Important notes
Motor protection
6
Basic unit wiring
6.2
6.2.2
L
6.2-2
EDS82EV903-1.0-11/2002
6.2.2 Motor protection
l Extensive protection against overload:
– By overcurrent relays or temperature monitoring
– We recommend PTC thermistors or thermal contacts to monitor the motor
temperature. (Lenze three-phase AC motors are all equipped with thermal
contacts (NC contacts)
– PTCs or thermal contacts can be connected to the controller.
l Only use motors, which insulation is suitable for inverter operation:
– Insulation resistance: min. û =1.5kV,min.du/dt=5kV/ms
– Lenze-three-phase AC motors are designed for inverter operation.
– If you want to use motors with an unknown insulation resistance, please
contact your motor supplier.
6.2.3 Mains types/mains conditions
Please observe the restrictions of each mains type!
Mains Operation of the controllers Notes
With earthed neutral
(TT/TN mains)
No restrictions Observe controller ratings
With isolated neutral
(IT mains)
Possible, if the controller is protected in the event of an
earth fault in the mains supply
• by suitable equipment for detecting an earth fault and
• the controller is disconnected directly from the mains
In the event of an earth fault
at the inverter output, safe
operation cannot be
guaranteed.
DC supply via
+U
DC
/-U
DC
Allowed if the DC voltage is symmetrical with PE Controller will be destroyed if
+U
DC
or -U
DC
-conductor are
earthed.
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