Danfoss VLT AQUA Drive - How to Connect Motor

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5.1.8. Mains connection for C1 and C2

Illustration 5.11: How to connect to mains and earthing.

5.1.9. How to connect motor - foreword

See section

General Specifications

for correct dimensioning of motor cable cross-section and length.

• Use a screened/armoured motor cable to comply with EMC emission specifications (or install the cable in metal conduit).

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

• Connect the motor cable screen/armour to both the decoupling plate of the frequency converter and to the metal of the motor. (Same applies

to both ends of metal conduit if used instead of screen.)

• Make the screen connections with the largest possible surface area (cable clamp or by using an EMC cable gland). This is done by using the

supplied installation devices in the frequency converter.

• Avoid terminating the screen by twisting the ends (pigtails), as this will spoil high frequency screening effects.

• If it is necessary to break the continuity of the screen to install a motor isolator or motor relay, the continuity must be maintained with 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. 14-01.

Precautions while using Aluminium conductors

Aluminium conductors are not recommended for cable cross sections below 35 mm². 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 ensure the connection makes

a gas tight joint, otherwise the aluminium surface will oxidize again.

VLT

AQUA Drive

Operating Instructions