Motor Connection - Danfoss VLT Micro Drive PK18 Design Manual

How to Install

6.8 Motor Connection

6.8.1 How to Connect the Motor
See 9 Specifications for correct dimensioning of motor
cable cross-section and length.
•
Use a shielded/armored motor cable to comply
with EMC emission specifications, and connect
this cable to both the decoupling plate and the
motor metal.
•
Keep motor cable as short as possible to reduce
the noise level and leakage currents.
For further details on mounting of the decoupling plate,
please see instruction MI.02.BX.YY.
All types of three-phased asynchronous standard motors
can be connected to the frequency converter. Normally,
small motors are star-connected (230/400 V, Δ/Y). Large
motors are delta-connected (400/690 V, Δ/Y). Refer to
motor nameplate for correct connection and voltage.
Illustration 6.6 Star and delta connections.
Step 1: First, mount the earth cable.
Step 2: Connect wires to terminals either in star or delta-
connection. See motor nameplate for further information.
Illustration 6.7 Mounting of earth cable and motor wires.
For EMC correct installation, use optional de-coupling
plate, see chapter 5.2 Options for VLT Micro Drive.
VLT Micro Drive Design Guide
Illustration 6.8 Frequency converter with de-coupling plate
6.8.2 Motor Cables
See 9 Specifications for maximum dimensioning of motor
cable cross-section and length.
6.8.3 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.
®
MG02K102 - VLT is a registered Danfoss trademark
•
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.
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