1. Introduction
This instruction manual provides essential information for the safe and effective installation, operation, and maintenance of the Schneider Electric TeSys LRD22 Thermal Overload Relay. Please read this manual thoroughly before attempting any installation or operation to ensure proper function and prevent potential hazards.
2. Safety Information
WARNING: Risk of Electric Shock or Explosion.
- Only qualified personnel should install, operate, service, and maintain this equipment.
- Disconnect all power before working on equipment.
- Always use a properly rated voltage sensing device to confirm power is off.
- Replace all devices, doors, and covers before applying power.
- Failure to follow these instructions will result in death or serious injury.
Observe all local and national electrical codes and regulations.
3. Product Overview
The Schneider Electric TeSys LRD22 is a thermal overload relay designed to protect AC circuits and motors against overloads, phase failure, and long starting times. It is a Class 10A relay, suitable for applications requiring rapid tripping in case of an overload. The relay features an adjustable current setting and manual reset/stop functions.
Figure 1: TeSys LRD22 Overload Relay Front View
This image displays the front panel of the Schneider Electric TeSys LRD22 Overload Relay. Visible features include the 'TeSys' and 'Schneider Electric' branding, the 'LRD22' model designation, an adjustable current setting dial ranging from 16 to 24 Amperes, and 'RESET' (blue button) and 'STOP' (red button) controls. The bottom section shows terminal markings such as '97 NO', '98 NO', '95 NC', and '96 NC'. The top features three copper connection pins.
Key Features:
- Thermal overload protection.
- Phase failure sensitivity.
- Adjustable current setting (16-24 A).
- Manual reset and stop functions.
- Direct mounting under contactors or stand-alone mounting.
4. Installation and Setup
4.1 Mounting
The LRD22 relay can be mounted directly to a compatible contactor or installed as a stand-alone unit using appropriate accessories (sold separately). Ensure secure mounting to prevent vibration and movement.
4.2 Wiring
- Ensure all power is disconnected before wiring.
- Connect the main power circuit through the relay's power terminals (L1, L2, L3 to T1, T2, T3). The copper pins visible on the top of the relay are for connection to the contactor.
- Connect the control circuit to the auxiliary contacts:
- 97 NO / 98 NO: Normally Open auxiliary contacts, typically used for signaling an overload condition.
- 95 NC / 96 NC: Normally Closed auxiliary contacts, typically used to interrupt the contactor coil circuit upon an overload.
- Ensure all connections are tight and secure.
4.3 Current Setting
Adjust the current setting dial (visible on the front panel, ranging from 16 to 24 A) to match the motor's full load current (FLC) as specified on the motor's nameplate. Setting the current too high will reduce protection; setting it too low may cause nuisance tripping.
5. Operation
5.1 Normal Operation
Once correctly installed and set, the LRD22 relay continuously monitors the motor current. In normal operating conditions, the relay allows the motor to run without interruption.
5.2 Overload Tripping
If an overload condition occurs (current exceeds the set value for a sustained period) or a phase failure is detected, the relay will trip. When tripped, the normally closed contacts (95-96) will open, and the normally open contacts (97-98) will close, signaling the overload and typically stopping the motor.
5.3 Resetting the Relay
After an overload trip, allow the motor and relay to cool down. To reset the relay, press the blue "RESET" button on the front panel. Ensure the cause of the overload has been identified and rectified before resetting and restarting the motor.
5.4 Stop Function
The red "STOP" button on the front panel can be used to manually trip the relay, interrupting the motor circuit. This is useful for testing or emergency shutdown procedures. After pressing "STOP", the relay must be reset using the blue "RESET" button to resume operation.
6. Maintenance
The TeSys LRD22 overload relay is designed for minimal maintenance. Regular inspection is recommended:
- Visual Inspection: Periodically check for any signs of physical damage, discoloration, 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 Check: Periodically test the "STOP" and "RESET" functions to ensure they operate correctly.
7. Troubleshooting
| Problem | Possible Cause | Solution |
|---|---|---|
| Relay trips frequently. |
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| Relay does not trip on overload. |
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| Relay cannot be reset. |
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8. Specifications
| Feature | Detail |
|---|---|
| Model | LRD22 |
| Type | Thermal Overload Relay |
| Current Adjustment Range | 16 - 24 Amperes |
| Tripping Class | Class 10A |
| Material | Copper (for main contacts/pins) |
| Item Weight | 5.1 ounces (approx. 145 grams) |
| Package Dimensions | 3.78 x 3.11 x 1.85 inches (9.6 x 7.9 x 4.7 cm) |
| Manufacturer | Schneider Electric (listed as Kempston Controls in some specifications, but product is branded Schneider Electric) |
9. Warranty Information
For detailed warranty information regarding your Schneider Electric TeSys LRD22 Overload Relay, please refer to the official Schneider Electric website or contact their customer support. Warranty terms and conditions may vary by region and purchase date.
10. Support and Contact
If you require technical assistance, have questions about installation, or need to report an issue, please contact Schneider Electric customer support:
- Website: Visit the official Schneider Electric website for support resources, FAQs, and contact details.
- Local Support: Refer to your regional Schneider Electric contact information for localized assistance.
