Specifications

2.10 Galvanic Isolation (PELV)
2.10.1 PELV - Protective Extra Low Voltage
PELV (Protective Extra Low Voltage) offers protection
through extra low voltage. To ensure protection against
electric shock, use a PELV electrical supply and install 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 grounded Delta leg above 400 V.)
Galvanic (ensured) isolation is obtained by fulfilling
requirements for higher isolation and 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 is shown in six locations. See
Illustration 2.28:
To maintain PELV, all connections made to the control
terminals must be PELV.
130BA056.10
1
3
254
6
ba
M
Illustration 2.28 Galvanic Isolation
1 Power supply (SMPS) including signal isolation of U
DC
,
indicating the intermediate current voltage
2 Gate drive that runs the IGBTs (trigger transformers/opto-
couplers)
3 Current transducers
4 Opto-coupler, brake module
5 Internal inrush, RFI, and temperature measurement circuits
6 Custom relays
a Functional Galvanic Isolation
b Functional Galvanic Isolation
Table 2.18 Legend to Illustration 2.28
The functional galvanic isolation is for the 24 V back-up
option and for the standard bus interface.
WARNING
Installation at high altitude:
380–480 V, enclosure A, B and C: At altitudes above 2
km, contact Danfoss regarding PELV.
380–480 V, enclosure D, E and F: At altitudes above 3
km, contact Danfoss regarding PELV.
525–690 V: At altitudes above 2 km, please contact
Danfoss regarding PELV.
WARNING
Touching the electrical parts could be fatal, even after
the equipment has been disconnected from mains.
Ensure that other voltage inputs, such as load sharing
(linkage of DC intermediate circuit), as well as the motor
connection for kinetic back-up, have been disocnnect.
Before touching any electrical parts, wait at least the
amount of time indicated in Table 2.1. Shorter time is
allowed only if indicated on the nameplate for the
specific unit.
2.11 Earth Leakage Current
Follow national and local codes regarding protective
earthing of equipment with a leakage current > 3,5 mA.
Frequency converter technology implies high frequency
switching at high power. This will generate a leakage
current in the earth connection. A fault current in the
frequency converter at the output power terminals might
contain a DC component, which can charge the filter
capacitors and cause a transient earth current.
The earth leakage current is made up of several contri-
butions and depends on various system configurations
including RFI filtering, screened motor cables, and
frequency converter power.
130BB955.11
a
b
Cable length [m]
Leakage current [mA]
Illustration 2.29 Cable Length and Power Size Influence on
Leakage Current. Pa > Pb.
Introduction VLT® HVAC Drive FC 102 Design Guide
44 MG16C102 - Rev. 2013-08-20
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