Galvanic Isolation (Pelv); Ground Leakage Current - Danfoss FC 300 Design Manual

FC 300 Design Guide

Galvanic Isolation (PELV)

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PELV offers protection by way of extra low voltage. Protection against electric shock is
ensured when the electrical supply is of the PELV type and the installation is made as
described in local/national regulations on PELV supplies.
All control terminals and relay terminals 01-03/04-06 comply with PELV (Protective Extra Low Voltage)
(Does not apply to 525-600 V units and at grounded Delta leg above 300 V).
Galvanic (ensured) isolation is obtained by fulfilling requirements for higher isolation and by providing the
relevant creepage/clearance distances. These requirements are described in the EN 61800-5-1 standard.
The components that make up the electrical isolation, as described below, also comply with the
requirements for higher isolation and the relevant test as described in EN 61800-5-1.
The PELV galvanic isolation can be shown in six locations (see illustration):
In order to maintain PELV all connections made to the control terminals must be PELV,
e.g. thermistor must be reinforced/double insulated.
Power supply (SMPS) incl. signal isolation of
1.
U , indicating the intermediate current voltage.
DC
Gate drive that runs the IGBTs (trigger
2.
transformers/opto-couplers).
Current transducers.
3.
Opto-coupler, brake module.
4.
Internal inrush, RFI, and temperature
5.
measurement circuits.
6. Custom relays.
The functional galvanic isolation (a and b on drawing) is for the 24 V backup option
and for the RS-485 standard bus interface.

Ground Leakage Current

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Warning:
Touching the electrical parts may be fatal - even after the equipment has
been disconnected from line power.
Also make sure that other voltage inputs have been disconnected, such as load sharing (linkage
of DC intermediate circuit), as well as the motor connection for kinetic backup.
Using VLT AutomationDrive FC 300: wait at least 15 minutes.
Shorter time is allowed only if indicated on the nameplate for the specific unit.
Introduction to FC 300
Galvanic isolation
MG.33.B6.22 - VLT is a registered Danfoss trademark
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