Galvanic Isolation (Pelv) - Danfoss VLT AQUA Drive Design Manual

VLT ® AQUA Drive Design Guide

2.11. Galvanic isolation (PELV)

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 pro-
viding 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. For ex-
ample, the thermistor must be reinforced/double insulated.
1.
2.
3.
4.
5.
6.
The functional galvanic isolation (a and b in drawing) is for the 24 V backup option and for the
RS-485 standard bus interface.
Power supply (SMPS) incl. signal iso-
lation of U , indicating the inter-
DC
mediate current voltage.
Gate drive that runs the IGBTs (trig-
ger transformers/opto-couplers).
Current transducers.
Opto-coupler, brake module.
Internal soft-charge, RFI and tem-
perature measurement circuits.
Custom relays.
At altitudes higher than 6,600 feet [2 km], please contact Danfoss Drives regarding
PELV.
MG.20.N2.22 - VLT ® is a registered Danfoss trademark.
2. Introduction to the VLT AQUA Drive
2.2: Galvanic isolation
2
35