Decentral Solutions
All About FCD
300
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Special conditions
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Galvonic isolation (PELV)
PELV (Protective Extra Low Voltage) isolation is
achieved by inserting galvonic isolators between the
control circuits and circuits that are connected to the AC
input potential. These separators are designed to meet
the requirements for increased separation by means
of having the necessary creepage and air clearance.
These requirements are described in standard EN 50
178. It is also a requirement that installation is carried
out as described in local/national PELV regulations.
All control terminals, terminals for serial communication
and relay terminals are safely separated from the
AC input potential, i.e. they comply with the PELV
requirements. Circuits that are connected to control
terminals 12, 18, 19, 20, 27, 29, 33, 42, 46, 50, 53,
55 and 60 are galvonically connected to one another.
If switch S100 is opened the potentials of the group
18, 19, 20, 27, 29, 33 are separated from all other
input/output. In that case terminal 12 cannot be used
for supply for the digital inputs on these terminals.
Serial communication connected to terminals 67 -
70 is galvonically isolated from the control terminals,
although this is only a functional isolation.
The relay contacts on terminals 1 - 3 are isolated
from the other control circuits with increased isolation,
i.e. PELV is observed for these, even though there
is AC input potential in the relay terminals.
The circuit elements described below form the safe
electric separation. They fulfill the requirements
for increased isolation and associated testing
pursuant to EN 50 178.
1. Transformer and optical separation in voltage supply.
2. Optical isolation between Basic Motor
Control and control card
3. Isolation between the control card and
the power part.
4. Relay contacts and terminals relating to other
circuits on the control card.
PELV isolation of the control card is guaranteed
under the following condition:
-
There may be max. 300 V between phase
and ground.
A motor thermistor connected to terminals 31a-31b
must be double isolated to obtain PELV. Danfoss
Bauer provides double isolated thermistors.
See also the section
Diagram
in the Design Guide.
MG.90.F2.22 - VLT is a registered Danfoss trademark
179
Содержание VLT Decentral FCD 300
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Страница 178: ...Decentral Solutions Dimensions of mounting brackets MG 90 F2 22 VLT is a registered Danfoss trademark 178 ...