24 V external DC supply can be used as low-voltage supply to the control card and any option cards installed. This enables full operation of the LCP (incl.

parameter setting) without connection to mains. Please note that a warning of low voltage will be given when 24 V DC has been connected; however,

there will be no tripping.

Use 24 V DC supply of type PELV to ensure correct galvanic isolation (type PELV) on the control terminals of the frequency converter.

6.5.2. Power Connections

Cabling and Fusing

NB!

Cables General

All cabling must comply with national and local regulations on cable cross-sections and ambient temperature. Copper (75°C) conductors

are recommended.

The power cable connections are situated as shown below. Dimensioning of cable cross section must be done in accordance with the current ratings and

local legislation. See the

For protection of the frequency converter the recommended fuses must be used or the unit must be with built-in fuses. Recommended fuses can be seen

in the tables in the fuses section. Always ensure that proper fusing is made according to local regulation.

The mains connection is fitted to the mains switch if this is included.

NB!

Motor cable must be screened/armoured. If an

unscreened/unarmoured cable is used, some EMC re-

quirements are not complied with. Use a screened/

armoured motor cable to comply with EMC emission

specifications. For more information, see

cations

See section

General Specifications

Screening of cables:

Avoid installation with twisted screen ends (pigtails). They spoil the screening effect at higher frequencies. If it is necessary to break the screen to install

a motor isolator or motor contactor, the screen must be continued at the lowest possible HF impedance.

Connect the motor cable screen to both the de-coupling plate of the frequency converter and to the metal housing of the motor.

Make the screen connections with the largest possible surface area (cable clamp). This is done by using the supplied installation devices in the frequency

converter.

114

Specifications section

for details.

EMC specifi-

Design Guide

in the

for correct dimensioning of motor cable cross-section and length.

MG.33.BA.02 - VLT

is a registered Danfoss trademark

FC 300 Design Guide

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