3 Installation
3.5 EMC installation
DA1 Variable Frequency Drives
08/18 MN04020005Z-EN
www.eaton.com
95
3.5.4 VAR screw
DA1 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
lightning strikes or by switching operations in other high-power devices on
the same supply.
If high-voltage 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 high-voltage tests, the overvoltage
protection components can be disconnected by removing the VAR screw.
The screw must be screwed back in after the high-voltage 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.
3.5.5 Shielding
Cables that are not screened work like antennas (sending, receiving).
The effectiveness of the cable screen depends on a good screen connection
and a low screen impedance.
￫
The VAR screw is found only in devices in sizes FS2 and FS3
with IP20 protection.
WARNING
The screw labeled VAR (
gure 58, page 94) must not be
adjusted as long as the variable frequency drive is connected to
the mains.
￫
For a proper EMC connection, cables emitting interference
(e. g., motor cables) and susceptible cables (analog signal and
measured values) must be screened and laid separately from
each other.
￫
Use only screens with tinned or nickel-plated copper braiding.
Braided steel shields are unsuitable.
￫
Control and signal lines (analog, digital) should always be
grounded on one end, in the immediate vicinity of the supply
voltage source (PES).
