Microprocessor based overload relay - 3RB (Class 20E) - 3RB3026-2QB0

Product Description

Siemens 3RB3026-2QB0 Electronic Overload Relay – Class 20E Motor Protection for Heavy-Duty Applications

The Siemens 3RB3026-2QB0 Electronic Overload Relay is a microprocessor-based motor protection relay from the highly reliable SIRIUS 3RB3 series, designed to protect three-phase motors against overload, phase failure, and phase imbalance conditions. Engineered for industrial automation and motor control applications, this solid-state overload relay delivers precise inverse-time protection and helps prevent costly motor failures caused by excessive current and thermal stress. The relay features a 6A to 25A adjustable current range, Class 20E tripping characteristic, and compact S0 frame size, making it suitable for motors with heavy starting requirements.

Unlike conventional thermal overload relays that use bimetallic elements, the Siemens 3RB3026-2QB0 utilizes advanced electronic sensing and microprocessor-controlled evaluation. This technology continuously monitors motor current and thermal conditions to provide highly accurate overload protection. By responding quickly to abnormal operating conditions, the relay helps prevent winding damage, insulation deterioration, and unexpected production downtime.

A major advantage of the 3RB3026-2QB0 Electronic Overload Relay is its Class 20E tripping characteristic. This protection class is specifically designed for motors that experience extended acceleration periods or heavy-duty startup loads. Applications such as conveyors, crushers, mixers, pumps, compressors, and material handling equipment often require longer starting times. The Class 20E characteristic allows these motors to start normally while still providing dependable protection against prolonged overload conditions.

The relay provides an adjustable current setting range of 6A to 25A, enabling protection for a wide variety of industrial motors. According to Siemens specifications, it supports approximately 3–11 kW motors at 400V, 4–15 kW motors at 500V, and 5.5–22 kW motors at 690V. This flexibility helps OEMs, panel builders, and maintenance engineers standardize motor protection solutions across multiple installations.

Integrated phase failure and phase imbalance protection continuously monitor all three phases of the motor supply. If a phase is lost or becomes significantly unbalanced, the relay automatically trips the motor circuit before overheating and damage occur. This proactive protection significantly improves motor reliability and reduces maintenance costs.

The 3RB3026-2QB0 is designed for direct mounting onto compatible Siemens 3RT2023 to 3RT2028 contactors, creating a compact and efficient motor starter assembly. The relay features robust screw-type terminals for both main and auxiliary circuits, ensuring secure electrical connections and reliable long-term operation in industrial environments.

For monitoring and control applications, the relay includes 1 Normally Open (1NO) and 1 Normally Closed (1NC) auxiliary contacts. These contacts can be used for overload trip indication, PLC integration, alarm signaling, fault diagnostics, and control circuit interruption. The integrated contact arrangement simplifies panel wiring and enhances system visibility.

The relay supports both manual and automatic reset modes, allowing users to select the most suitable recovery method for their application. This flexibility makes the device ideal for both automated production systems and manually supervised motor control installations.

Built according to IEC 60947-4-1 standards, the Siemens 3RB3026-2QB0 Electronic Overload Relay offers IP20 protection, 690V rated insulation voltage, 6kV impulse withstand capability, and reliable operation in ambient temperatures ranging from -25°C to +60°C. Its rugged design and advanced protection technology make it ideal for manufacturing plants, HVAC systems, water treatment facilities, packaging machinery, and industrial automation projects.

At SBsmart.in, we supply genuine Siemens industrial automation and motor protection products trusted by OEMs, panel builders, electrical contractors, and maintenance professionals across India.