3.3.3 Screened/Armoured Cables
The screen must have low HF impedance, which is achieved by a braided screen of copper, aluminium or iron. Screen reinforcement intended for
mechanical protection, for example, is not suitable for EMC-correct installation. See also
Use of EMC-Correct Cables
.
3.3.4 Extra Protection
ELCB relays, multiple protective earthing or earthing can be used as extra protection, provided that local safety regulations are complied with. In the case
of an earth fault, a DC content may develop in the faulty current. Never use an RCD (ELCB relay), type A, as it is not suitable for DC faulty currents. If
ELCB relays are used, local regulations must be complied with.If ELCB relays are used, they must be:
-
Suitable for protecting equipment with a DC content in the faulty current (3-phase bridge rectifier)
-
Suitable for a pulse-shaped, brief discharge on power-up
-
Suitable for a high leakage current.
See also RCD Application Note MN.90.GX.02.
3.3.5 High Voltage Test
A high voltage test can be performed by short-circuiting terminals U, V, W, L1, L2 and L3, and applying max. 2160 V DC in 1 sec. between this short-
circuit and PE-terminal.
3.3.6 Electronics Purchased without Installation Box
If the electronic part is purchased without the Danfoss installation part, the earth connection must be suitable for high leakage current. Use of original
Danfoss installation box or installation kit 175N2207 is recommended.
3.3.7 Caution
PE connection
The metal pin in the corner(s) of the electronic part
and the bronze spring in the corner(s) of the installa-
tion box are essential for the
protective earth
connec-
tion. Make sure they are not loosened, removed, or
violated in any way.
NB!
Do not plug/unplug the electronic part with mains volt-
age switched on.
VLT
®
Decentral FCD 300 Design Guide
3 Installation
MG.90.S1.02 - VLT
®
is a registered Danfoss trademark
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