Schneider Electric LRD Series Thermal Overload Relay Instruction Manual

1. Introduction and Overview

The Schneider Electric LRD series thermal overload relays are designed to provide reliable overload protection for AC circuits, particularly when paired with LC1D contactors. These three-pole thermal magnetic trip relays are known for their compact size, light weight, low power consumption, and long service life, ensuring safety and reliability in industrial control applications.

Please note: Schneider Electric LRD series products are subject to upgrades. The black version represents a newer iteration of the product line.

2. Product Features and Advantages

High-Quality Copper Pins: Equipped with sensitive and stable copper pins, ensuring reliable contact and performance.
Flame-Retardant PC Shell: The robust PC material shell is corrosion-resistant, wear-resistant, and features high flame-retardant properties, contributing to a long and stable operational life.
Accurate Current Setting Dial: Features an accurate and sensitive current setting dial, allowing for continuous adjustment of the overall current to ensure precise and safe operation.
Secure Wiring: Utilizes crimp-type wiring with screw fastening, designed to prevent accidental contact and ensure secure, reliable connections. Silver alloy contacts are used to handle large currents efficiently.

Diagram illustrating key product advantages: high-quality copper pin, flame-retardant shell, accurate current setting dial, and secure wiring with screw fastening. — Figure 1: Key Product Advantages

Image detailing the durable PC material shell of the LRD thermal overload relay, emphasizing its corrosion and wear resistance. — Figure 2: PC Material Shell Durability

3. Product Structure Analysis

The LRD thermal overload relay features a clear and intuitive design for ease of use and maintenance. Key components include:

Copper Pins: For main power connections.
Tripping Indication: Visual indicator for overload events.
Current Setting Dial: Adjustable dial to set the desired current protection range.
Reset Button (Blue): Used to reset the relay after a trip.
Stop Button (Red): Manual stop function.
Normally Open (NO) Contacts (97 NO, 98 NO): Auxiliary contacts for control circuits.
Normally Closed (NC) Contacts (95 NC, 96 NC): Auxiliary contacts for control circuits.
T1, T2, T3 Connection Ports: Output terminals for connecting to the motor or load.

Diagram showing the components of the LRD thermal overload relay, including copper pins, tripping indication, current setting dial, reset button, stop button, normally open and normally closed contacts, and T1, T2, T3 connection ports. — Figure 3: LRD Thermal Overload Relay Structure

Front view of the Schneider Electric LRD thermal overload relay, showcasing its design and main components. — Figure 4: Front View of LRD Relay

Figure 5: Side View of LRD Relay

Dimensional drawing of the LRD thermal overload relay, showing measurements in millimeters. — Figure 6: LRD Relay Dimensions

4. Specifications

4.1 Basic Parameters

Parameter	Value	Parameter	Value
Product Brand	Schneider Electric (Shi Naide Electric)	Product Model	LRD
Number of circuit poles	3 pole	Product Name	3 Extreme thermal overload relay
Tripping level	10A	Storage Temperature	-60°C ~ +70°C
Insulation voltage	690V	Operating temperature (no volume reduction)	-20°C ~ +60°C
Shock withstand voltage	6KV	Operating temperature (with capacity reduction)	-20°C ~ +60°C
Agreed heating current	5A	Temperature compensation	-20°C ~ +60°C
Seismic performance	6gn	Impact resistance	15gn~11ms
Phase deficiency sensitivity	The tripping current I is 30% of IR, and the other two phases are IR.
Installation method	Combined installation and independent installation with contactor.

Figure 7: Thermal Overload Relay Product Parameters

4.2 Model Selection Guide

Refer to the table below to select the appropriate LRD thermal overload relay model based on the current regulation range and adaptive contactor.

Product Model	Current regulation range	Adaptive contactor	Suitable base
LRD01C	0.1-0.16A	LC1D09-38	LAD7B106C
LRD02C	0.16-0.25A	LC1D09-38
LRD03C	0.25-0.4A	LC1D09-38
LRD04C	0.4-0.63A	LC1D09-38
LRD05C	0.63-1A	LC1D09-38
LRD06C	1-1.6A	LC1D09-38
LRD07C	1.6-2.5A	LC1D09-38
LRD08C	2.5-4A	LC1D09-38
LRD10C	4-6A	LC1D09-38
LRD12C	5.5-8A	LC1D09-38
LRD14C	7-10A	LC1D09-38
LRD16C	9-13A	LC1D12-38
LRD21C	12-18A	LC1D18-38
LRD22C	16-24A	LC1D25-38
LRD32C	23-32A	LC1D25-38
LRD35C	30-38A	LC1D32-38

Detailed reference table for thermal relay model selection, showing current regulation ranges, adaptive contactors, and suitable bases for LRD01C to LRD35C models. — Figure 8: Thermal Relay Model Selection Table

Table for selecting the matching contactor model for various LRD thermal overload relays. — Figure 9: Contactor Matching Table

5. Setup and Installation

The LRD thermal overload relay can be installed either combined with a contactor or as an independent unit. Always ensure power is disconnected before installation.

5.1 Wiring Instructions

Use crimp-type wiring and ensure all screws are securely fastened.
Connect the main power lines to the T1, T2, T3 connection ports.
Auxiliary contacts (97 NO, 98 NO, 95 NC, 96 NC) can be used for control circuits, such as signaling or interlocking.

5.2 Contactor Compatibility

TeSys series contactors and TeSys series thermal relays are designed for direct plug-in compatibility. However, this relay cannot be directly plugged in with other series of thermal relays. Refer to the model selection guide (Figure 8 and Figure 9) to ensure compatibility with your contactor.

5.3 Packaging and Certification

Image showing the independent packaging and Certificate of Conformity for the LRD thermal overload relay. — Figure 10: Product Packaging and Certificate of Conformity

6. Operation

6.1 Setting Current

Use the current setting dial on the front of the relay to adjust the desired current protection range. Ensure the setting matches the motor's rated current to provide optimal overload protection.

6.2 Resetting the Relay

In case of an overload trip, the tripping indication will activate. After resolving the overload condition, press the blue RESET button to reset the relay and restore operation.

6.3 Manual Stop

The red STOP button can be used to manually stop the circuit controlled by the relay.

7. Maintenance

Regular inspection of the thermal overload relay is recommended to ensure optimal performance and safety. Check for any signs of physical damage, loose connections, or excessive heat. Keep the relay free from dust and debris. No specific user-serviceable parts are inside; refer to qualified personnel for any repairs.

8. Troubleshooting

If the relay trips frequently, investigate the cause of the overload. Common causes include:

Motor overload due to mechanical issues or excessive load.
Incorrect current setting on the relay.
Phase imbalance or loss.
Faulty motor or wiring.

Ensure the current setting is appropriate for the motor and that all connections are secure. If the issue persists, consult a qualified electrician.

9. User Tips

Always verify the current rating of your motor and select an LRD relay with a compatible current regulation range.
Ensure proper ventilation around the relay to prevent overheating, especially in enclosed panels.
For critical applications, consider periodic testing of the trip function to confirm relay responsiveness.

10. Video Overview

Watch this video for a visual demonstration of the Schneider Electric LRD21C thermal overload relay's physical features and operation.

Video 1: Schneider Electric LRD21C Thermal Overload Relay Overview

11. Warranty and Support

For warranty information and technical support, please refer to the official Schneider Electric documentation or contact your authorized dealer. Keep your purchase records for any warranty claims.