FC 300 Design Guide
How to Install
If it is necessary to bre ak the shield to install a mo tor isol ator or motor contactor, the shield
must be continued at the lowest possible HF impedance.
Cable length and cross-sectio n
The adjustable frequency drive has been tested with a given lengt h of cable and a given cross-section
of that cable. If the cross-sec tion is increased, the cable capacitance - and thus the leaka ge current
- increases, a nd the cable length must be reduced correspondingly.
Switching frequency
When adjustable frequency drives are used together with LC filters to reduce the acoustic noise from a
motor, the switching frequency must be set according to the LC filter instruction in Par. 14-01.
Aluminum conductors
Aluminum conductors are not recommended. Terminals can accept aluminum conductors
but the conductor surface must be clean and the oxidation m ust be removed and sealed b y
neutral acid-free grease before the conductor is connected.
Furthermore, the terminal screw must be retigh tene d after two days due to the softness of the a luminum. It
is crucial to keep the connection a gas-tight joint, otherwise the aluminum surface will oxi dize again.
" Fuses
Branch circuit protection:
In order to protect the installation against electrical and fire hazard, all b ranch circuits
in an installation, switch gear, machines etc., must be short circuit- and overcurrent-
protected according to the national/international r
egulations.
Short circuit protection:
Theadjustablefrequencydrivemustbeprotectedagainst short circuit to avoid electrical or fire
hazard. Danfoss recommends using the fuses mentioned below to protect service personnel and
other equipment in case of an internal failure in the
drive. The ad justa ble frequency drive p rovides
full short circuit protection in case of a short circuit on the motor output.
Overcurrent protection:
Provide overload protection to avoid fir e hazard due to overheating of the cables in the installation.
The adjustable frequency d rive is equipped w
ith an internal overcurrent protection that can be used
for upstre am overload protection (UL-applications excluded ). See par. 4 -18 . Moreover, fuses or
circuit breakers can be used to provide the overcurrent protection in the installation. Overcurrent
protection must always be carried ou
t according to national regulations.
To comply with UL/cUL approvals, use
pre-fuses according to the following tables.
200-240 V
FC 30X Bussmann Bus smann Bussmann S IBA Littel fuse
Ferraz-
Shawmut
Ferraz-
Shawmut
Type RK1 Type J Type T Type RK1 Type RK1 Type CC Type RK1
K2-K75 KTN-R10 JKS-10 JJN-10 5017906-010 KLN-R10 ATM-R10 A 2K-10R
1K1-2K2 KTN-R20 JKS-20 JJN-20 5017906-020 KLN-R20 AT M-R20 A2K-20R
3K0-3K7 KTN-R30 JKS-30 JJN-30 5012406-032 KLN-R30 AT M-R30 A2K-30R
91
MG.33.B3.22 - VLT is a registered Danfoss trademark
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