heating characteristics, providing dependable inverse-time overload protection while minimizing nuisance trips during normal operation.

The Class 10 tripping characteristic makes the 3MU7110-0NA0 ideal for motors operating under normal starting conditions. It provides rapid response to overload situations while allowing standard motor acceleration during startup. Common applications include pumps, fans, compressors, conveyors, HVAC equipment, machine tools, and industrial automation systems.

Featuring an adjustable current setting range of 9A to 13A, the relay allows users to precisely match protection settings to the motor's full-load current requirements. The rated operational current is 13A, supporting motors up to approximately 5.5 kW at 400V and 7.5 kW at 690V.

A major advantage of the Siemens 3MU7110-0NA0 Thermal Overload Relay is its integrated phase-failure sensitivity. In the event of phase loss, the relay accelerates tripping to minimize motor overheating and prevent costly winding damage. This enhances operational safety and improves motor reliability in demanding industrial environments.

The relay is designed for direct mounting on Siemens 3MT7 Size 1 and Size 2 contactors, creating a compact and efficient motor starter assembly. Robust screw terminal connections on both the main and auxiliary circuits ensure secure wiring, easy installation, and long-term reliability.

For monitoring and control functions, the relay includes 1 Normally Open (NO) auxiliary contact for trip indication and 1 Normally Closed (NC) auxiliary contact for contactor disconnection. These contacts can be used for alarm signaling, PLC interfacing, and motor protection circuits.

The 3MU7110-0NA0 supports both manual and automatic reset modes, allowing users to select the most suitable reset method based on application requirements and safety considerations. It also features a visible trip indicator for quick fault identification and maintenance.

Designed according to IEC 60947-4-1 standards, the relay offers 690V insulation voltage, 6kV impulse withstand voltage, IP20 front protection, and reliable operation across ambient temperatures from -5°C to +55°C. Its rugged design makes it suitable for manufacturing plants, process industries, water treatment facilities, HVAC systems, and industrial automation projects.