Schneider Thermal Overload Relay LRD350

Schneider Electric TeSys Deca 37‑50A Thermal Overload Relay LRD350 — Industrial Three-Phase Motor Protection Relay

The Schneider Thermal Overload Relay LRD350 is a rugged and reliable thermal protection device designed to protect medium-size three-phase motors from prolonged overcurrent, phase loss, load imbalance, and overheating. It is part of Schneider Electric’s TeSys LRD range — known for dependable motor safeguarding in industrial, commercial, and automated electrical systems.

Specifically engineered to work with Schneider TeSys contactors (such as LC1D40A, LC1D50A, and LC1D65A), the LRD350 is widely used in motor starter panels, control cabinets, and machinery installations across India where consistent performance and safety are priorities.

🔌 What Is the Schneider LRD350 Thermal Overload Relay?

The Schneider Thermal Overload Relay LRD350 is a three-pole differential thermal overload relay with an adjustable current protection range of 37 – 50 A. It constantly monitors current in all three phases and trips the circuit when sustained overload or phase imbalance is detected, preventing motor winding damage and reducing unplanned downtime.

This relay provides essential protection for motors up to ~22 kW at 400 V AC, making it suitable for medium-duty industrial and commercial applications. The device’s Class 10A tripping characteristic ensures it tolerates short start-up currents but responds reliably to prolonged overloads.

🛡️ Key Features & Benefits

• Adjustable Current Range (37 – 50 A): Allows precise matching to motor full-load current for effective protection.

• Three-Pole Thermal Protection: Monitors all phases, safeguarding motors from overload, phase loss, and unbalance.

• Class 10A Trip Curve: Designed to tolerate normal motor start-up inrush but trip reliably on sustained overloads.

• Auxiliary Contacts (1NO + 1NC): Supports fault signalling, control panel integration, and automation feedback.

• EverLink BTR or Screw Clamp Terminals: Ensures secure, vibration-resistant wiring for power and control circuits.

• Mounting Flexibility: Can be mounted under compatible contactors or on DIN rails/panels for versatile installation.

• Wide Voltage Compatibility: Rated for up to 690 V AC operation at 0–400 Hz, suitable for varied industrial systems.

• Operating Temp Range: Designed for typical industrial environments (e.g., −20 °C to 60 °C).

⚙️ Why Use the LRD350 Overload Relay?

Thermal overload relays such as the Schneider LRD350 are crucial components in motor control systems. By detecting and reacting to sustained overcurrent conditions before damage occurs, this device helps you:

• Prevent motor failure and winding damage due to overheating

• Reduce equipment downtime and maintenance costs

• Improve safety with early fault detection

• Extend motor and system life through reliable protection

• Seamlessly integrate with contactor-based starters for compact panels

This makes the LRD350 ideal for electrical systems where reliable motor protection and operational continuity matter.

📌 Typical Industrial Applications

The Schneider Thermal Overload Relay LRD350 is suitable for:

• Motor starter assemblies with compatible contactors

• Pumps and compressors in industrial loops

• Conveyor and material handling systems

• HVAC motor control and ventilation drives

• Production machinery panels and automated electrical systems

Used in factories, plants, and large commercial installations, this overload relay enhances motor protection and system reliability.