Microprocessor based overload relay - 3RB (Class 5 to 30E – Settable) - 3RB3123-4VB0

Product Description

Siemens 3RB3123-4VB0 Electronic Overload Relay – Advanced Microprocessor-Based Motor Protection Solution

The Siemens 3RB3123-4VB0 Electronic Overload Relay is an intelligent motor protection device designed to deliver highly accurate and reliable protection for industrial motors operating in demanding environments. Part of the globally trusted Siemens SIRIUS 3RB3 Series, this microprocessor-based overload relay provides advanced protection against overload conditions, phase failure, phase imbalance, and ground faults while ensuring maximum motor reliability and operational safety. The 3RB3123-4VB0 features a 10A to 40A adjustable current range, selectable Class 5E, 10E, 20E, and 30E trip classes, and integrated electronic monitoring technology, making it a preferred choice for modern industrial automation systems.

Unlike traditional thermal overload relays that rely on bimetal elements, the Siemens 3RB3123-4VB0 utilizes advanced microprocessor-controlled sensing technology to continuously monitor motor current. This electronic monitoring system delivers significantly greater accuracy and repeatability compared to conventional overload protection devices. By detecting overload conditions quickly and precisely, the relay helps prevent motor winding damage, insulation degradation, overheating, and costly equipment failures. This results in increased equipment lifespan, improved productivity, and reduced maintenance expenses.

One of the most valuable features of the 3RB3123-4VB0 Electronic Overload Relay is its adjustable trip class capability. Engineers can select between Class 5E, Class 10E, Class 20E, and Class 30E depending on motor starting characteristics and application requirements. Fast-starting motors can be protected using lower trip classes, while heavy-duty applications requiring longer acceleration times can utilize higher trip classes without nuisance tripping. This flexibility makes the relay suitable for pumps, compressors, conveyors, fans, mixers, crushers, HVAC equipment, and industrial process machinery.

The Siemens 3RB3123-4VB0 offers a 10A to 40A motor protection range, making it suitable for a wide variety of three-phase motors. At 400V AC, the relay can protect motors ranging from approximately 5.5 kW to 18.5 kW, while at 500V AC it supports motors from 7.5 kW to 22 kW, and at 690V AC it protects motors from 11 kW to 37 kW. This broad adjustment range provides flexibility for OEMs, panel builders, and maintenance teams while reducing spare-parts inventory requirements.

A significant advantage of the 3RB3123-4VB0 Motor Protection Relay is its integrated ground fault detection system. The relay continuously monitors current flow and can identify ground fault conditions before severe motor or system damage occurs. Ground fault protection improves overall equipment safety, minimizes downtime, and helps maintain uninterrupted operation in critical industrial processes. The relay's ground fault response function provides an additional layer of protection beyond standard overload monitoring.

Designed in the compact S0 frame size, the relay is intended for direct mounting onto Siemens contactors, creating a streamlined motor starter solution. The main circuit and auxiliary circuit both utilize reliable screw terminal connections, ensuring secure wiring, vibration resistance, and long-term electrical reliability. This compact design helps optimize panel space while simplifying installation and maintenance activities.

For enhanced control integration, the Siemens 3RB3123-4VB0 includes 1 Normally Open (1NO) and 1 Normally Closed (1NC) auxiliary contacts. The NC contact is typically used to disconnect the motor starter during overload conditions, while the NO contact provides overload indication and status feedback for PLC systems, alarm circuits, and industrial automation platforms. This integrated contact arrangement improves system monitoring and fault diagnostics.

The relay supports manual reset, automatic reset, and remote reset functions, offering flexibility for different operational requirements. Maintenance personnel can easily restore system operation after fault conditions are resolved, while automated installations can utilize remote reset capabilities for improved process efficiency. Recovery time after overload trips is optimized to support rapid system restoration while maintaining motor safety.

Built according to Siemens' stringent quality standards, the 3RB3123-4VB0 Electronic Overload Relay features a 690V rated insulation voltage, 6kV surge withstand capability, IP20 front protection, and reliable operation across ambient temperatures from -25°C to +60°C. Integrated temperature compensation ensures consistent protection performance regardless of environmental conditions. These features make the relay suitable for manufacturing facilities, water treatment plants, HVAC systems, chemical processing plants, mining operations, and industrial automation applications.

At SBsmart.in, we supply genuine Siemens industrial automation and motor protection products trusted by OEMs, system integrators, panel builders, electrical contractors, and industrial maintenance professionals across India. When you choose the Siemens 3RB3123-4VB0, you receive an authentic Siemens SIRIUS motor protection solution engineered for long-term reliability, superior performance, and maximum equipment safety.