Fuses - Danfoss VLT AutomationDrive FC 300 Design Manual

FC 300 Design Guide
If it is necessary to break the shield to install a motor isolator or motor contactor, the shield
must be continued at the lowest possible HF impedance.
Cable length and cross-section
The adjustable frequency drive has been tested with a given length of cable and a given cross-section
of that cable. If the cross-section is increased, the cable capacitance - and thus the leakage current
- increases, and 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 must be removed and sealed by
neutral acid-free grease before the conductor is connected.
Furthermore, the terminal screw must be retightened after two days due to the softness of the aluminum. It
is crucial to keep the connection a gas-tight joint, otherwise the aluminum surface will oxidize again.

Fuses

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Branch circuit protection:
In order to protect the installation against electrical and fire hazard, all branch circuits
in an installation, switch gear, machines etc., must be short circuit- and overcurrent-
protected according to the national/international regulations.
Short circuit protection:
The adjustable frequency drive must be protected against 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 adjustable frequency drive provides
full short circuit protection in case of a short circuit on the motor output.
Overcurrent protection:
Provide overload protection to avoid fire hazard due to overheating of the cables in the installation.
The adjustable frequency drive is equipped with an internal overcurrent protection that can be used
for upstream 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 out according to national regulations.
To comply with UL/cUL approvals, use pre-fuses according to the following tables.
200-240 V
FC 30X Bussmann
Type RK1
K2-K75 KTN-R10
1K1-2K2 KTN-R20
3K0-3K7 KTN-R30
How to Install
Bussmann Bussmann
Type J Type T
JKS-10 JJN-10
JKS-20 JJN-20
JKS-30 JJN-30
MG.33.B3.22 - VLT is a registered Danfoss trademark
SIBA Littel fuse
Type RK1 Type RK1
5017906-010 KLN-R10
5017906-020 KLN-R20
5012406-032 KLN-R30
Ferraz- Ferraz-
Shawmut Shawmut
Type CC Type RK1
ATM-R10 A2K-10R
ATM-R20 A2K-20R
ATM-R30 A2K-30R
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