Schneider Thermal Overload Relay LRD12

Schneider Electric LRD12 Motor Protection Relay — Reliable Thermal Overload Protection for Three-Phase Motors

The Schneider Thermal Overload Relay LRD12 is a trusted industrial motor protection device designed to safeguard three-phase motors and electrical circuits from prolonged overcurrent and overheating. As part of the Schneider Electric TeSys LRD series, this relay delivers essential overload protection, helping prevent motor damage, reduce downtime, and enhance the safety and longevity of electrical systems.

🔌 What Is the Schneider LRD12 Thermal Overload Relay?

The Schneider LRD12 is a three-pole thermal overload relay with an adjustable current range of 5.5–8 A, engineered specifically to protect small to medium three-phase motors up to roughly 3 kW at 400 V AC. Its thermal sensing mechanism detects excessive current due to overload or prolonged operation and trips the circuit to prevent motor winding damage and overheating.

Designed to be compact and easy to install, the LRD12 can be used with Schneider TeSys contactors (e.g., LC1D09–LC1D38) to form a complete motor starter assembly.

🛠️ Key Features & Benefits

• Adjustable Current Setting (5.5–8 A) – Fine-tune protection to match motor full-load current for optimal safeguarding.

• Class 10A Tripping Curve – Typical trip response within ~10 seconds when overload conditions persist, balancing protection with normal start-up currents.

• Three-Pole Protection – Monitors all three phases of the motor circuit to prevent phase loss or unbalance damage.

• Phase Loss/Unbalance Sensitivity – Detects abnormal current conditions that can harm motors and cuts power quickly.

• Auxiliary Contacts (1NO + 1NC) – Provides signalling and integration with control panels or automation systems for enhanced safety and monitoring.

• Manual/Automatic Reset & Test Button – Choose convenient reset behavior and test relay function easily without removing power.

• Screw-Clamp Terminals – Secure wiring connections that resist vibration and support reliable control circuit integration.

• Compact Industrial Design – Easy to mount on DIN rails or directly beneath compatible contactors, saving panel space.

🔧 Why Use a Thermal Overload Relay?

In industrial and commercial electrical systems, motors can experience extended start-up currents, unbalanced loads, phase loss, or mechanical overloads — all of which can cause excessive heat and winding damage. The Schneider LRD12 Thermal Overload Relay:

• Protects motors from overheating and potential failure, improving equipment life

• Minimises downtime by tripping before damage occurs and signalling faults

• Reduces maintenance costs by preventing unpredictable motor failures

• Enhances system safety by integrating with control logic and monitoring circuits

This protection relay is especially useful in motor starters, control panels, and automated systems where reliable motor safeguarding is essential.

📌 Typical Applications

• Motor starter assemblies with TeSys contactors

• Industrial three-phase motor control

• HVAC systems & ventilation drives

• Pumps, compressors, and conveyors

• Control panels in manufacturing or commercial facilities