Danfoss VLT® Advanced Harmonic Filter AHF 005/AHF 010 Design Guide

Quick guide from the manual

This design guide provides essential information for the installation, operation, and maintenance of the Danfoss VLT® Advanced Harmonic Filters AHF 005 and AHF 010. These filters are designed to mitigate harmonic distortion in electrical systems using VLT® frequency converters. Important: Only qualified personnel are permitted to install, commission, and maintain this equipment. Always observe safety precautions, including waiting for capacitors to discharge before performing any service.

Operating Principle

The AHF 005 and AHF 010 filters consist of a main inductor and a 2-stage absorption circuit. They are tuned to eliminate harmonics starting from the 5th harmonic. The AHF 005 provides 5% THDi performance, while the AHF 010 provides 10% THDi performance. Performance varies based on load; at part load, THDi may be higher, but the absolute harmonic current is lower.

Installation Requirements

Mechanical Mounting

• Mount filters vertically with terminals at the bottom.
• Ensure top and bottom clearances of at least 150 mm.
• Do not mount near heat-sensitive materials or other heating elements.
• Use dedicated lifting eyes for installation.
• For rail-mounted installations, use a backplate to prevent false airflow.

Electrical Installation

• Connect mains supply to terminals X1.1–X1.3.
• Connect drive supply to terminals X2.1–X2.3.
• Optional capacitor disconnect terminals are X3.1–X3.3 and X4.1–X4.3.
• Use shielded cables for control wiring to avoid high-frequency noise coupling.

Overtemperature Protection

The filters are equipped with thermal switches. If the filter overheats (above 140 °C), the switch opens. It is mandatory to use this switch to prevent damage. Program the frequency converter to perform an immediate stop or controlled ramp down within 30 seconds if the switch activates.

Programming

Parameters are available to configure digital inputs and outputs for filter operation, including overtemperature protection and capacitor disconnect control. Refer to the specific parameter groups (5-0*, 5-1*, 5-3*) for detailed settings.

Specifications

The filters are designed for various voltage classes (380–690 V) and frequencies (50/60 Hz). They feature an overload capacity of 160% for 60 seconds every 10 minutes. Detailed power loss and acoustic noise data are provided in the guide for each filter size and load percentage.

Spare Parts

Spare parts are revision-specific. Always check the revision number on the product label (characters 5 and 6 of the serial number) before ordering kits, including capacitor kits, terminal kits, fan kits, and fuse kits.