1. Introduction
This manual provides essential information for the safe and effective installation, operation, and maintenance of the Schneider Electric LR9F5371 Thermal Overload Relay. This device is designed to protect electric motors from damage due to overload conditions, phase unbalance, or phase loss by monitoring the current drawn by the motor.
The LR9F5371 is a Class 10 thermal relay, suitable for a current range of 132 to 220 Amps, ensuring reliable protection for industrial applications.
2. Safety Information
WARNING: Electrical shock hazard. Only qualified personnel should install, operate, or service this equipment. Disconnect all power before working on the relay or associated circuitry.
- Always follow local and national electrical codes.
- Ensure proper grounding of all equipment.
- Do not operate the relay if it is damaged.
- Verify correct wiring connections before applying power.
3. Product Overview
The Schneider Electric LR9F5371 Thermal Relay features a robust design for industrial environments. Below is an image highlighting key components of the relay.
Figure 1: Schneider Electric LR9F5371 Thermal Relay. The image displays the front view of the relay, featuring the green Schneider Electric logo, the "LR9 F" model designation, and "ELECTRONIC MOTOR PROTECTION CLASS 10" text. Visible controls include a blue current adjustment dial with settings like 30, 35.5, 42.5, and 50. To the right, there are red "STOP" and blue "RESET" buttons, along with a "TEST" button. Terminal markings such as "NO 98 97" and "NC 95 96" are also clearly visible.
Key Components:
- Current Adjustment Dial: Used to set the nominal current for motor protection (e.g., 30A, 35.5A, 42.5A, 50A as indicated on the dial). The overall range for this model is 132-220 Amps.
- TEST Button: Simulates an overload condition to verify the relay's tripping function.
- STOP Button: Manually trips the relay.
- RESET Button: Resets the relay after an overload trip.
- Terminals: Screw terminals for connecting power and control circuits (e.g., NO 98-97, NC 95-96).
4. Setup and Installation
The LR9F5371 thermal relay is designed for DIN Rail mounting and utilizes screw-type connectors for secure wiring.
4.1 Mounting
- Ensure the mounting surface is stable and free from excessive vibration.
- Mount the relay securely onto a standard DIN rail.
- Allow adequate clearance around the relay for ventilation and wiring access.
4.2 Wiring
Refer to the motor and control circuit diagrams for specific wiring requirements. The relay's main power terminals are designed to handle currents up to 220 Amps, while the control contacts (NO/NC) are for signaling purposes.
- Connect the main power circuit through the relay's power terminals.
- Connect the Normally Open (NO) contacts (97-98) to the motor starter coil circuit to allow motor operation when the relay is not tripped.
- Connect the Normally Closed (NC) contacts (95-96) to a fault indicator or control circuit to signal an overload condition.
- Ensure all screw terminals are tightened to the recommended torque to prevent loose connections and overheating.
5. Operating Instructions
5.1 Setting the Current
Rotate the current adjustment dial to set the desired motor full-load current (FLC). This setting should match the motor's nameplate FLC or be slightly above it, within the relay's operating range of 132-220 Amps. The dial provides fine adjustment within specific sub-ranges (e.g., 30-50 on the visible scale, which represents a specific range within the overall 132-220A capability of the LR9F5371 model).
5.2 Testing the Relay
To verify the relay's functionality, press the TEST button. This action should trip the relay, opening the NO contacts and closing the NC contacts, simulating an overload. The motor starter should de-energize, stopping the motor.
5.3 Resetting the Relay
After an overload trip, allow the motor and relay to cool down. Once cooled, press the RESET button to restore the relay to its normal operating state. If the relay trips repeatedly, investigate the cause of the overload.
5.4 Manual Stop
The STOP button can be pressed to manually trip the relay, similar to an overload condition, which will de-energize the motor starter.
6. Maintenance
The Schneider Electric LR9F5371 Thermal Relay is designed for minimal maintenance. However, periodic checks are recommended to ensure optimal performance and longevity.
- Visual Inspection: Regularly inspect the relay for any signs of physical damage, discoloration due to overheating, or loose connections.
- Cleaning: Keep the relay free from dust and debris. Use a dry, soft cloth for cleaning. Do not use solvents or abrasive cleaners.
- Functionality Test: Periodically perform the TEST button function to ensure the tripping mechanism is operational.
7. Troubleshooting
This section addresses common issues you might encounter with the LR9F5371 Thermal Relay.
| Problem | Possible Cause | Solution |
|---|---|---|
| Relay trips frequently. | Motor overload, incorrect current setting, phase imbalance, motor fault. | Verify motor load, check motor nameplate FLC and adjust relay setting, inspect motor and power supply for issues. |
| Relay does not reset. | Still in overload condition, relay not cooled down, internal fault. | Allow sufficient cooling time, ensure overload condition is resolved. If issue persists, relay may need replacement. |
| Motor does not start. | Relay tripped, control circuit wiring error, power supply issue. | Check if relay is tripped and reset if necessary. Verify control circuit wiring, especially NO contacts (97-98). Check power supply to motor and starter. |
8. Specifications
| Attribute | Value |
|---|---|
| Model Number | LR9F5371 |
| Brand | Schneider Electric Telemecanique |
| Description | Thermal Overload Relay |
| Current Range | 132 - 220 Amps (Class 10) |
| Nominal Current Rating | 132 Amps (Adjustable within range) |
| Contact Type | Normally Open (NO), Normally Closed (NC) |
| Contact Material | Silver |
| Connector Type | Screw |
| Mounting Type | DIN Rail Mount |
| Product Dimensions | 5.12 x 6.5 x 5.91 inches |
| Product Weight | 2.28 Pounds |
| Date First Available | March 13, 2014 |
9. Warranty and Support
For information regarding warranty, technical support, or service, please contact Schneider Electric directly or visit their official website. Always refer to the original purchase documentation for specific warranty terms and conditions.
You can find more information about Schneider Electric products and support at their official store: Schneider Electric Store
