Fuses And Circuit Breakers; Fuses; D-Frame Short Circuit Current Rating (Sccr); Recommendations - Danfoss VLT AutomationDrive FC 300 Design Manual

Electrical Installation

7.2 Fuses and Circuit Breakers

7.2.1 Fuses

It is recommended to use fuses and/or circuit breakers on
the supply side as protection in case of a component
breakdown inside the frequency converter.
NOTICE
This is mandatory to ensure compliance with
IEC 60364 for CE or NEC 2009 for UL.
WARNING
Personnel and property must be protected against the
consequence of internal component breakdown in the
frequency converter.
Branch Circuit Protection
In order to protect the installation against electrical and
fire hazard, all branch circuits in an installation, such as
those found in switch gear and machines, must be
protected against short-circuit and over-current according
to national/international regulations.
NOTICE
These recommendations do not cover
branch circuit protection for UL.
Short-Circuit Protection
Danfoss recommends using the fuses/circuit breakers
mentioned in 7.2.4 Power/Semiconductor Fuse Size to
protect service personnel and property in case of
component break-down in the frequency converter.
7.2.2 D-frame Short Circuit Current Rating
(SCCR)
If the frequency converter is not supplied with a mains
disconnect, contactor, or circuit breaker, the Short Circuit
Current Rating (SCCR) of the frequency converters is
100,000 A at all voltages (380–690 V).
If the frequency converter is supplied with a mains
disconnect, the SCCR of the frequency converter is 100,000
amps at all voltages (380–690 V).
If the frequency converter is supplied with a circuit
breaker, the SCCR depends on the voltage. See Table 7.27.
415 V 480 V
D6h frame 120,000 A 100,000 A
D8h frame 100,000 A 100,000 A
Table 7.27 Frequency Converter Supplied with a Circuit Breaker
®
VLT AutomationDrive FC 300 Design Guide 90-1200 kW
If the frequency converter is supplied with a contactor-only
option and is externally fused according to Table 7.28, the
SCCR of the frequency converter is as follows:
D6h frame
D8h frame (not
including the
N250T5)
D8h frame
(N250T5 only)
Table 7.28 Frequency Converter Supplied with a Contactor
1) With a Bussmann type LPJ-SP or Gould Shawmut type AJT fuse.
450 A max fuse size for D6h and 900 A max fuse size for D8h.
2)
Must use Class J or L branch fuses for UL approval. 450 A max fuse
size for D6h and 600 A max fuse size for D8h.

7.2.3 Recommendations

In case of malfunction, failure to follow these recommen-
dations may result in personnel risk and damage to the
frequency converter and other equipment.
Danfoss recommends the fuses from the following tables.
Selecting the proper fuses and circuit breakers minimises
damage due to an over-current condition within the
frequency converter. If fuses/circuit breakers are chosen
according to recommendations, possible damages are
limited mainly to inside the unit.
For further information, see Application Note for FC 100, FC
200 and FC 300 Fuses and Circuit Breakers.
600 V 690 V
65,000 A 70,000 A
42,000 A 30,000 A
MG34S202 - Rev. 2013-08-19
415 V 480 V
IEC 1) UL 2)
100,000 A 100,000 A
100,000 A 100,000 A
100,000 A Consult
factory
WARNING
600 V 690 V
UL 2) IEC 1)
100,000 A 100,000 A
100,000 A 100,000 A
Not applicable
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