Schneider Thermal Overload Relay LRD340

Schneider Electric LRD340 Thermal Overload Relay — Reliable Medium-Duty Motor Protection

The Schneider Thermal Overload Relay LRD340 is a robust and dependable three-pole protection device designed for safeguarding medium-power three-phase motors against prolonged overcurrent, phase loss, and load imbalance in industrial and commercial electrical systems. Part of Schneider Electric’s TeSys LRD series, this relay offers precise thermal protection with adjustable settings — making it an excellent choice for motor control panels, starter assemblies, and machinery installations across India.

🔌 What Is the Schneider LRD340 Thermal Overload Relay?

The LRD340 is a thermal overload relay engineered to work with Schneider contactors (like LC1D40A, LC1D50A, and LC1D65A) to form complete motor starter solutions. It continuously monitors current in all three phases and trips the motor circuit when sustained overload or abnormal phase conditions occur, helping protect motors from overheating and potential damage.

🛠️ Key Features & Benefits

• Adjustable Current Protection (30 – 40 A) — Allows precise tuning to a motor’s full-load current for tailored thermal protection.

• Class 10A Tripping Characteristic — Balances tolerance for start-up inrush currents with swift response to prolonged overloads, aligning with IEC motor protection standards.

• Three-Pole Thermal Monitoring — Monitors all phases for balanced operation and overload detection.

• Phase Loss & Unbalance Detection — Trips the circuit when abnormal phase conditions are detected to reduce stress on motors.

• Manual/Automatic Reset & Test Functions — Provides flexibility on reset behaviour and easy operational checks without interrupting power.

• Auxiliary Contacts (1NO + 1NC) — Allows signalling to control panels or automation systems for fault indication.

• Secure Screw-Clamp or EverLink Terminals — Reliable, vibration-resistant power and control wiring connections.

• Mounting Flexibility — Supports direct mounting beneath compatible contactors or DIN-rail/panel installation.

⚙️ Why Use the LRD340 Overload Relay?

Thermal overload relays like the LRD340 are essential in protecting three-phase motors from overheating and related failures due to prolonged overcurrent, phase faults, or unbalanced loads. By detecting unsafe thermal conditions and disconnecting power before damage occurs, the LRD340 helps:

• Prevent costly motor damage and insulation breakdown

• Reduce unplanned downtime and maintenance overhead

• Improve system safety with early fault detection

• Enhance motor life through reliable protection mechanisms

• Integrate smoothly with Schneider contactors for compact motor starter assemblies

📌 Typical Applications

The Schneider Thermal Overload Relay LRD340 is ideal for:

• Motor starter assemblies in industrial control panels

• Pumps, compressors & fans

• Conveyor and material handling systems

• HVAC motors and ventilation drives

• Production machinery and electrical control cabinets

Used widely in factories, workshops, and automated systems, it ensures dependable overload protection for three-phase motors.