3UG45122AR20 – Phase Loss/Sequence Monitor Relay – Siemens SIRIUS Series

Ensure operational safety and prevent equipment damage with the Siemens 3UG45122AR20 phase monitoring relay. Designed for industrial control systems, this DIN-rail mounted device detects phase loss, incorrect phase sequence, and voltage asymmetry in 3-phase AC networks (160–690V AC), triggering a relay output to safeguard motors and machinery.

Key Features

• Monitoring Type: Phase Loss & Phase Sequence Detection
• Voltage Range: 160–690V AC (Self-Powered)
• Output: SPDT Relay (1 Form C) | Rating: 3A @ 400V AC
• Trip Range: Configurable for 160–690V AC Systems
• Robust Design: DIN Rail Mount | -25°C to 60°C Operating Temp
• Reliability: Siemens SIRIUS Industrial-Grade Construction

Technical Specifications

• Manufacturer Series: SIRIUS 3UG4
• Base Part Number: 3UG4512
• Circuit Configuration: SPDT (1 Form C)
• Contact Rating: 3A @ 400V AC Resistive Load
• Mounting: Standard 35mm DIN Rail
• Status: Active Production

Typical Applications

• Industrial Motor Protection Circuits
• HVAC Compressor Safety Systems
• Generator and UPS Phase Monitoring
• Production Line Machinery Control Panels
• Pump and Conveyor System Safeguarding

About Siemens

Siemens stands as a global leader in industrial automation with over 170 years of engineering excellence. Their SIRIUS product line represents industry-proven reliability, meeting stringent international standards for safety and performance in harsh environments.

Siemens components are trusted worldwide for precision design and rigorous quality control. This legacy ensures consistent operation in critical applications—from manufacturing plants to infrastructure projects—making Siemens the preferred choice for engineers prioritizing system integrity.

About Phase Monitoring Relays

Phase monitoring relays protect three-phase equipment by continuously analyzing supply conditions. They prevent costly damage caused by phase imbalances, which can lead to motor burnout, erratic operation, or complete system failure in industrial settings.

These devices are essential in automation panels where voltage irregularities pose safety risks. By instantly disconnecting loads during faults, they minimize downtime, reduce maintenance costs, and extend equipment lifespan—making them indispensable in modern industrial control architectures.

Packaging

This unit ships in protective factory box packaging. Contact PCX for bulk order options.

FAQs

Q: Does this monitor support both 50Hz and 60Hz systems?
A: Yes, it operates universally across standard 50/60Hz AC networks within its voltage range.

Q: Can it detect single-phasing in a 3-phase supply?
A: Absolutely. Phase loss (single-phasing) is a core detection function of this relay.

Q: Is external power required?
A: No. The relay is self-powered directly from the monitored supply voltage (160-690V AC).

Q: What’s the relay’s response time during a fault?
A: Typical response is <200ms, ensuring rapid disconnection upon anomaly detection.

Q: Can this device monitor phase reversal?
A: Yes. Incorrect phase sequence (rotation) triggers the relay output.

Q: Is DIN rail mounting hardware included?
A: Yes, the unit includes integrated DIN rail clips for immediate installation.

Note: Product images are representational. Refer to datasheet for exact dimensions.

Download Full Datasheet: PCXCo.com/datasheets/3UG45122AR20_Siemens

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