The common of digital / analog inputs and outputs should be connected to separate common terminals 20, 39, and 55. This will avoid ground current interference

among groups. For example, it avoids switching on digital inputs disturbing analog inputs.

NB!

Control cables must be screened/armoured.

4.2.3 Motor Cables

See section General Specifications for maximum dimensioning of motor cable cross-section and length.

•

Use a screened/armoured motor cable to comply with EMC emission specifications.

•

Keep the motor cable as short as possible to reduce the noise level and leakage currents.

•

Connect the motor cable screen to both the de-coupling plate of the frequency converter and to the metal cabinet of the motor.

•

Make the screen connections with the largest possible surface area (cable clamp). This is done by using the supplied installation devices in the frequency

converter.

•

Avoid mounting with twisted screen ends (pigtails), which will spoil high frequency screening effects.

•

If it is necessary to split the screen to install a motor isolator or motor relay, the screen must be continued with the lowest possible HF impedance.

Unit Size 6X Requirements

Unit Size 61/63 requirements: Motor phase cable quantities must be multiples of 2, resulting in 2, 4, 6, or 8 (1 cable is not allowed) to obtain equal amount of

wires attached to both inverter module terminals. The cables are required to be equal length within 10% between the inverter module terminals and the first

common point of a phase. The recommended common point is the motor terminals.

Unit Size 62 and 64 requirements: Motor phase cable quantities must be multiples of 3, resulting in 3, 6, 9, or 12 (1 or 2 cables are not allowed) to obtain equal

amount of wires attached to each inverter module terminal. The wires are required to be equal length within 10% between the inverter module terminals and the

first common point of a phase. The recommended common point is the motor terminals.

Output junction box requirements: The length, minimum 2.5 meters, and quantity of cables must be equal from each inverter module to the common terminal

in the junction box.

4.2.4 Electrical Installation of Motor Cables

Screening of cables

Avoid installation with twisted screen ends (pigtails). They spoil the screening effect at higher frequencies.

If it is necessary to break the screen to install a motor isolator or motor contactor, the screen must be continued at the lowest possible HF impedance.

Cable length and cross-section

The frequency converter has been tested with a given length of cable and a given cross-section of that cable. If the cross-section is increased, the cable capacitance

- and thus the leakage current - may increase, and the cable length must be reduced correspondingly.

Switching frequency

When frequency converters are used together with Sine-wave filters to reduce the acoustic noise from a motor, the switching frequency must be set according

to the Sine-wave filter instruction in par. F-26 Motor Noise (Carrier Freq).

Aluminium conductors

Aluminium conductors are not recommended. Terminals can accept aluminium conductors but the conductor surface has to be clean and the oxidation must be

removed and sealed by neutral acid free Vaseline grease before the conductor is connected.

Furthermore, the terminal screw must be retightened after two days due to the softness of the aluminium. It is crucial to keep the connection a gas tight joint,

otherwise the aluminium surface will oxidize again.

AF-600 FP Design Guide

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