Galvanic Isolation (Pelv); Pelv - Protective Extra Low Voltage; Earth Leakage Current - Danfoss VLT AQUA Design Manual

2. Introduction to VLT AQUA Drive

2.11. Galvanic isolation (PELV)

2.11.1. PELV - Protective Extra Low Voltage

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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 creapage/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.
1. Power supply (SMPS) incl. signal isolation of U
intermediate current voltage.
2. Gate drive that runs the IGBTs (trigger transformers/opto-cou-
plers).
3. Current transducers.
4. Opto-coupler, brake module.
5. Internal inrush, RFI, and temperature measurement circuits.
6. Custom relays.
The functional galvanic isolation (a and b on drawing) is for the 24 V back-up option and for the RS 485 standard bus interface.
Installation at high altitude
380 - 500 V: At altitudes above 3 km, please contact Danfoss Drives regarding PELV.
525 - 690 V: At altitudes above 2 km, please contact Danfoss Drives regarding PELV.

2.12. Earth leakage current

Warning:
Touching the electrical parts may be fatal - even after the equipment has been disconnected from mains.
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 back-up.
Before touching any electrical parts, wait at least: Please consult the section
Shorter time than stated in the table is allowed only if indicated on the nameplate for the specific unit.
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, indicating the
DC
Illustration 2.4: Galvanic isolation
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MG.20.N3.02 - VLT is a registered Danfoss trademark
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VLT AQUA Drive Design Guide
Safety Caution
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