The Siemens 7UG0881-1BU20 is a thermistor motor protection relay designed to protect motors and generators against overheating by continuously monitoring the temperature of motor windings through PTC thermistor sensors. The relay complies with IEC 60947-8 standards and provides reliable thermal protection for rotating electrical machines.
Operating with a wide 110-240V AC/DC auxiliary supply, this compact relay is ideal for industrial motor control applications where early detection of overheating is critical to prevent equipment damage, downtime, and costly repairs. The relay continuously evaluates the resistance of connected PTC sensors and responds instantly when preset temperature thresholds are exceeded.
The device supports multiple operating conditions including sensor healthy, sensor trip, sensor short-circuit, and sensor open-circuit detection, ensuring comprehensive monitoring of motor temperature status. It also offers Auto, Manual, and Remote Reset modes, providing flexibility for different control system requirements.
With its compact 22.5 mm DIN rail-mounted housing, the 7UG0881-1BU20 is suitable for installation in motor control centers (MCCs), pump systems, compressors, conveyors, HVAC systems, industrial automation panels, and process control applications.
• Genuine Siemens thermistor motor protection relay
• Model: 7UG0881-1BU20
• Designed for motor winding temperature monitoring
• Compatible with PTC thermistor sensors
• Wide auxiliary supply voltage: 110-240V AC/DC
• Detects sensor trip, open circuit, and short circuit conditions
• Auto, Manual, and Remote Reset functionality
• Instantaneous thermal trip response
• Compact 22.5 mm DIN rail mounting design
• Suitable for motors, generators, pumps, and compressors
• High reliability and long operational life
| Parameter | Specification |
|---|---|
| Product Series | Siemens 7UG |
| Model Number | 7UG0881-1BU20 |
| Product Type | Thermistor Motor Protection Relay |
| Auxiliary Supply Voltage | 110-240V AC/DC |
| Sensor Type | PTC Thermistor Sensors |
| Protection Function | Motor Overtemperature Protection |
| Relay Outputs | 2 Changeover Contacts (2 C/O) |
| Reset Modes | Auto, Manual, Remote |
| Frequency | 50/60 Hz |
| Mounting Type | DIN Rail Mount |
| Module Width | 22.5 mm |
| Application | Motor & Generator Thermal Protection |
| Brand | Siemens |
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