Introduction
This manual provides essential information for the safe and efficient operation of the Danfoss VLT Micro Drive FC-51. The VLT Micro Drive is a general-purpose frequency converter designed to control AC motors up to 22.0 kW. It is engineered for reliability and environmental compliance, adhering to the RoHS Directive.
Safety Information
Always read and understand all safety instructions before installing, operating, or maintaining the drive. Failure to follow these instructions can result in serious injury or equipment damage.
- Disconnect power before servicing. Ensure the main power supply is completely off and locked out before performing any work on the drive.
- Ensure proper grounding. The drive must be correctly grounded according to local and national electrical codes to prevent electrical shock.
- Installation and maintenance should only be performed by qualified personnel. Only trained and authorized individuals should handle the installation, wiring, and maintenance of this equipment.
- Protect against accidental startup. Implement measures to prevent unintended motor startup during maintenance or troubleshooting.
- Observe all local and national electrical codes. Adhere to all applicable regulations and standards for electrical installations.
Product Overview
The Danfoss VLT Micro Drive FC-51 is a compact and robust frequency converter designed for a wide range of industrial applications.
Components and Controls

The control panel provides access to various functions and settings:
- Menu Buttons: 'Menu', 'Status', 'Quick Menu', 'Main Menu' for navigating through settings and information displays.
- Navigation/Selection: 'Back' button, 'OK' button, and directional arrows for parameter adjustment and confirmation.
- Status Indicators: 'On', 'Warn', 'Alarm' LEDs to indicate operational status and alert conditions.
- Operation Modes: 'Hand On' for manual control, 'Off Reset' to stop the motor and reset errors, and 'Auto On' for automatic operation based on external commands.
Setup
Proper setup is crucial for optimal performance and safety of the VLT Micro Drive.
Mounting
Mount the drive vertically on a flat, non-combustible surface, ensuring adequate clearance for ventilation. Refer to the mounting dimensions in the specifications section for precise requirements. Ensure the ambient temperature is within the specified operating range.
Wiring
Connect the main power supply, motor, and control signals according to the detailed wiring diagrams provided in the full product manual (not included here). Ensure all connections are secure, correctly phased, and comply with all electrical safety standards. Use appropriate cable sizes and protection devices.
Initial Power-Up
After completing all wiring and safety checks, apply power to the drive. The display should illuminate. Follow the initial setup wizard (if applicable) to configure basic parameters such as motor data, application type, and desired control mode. This step is critical for the drive to operate correctly with your specific motor and application.
Operating the Drive
The VLT Micro Drive FC-51 offers various operating modes to suit different application needs.
Manual Operation
To enable manual control, press the 'Hand On' button. Once in manual mode, use the navigation buttons (up/down arrows) to adjust the output frequency or motor speed directly from the control panel. This mode is useful for testing or specific manual adjustments.
Automatic Operation
Press the 'Auto On' button to enable automatic control. In this mode, the drive responds to external signals, such as those from a PLC (Programmable Logic Controller), analog inputs, or fieldbus commands. This is the typical mode for integrated system operation.
Monitoring
Use the 'Status' or 'Quick Menu' buttons to view real-time operational data. This includes output frequency, motor current, motor voltage, DC link voltage, and other critical parameters. Regular monitoring helps in understanding the drive's performance and identifying potential issues early.
Maintenance
Regular maintenance ensures the longevity and reliable operation of your Danfoss VLT Micro Drive.
- Cleaning: Periodically clean the heat sink fins and ventilation openings to prevent dust accumulation. Dust can impede cooling and lead to overheating. Use compressed air or a soft brush for cleaning. Ensure power is disconnected before cleaning.
- Inspection: Routinely inspect all wiring connections for tightness and signs of wear, corrosion, or damage. Loose connections can cause intermittent operation or overheating. Check for any unusual noises or odors during operation, which may indicate an internal issue.
- Environmental Conditions: Ensure the operating environment remains within the specified temperature and humidity ranges. Extreme conditions can shorten the lifespan of the drive's components. Protect the drive from excessive vibration and corrosive atmospheres.
Troubleshooting
This section provides guidance for common issues you might encounter. For detailed troubleshooting, including specific fault codes, refer to the comprehensive product manual.
| Problem | Possible Cause | Solution |
|---|---|---|
| Drive does not power on | No input power; Blown fuse; Internal fault | Check power supply and circuit breaker; Replace fuses; Contact service if internal fault suspected |
| Motor not running | Incorrect wiring; Parameter error; External stop command | Verify motor and control wiring; Check motor parameters (e.g., frequency, voltage); Ensure no active stop commands |
| Overcurrent fault | Motor overload; Short circuit in motor or cables; Rapid acceleration | Reduce mechanical load; Check motor and cables for shorts; Increase acceleration ramp time |
| Overvoltage fault | High input voltage; Regenerative braking from motor; Long motor cables | Check input voltage stability; Install braking resistor if needed; Consider output filter for long cables |
| Overheat fault | Insufficient ventilation; High ambient temperature; Clogged heat sink | Ensure proper airflow; Reduce ambient temperature; Clean heat sink fins |
Technical Specifications
| Feature | Detail |
|---|---|
| Model | VLT Micro Drive FC-51 (FC-051P7K5T4E20H3BXCXXXSXXX) |
| Power Rating | 7.5 KW / 10 HP |
| Input Voltage | Three phase 380 - 480 VAC |
| Enclosure Rating | IP20 / Chassis (E20) |
| RFI Filter | Class A1/B (C1) |
| Brake Chopper | Included |
| Coated PCB | Yes |
| Product Dimensions | 8.09 x 3.54 x 9.41 inches |
| Item Weight | 2.2 pounds |
| Manufacturer | Danfoss |
| Date First Available | August 30, 2022 |
Warranty and Support
For detailed warranty information and technical support, please contact Danfoss customer service or visit the official Danfoss website. Keep your purchase receipt and product model number readily available for any inquiries. Danfoss is committed to providing comprehensive support for its products.
For additional resources, complete product manuals, and the latest software updates, visit the official Danfoss website:





