Motor Insulation; Motor Bearing Currents; Control Cables And Terminals; Access To Control Terminals - Danfoss VLT AutomationDrive FC 300 Design Manual

Electrical Installation

7.4.3 Motor Insulation

For motor cable lengths that are less than or equal to the
maximum cable length listed in 4.3 General Specifications,
use the motor insulation ratings shown in Table 7.66. If a
motor has lower insulation rating, Danfoss recommends
using a dU/dt or sine wave filter.
Nominal mains voltage
≤420 V
U
N
420 V<U ≤ 500 V
N
500 V<U ≤ 600 V
N
600 V<U ≤ 690 V
N
Table 7.66 Motor Insulation Ratings

7.4.4 Motor Bearing Currents

7 7
All motors installed with FC 302 90 kW or higher power
frequency converters 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 frequency
converter, motor, driven machine, and motor to the driven
machine.
Here are some standard mitigation strategies:
•
Use an insulated bearing.
•
Follow proper installation procedures.
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-
-
-
-
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•
Lower the IGBT switching frequency.
•
Modify the inverter waveform, 60° AVM vs.
SFAVM.
200
VLT
Motor insulation
Standard U =1300 V
LL
Reinforced U =1600 V
LL
Reinforced U =1800 V
LL
Reinforced U =2000 V
LL
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
frequency converter. Use a screened
cable that has a 360° connection in the
motor and the frequency converter.
Ensure the impedance from the
frequency converter to building ground
is lower that the grounding impedance
of the machine. This can be difficult for
pumps.
Make a direct earth connection between
the motor and load motor.
®
AutomationDrive FC 300 Design Guide 90-1200 kW
•
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 frequency converter.
Remove the terminal cover with a screw driver.

7.5.2 Control Cable Routing

Tie down and route all control wires as shown in
Illustration 7.35 and Illustration 7.36. Remember to connect
the shields in a proper way to ensure optimum electrical
immunity.
Fieldbus Connection
Connections are made to the relevant options on the
control card. For more detail, see the relevant fieldbus
instruction. The cable must be tied down and routed along
with other control wires inside the unit. See Illustration 7.35
through Illustration 7.39.
Illustration 7.35 Control Card Wiring Path for the D3h. Control
Card Wiring for the D1h, D2h, D4h, E1 and E2 Use the Same
Path
MG34S202 - Rev. 2013-08-19