Galvanic Isolation (Pelv) - Danfoss VLT Decentral FCD 300 Operating Instructions Manual

VLT® Decentral FCD
4.3.2 Derating for Ambient Temperature
The ambient temperature (T ) is the maximum temperature allowed. The average (T
AMB,MAX
If the frequency converter operates at temperatures above 40 °C, a derating of the rated output current is necessary.
FCD 303-305 +10 °C
FCD 307 +5 °C
FCD 335 -5 °C

4.3.3 Galvanic Isolation (PELV)

PELV (Protective Extra Low Voltage) isolation is achieved by inserting galvanic isolators between the control circuits and circuits that are connected to
the mains 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 mains 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 galvanically 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 galvanically 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 mains 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 earth.
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.04.B8.02 - VLT is a registered Danfoss trademark
) measured over 24 hours, must be at least 5 °C lower.
AMB,AVG
4 All about FCD 300
4
93