3 Installation
3.4 Earthing
DC1 variable frequency drive 12/13 MN04020003Z-EN www.eaton.com 57
3.4.1 Protective earth
This refers to the legally required protective earth for a variable frequency
drive. An earthing terminal on the variable frequency drive, or the system
earth, must be connected to a neighboring steel element in the building
(beam, ceiling joist), an earth electrode in the ground, or a mains earth bus.
The earth points must meet the requirements set forth by the applicable
national and local industrial safety regulations and/or regulations for electrical
systems.
3.4.2 Motor earthing
The motor earth must be connected to one of the earthing terminals on the
variable frequency drive and to a neighboring steel element in the building
(beam, ceiling joist), an earth electrode in the ground, or a mains earth bus.
3.4.3 Earth-fault protection
A fault current to earth can be produced by variable frequency drives due to
their system characteristics. DC1 series variable frequency drives have been
designed in such a way that the smallest possible fault current will be
produced in compliance with standards applicable worldwide. This fault
current must be monitored by a residual current device (RCD, type B).
3.4.4 VAR screw
DC1 series variable frequency drives are equipped with an overvoltage filter
for the input supply voltage that is designed to protect the devices from
noise pulses in the mains voltage. Pulse spikes are typically caused by light-
ning strikes or by switching operations in other high-power devices on the
same supply.
If high potential tests are performed on a system, these overvoltage
protection components may cause the system to fail the test. In order to
make it possible to perform this type of hipot tests, the overvoltage
protection components can be disconnected by removing the VAR screw
(in DC1-…-A20N models only). The screw must be screwed back in after the
high potential tests are performed and the test must then be repeated. The
system must then fail the test, indicating that the overvoltage protection
components have been reconnected.
NOTICE
The screw labeled VAR ( Figure 33, page 55) must not be
manipulated as long as the variable frequency drive is
connected to the mains.
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