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7.4.3 Motor Insulation
For motor cable lengths that are less than or equal to the
maximum cable length listed in
, use the motor insulation ratings shown in
. If a motor has lower insulation rating, Danfoss
recommends using a dU/dt or sine wave filter.
Nominal AC line voltage
Motor insulation
U
N
≤
420 V
Standard U
LL
=1300 V
420 V<U
N
≤ 500 V
Reinforced U
LL
=1600 V
500 V<U
N
≤ 600 V
Reinforced U
LL
=1800 V
600 V<U
N
≤ 690 V
Reinforced U
LL
=2000 V
Table 7.66 Motor Insulation Ratings
7.4.4 Motor Bearing Currents
All motors installed with FC 302 90 kW or higher power
adjustable frequency drives should have NDE (Non-Drive
End) insulated bearings installed to eliminate circulating
bearing currents. To minimize DE (Drive End) bearing and
shaft currents, ensure proper grounding of the adjustable
frequency drive, motor, driven machine, and motor to the
driven machine.
Here are some standard mitigation strategies:
•
Use an insulated bearing.
•
Follow proper installation procedures.
-
Ensure the motor and load motor are
aligned.
-
Follow the EMC Installation guideline.
-
Reinforce the PE so the high frequency
impedance is lower in the PE than the
input power leads.
-
Provide a good high-frequency
connection between the motor and the
adjustable frequency drive. Use a
shielded cable that has a 360°
connection in the motor and the
adjustable frequency drive.
-
Ensure the impedance from the
adjustable frequency drive to building
ground is lower that the grounding
impedance of the machine. This can be
difficult for pumps.
-
Make a direct ground connection
between the motor and load motor.
•
Lower the IGBT switching frequency.
•
Modify the inverter waveform, 60° AVM vs.
SFAVM.
•
Install a shaft grounding system or use an
isolating coupling.
•
Apply conductive lubrication.
•
Use minimum speed settings if possible.
•
Try to ensure that the line voltage is balanced to
ground. This can be difficult for IT, TT, TN-CS, or
Grounded leg systems.
•
Use a dU/dt or sine-wave filter.
7.5 Control Cables and Terminals
7.5.1 Access to Control Terminals
All terminals to the control cables are located underneath
the terminal cover on the front of the adjustable frequency
drive. Remove the terminal cover with a screwdriver.
7.5.2 Control Cable Routing
Tie down and route all control wires as shown in
and
. Remember to connect the
shields in a proper way to ensure optimum electrical
immunity.
Serial Communication Bus Connection
Connections are made to the relevant options on the
control card. For more detail, see the relevant serial
communication bus instruction. The cable must be tied
down and routed along with other control wires inside the
unit. See
through
Electrical Installation
Design Guide
222
Danfoss A/S © Rev. 2014-02-10 All rights reserved.
MG34S222
7
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Summary of Contents for VLT AutomationDrive FC 300
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