Schneider Thermal Overload Relay LRD3353

Schneider LRD3353 23‑32A Thermal Overload Relay

Reliable Medium-Duty Thermal Motor Protection Relay

The Schneider Thermal Overload Relay LRD3353 is a rugged and dependable protection device engineered to safeguard three-phase motors from prolonged overcurrent, phase loss, and load imbalance in industrial and commercial electrical systems. Part of Schneider Electric’s TeSys LRD series, the LRD3353 provides precise thermal overload protection with adjustable settings — making it ideal for motor control panels, starter assemblies, machinery installations, and automation setups where motor reliability matters.

🔌 What Is the Schneider LRD3353 Thermal Overload Relay?

The LRD3353 is a three-pole thermal overload relay designed to work with Schneider contactors (such as LC1D80 and LC1D95) to form a complete motor starter assembly. It continuously monitors the current in all three phases and disconnects the motor power when sustained overload or abnormal phase conditions occur, preventing overheating and costly motor damage.

This relay features an adjustable current setting range of 23 – 32 A, providing flexible protection for medium-power motors often found in industrial and commercial installations.

🛠️ Key Features & Benefits

• Adjustable Current Range (23 – 32 A) — Enables precise matching to your motor’s full-load current for tailored thermal protection.

• Class 10A Trip Characteristic — Designed to allow normal start-up inrush yet trip reliably on sustained overloads, in line with IEC standards.

• Three-Pole Monitoring — Continuously checks all three phases for overload, phase loss, and unbalance conditions.

• Phase Loss & Load Imbalance Detection — Helps prevent motor damage by reacting quickly to abnormal current conditions.

• Auxiliary Contacts (1NO + 1NC) — Provides signalling options to control panels and automation systems for fault alerting.

• Manual/Automatic Reset & Test Button — Offers flexible reset behaviour and easy verification of relay operation without powering down.

• Secure Screw-Clamp Terminals — Ensures stable, vibration-resistant wiring for power and control circuits.

• Direct or Panel Mounting — Can be installed below compatible contactors or on DIN rail/panels for flexible integration.

These features make the LRD3353 a dependable choice for engineers, electricians, and panel builders seeking effective motor protection in industrial and commercial electrical systems.

⚙️ Why Use the LRD3353 Overload Relay?

Thermal overload relays like the LRD3353 are essential for protecting motors from conditions that can lead to overheating, insulation breakdown, and mechanical wear. By detecting sustained overcurrent and abnormal phase behaviour early, the relay helps you:

• Prevent costly motor damage due to excessive heat

• Enhance system safety with early fault detection and signalling

• Minimise downtime and reduce maintenance interventions

• Extend motor and system life through reliable protection

• Integrate seamlessly with Schneider contactor-based motor starters

📌 Typical Applications

The Schneider Thermal Overload Relay LRD3353 is well-suited for:

• Motor starter assemblies in industrial control panels

• Pumps, fans, and compressors

• Conveyors and material handling lines

• HVAC motor control circuits

• Machine tools and production equipment

• Commercial and factory electrical distributions

Whether you are building new control panels or upgrading existing systems, the LRD3353 enhances motor protection and reliability in three-phase environments.