Danfoss FC 100, FC 200, FC 300 Application guide
Fuses and Circuit Breakers Application Note for FC 100, FC 200 and FC 300 Fuses and Circuit Breakers
1 Fuses and Circuit Breakers |
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1.1.1 Fuses
A frequency converter that works correctly limits the current it can draw from the supply. Still, it is recommended to use fuses and/ or Circuit Breakers on the supply side as protection in case of component break-down inside the frequency converter (first fault).
NOTE
This is mandatory in order to ensure compliance with IEC 60364 for CE or NEC 2009 for UL.
1.1.2 Energy Required to Clearing the Circuit
It is important to choose a fuse/Circuit Breaker with a low I2t [A2s]. This parameter is the energy required to clearing and is a measure of the damaging effect on the frequency converter.
Fuses offer better protection of the frequency converter than Circuit Breakers as I2t is smaller for fuses.
I2taR fuse << I2tgG fuse << I2tcircuit breaker for the same nominal
value
WARNING
Personnel and property must be protected against the consequence of component break-down internally in the frequency converter.
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 protected against short-circuit and over-current according to national/international regulations.
NOTE
The recommendations given do not cover Branch circuit protection for UL!
Short-circuit protection:
Danfoss recommends using the fuses/Circuit Breakers listed in 1.1.6 CE Compliance and 1.1.7 UL Compliance to protect service personnel and property in case of component breakdown in the frequency converter.
Over current protection:
The frequency converter provides overload protection to limit threats to human life, property damage and to avoid fire hazard due to overheating of the cables in the installation. The frequency converter is equipped with an internal over current protection (4-18 Current Limit) that can be used for upstream overload protection (UL-applications excluded). Moreover, fuses or Circuit Breakers can be used to provide the over current protection in the installation. Over current protection must always be carried out according to national regulations.
The fastest clearing is done with an aR fuse (partial range accompanied protection for semiconductors) that is faster than a gG fuse (wide-range general-purpose protection for cables, conductors and wires). Circuit Breakers are slower.
1.1.3 Safely Breaking the Current
Fuses and Circuit Breakers must be capable of safely breaking the current in the event of a short circuit. When a large electric current is interrupted an arc may form and if the breaking capacity of a fuse or circuit breaker is exceeded then it may not be able to extinguish this arc and the current will continue, which might have severe consequences.
This breaking capacity is known as the Short Circuit Current Rating (SCCR).
The prospective short circuit current (PSCC) is the highest electric current which can exist in a particular electrical system under short circuitand ground fault conditions and is determined by the voltage and impedance of the supply system.
With gG fuses, the SCCR is 100 kA rms (symmetrical) which means that it will be possible to disconnect a PSCC of up to 100 kA rms (symmetrical). The recommended aR fuses and Circuit Breakers have a lower SCCR which means that they will not be able to disconnect a PSCC of that magnitude. The data sheets must be consulted for details.
NOTE
In general, be aware that your fuse/Circuit Breaker must be capable of handling the PSCC.
MN.90.T1.02 - VLT®is a protected Danfoss trademark |
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Fuses and Circuit Breakers |
Application Note for FC 100, FC 200 and FC 300 Fuses and Circuit Breakers |
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1 1 1.1.4 Fuses and Circuit Breakers
The selection of fuse and/or Circuit Breaker will depend on preferences and on the installation in question. Sometimes it is necessary to combine the two.
Fuses
A nonrenewable fuse interrupts excessive current by clearing. Fuses are selected to allow passage of normal current and of excessive current only for short periods. After clearing, the fuse must be replaced.
gG-fuses offer full protection and can be used alone or as electrical branch-fuse.
NOTE
aR semi-conductor fuses must never be used as the only protection. Always combine with gG fuses or a Circuit Breaker depending on the prospective current. Alternatively, gRL fuses can be used alone.
Circuit Breakers
A Circuit Breaker is an automatically-operated electrical switch that is designed for overload protection. It can be used to interrupt excessive current by disconnecting but it is slower than a nonrenewable fuse. Unlike a fuse, which operates once and then has to be replaced, a circuit breaker can be reset (either manually or automatically) to resume normal operation. When a current is interrupted, an arc is generated. Different techniques are used to extinguish the arc.
NOTE
Circuit Breakers should generally not be used as the only protection. There are some Circuit Breakers now, however, that can do the job. Generally, combine with a gG fuse or a bigger Circuit Breaker branch-fuse for the desired protection depending on the prospective current.
Illustration 1.2 Circuit Breakers should Generally not be used as the
Only Protection
Illustration 1.1 gG Fuses offer Full Protection and can be Used
Alone or as Electrical Branch-fuse
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MN.90.T1.02 - VLT®is a protected Danfoss trademark |
Fuses and Circuit Breakers |
Application Note for FC 100, FC 200 and FC 300 Fuses and Circuit Breakers |
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1.1.5 Recommendations |
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WARNING
In case of malfunction, not following the recommendation may result in personnel risk and damage to the frequency converter and other equipment.
The following tables list the recommended rated current. Recommended fuses are of the type gG for small to medium power sizes. For larger powers, aR fuses are recommended. For Circuit Breakers, Moeller types have been tested to have a recommendation. Other types of circuit breakers may be used provided they limit the energy into the drive to a level equal to or lower than the Moeller types.
If fuses/Circuit Breakers according to recommendations are chosen, possible damages on the frequency converter will mainly be limited to damages inside the unit.
NOTE
Following the recommendations puts the direct fuses/Circuit Breaker in place (a, b, c... in figure below). It does NOT make up for considering combined protection or branch circuit protection (see x in illustration below).
NOTE
The dimensions in Table 1.2 are for an ambient temperature at 20C. At an ambient temperature at 40C, use Recommended Max. fuse for gR/aR.
MN.90.T1.02 - VLT®is a protected Danfoss trademark |
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Fuses and Circuit Breakers Application Note for FC 100, FC 200 and FC 300 Fuses and Circuit Breakers
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1.1.6 CE Compliance |
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Fuses or Circuit Breakers are mandatory to comply with IEC 60364. Danfoss recommend using a selection of the following. |
The fuses below are suitable for use on a circuit capable of delivering 100,000 Arms (symmetrical), 240V, or 480V, or 500V, or 600V depending on the drive voltage rating. With the proper fusing the drive short circuit current rating (SCCR) is 100,000 Arms.
Enclosure |
FC 300 Power |
FC 100/200 |
Recommended |
Recommended |
Recommended |
Max trip level |
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Power |
fuse size |
Max. fuse |
circuit breaker |
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Size |
[kW] |
[kW] |
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Moeller |
[A] |
A1 |
0.25-1.5 |
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gG-10 |
gG-25 |
PKZM0-16 |
16 |
A2 |
0.25-2.2 |
0.25-2.2 |
gG-10 (0.25-1.5) |
gG-25 |
PKZM0-25 |
25 |
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gG-16 (2.2) |
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A3 |
3.0-3.7 |
3.0-3.7 |
gG-16 (3) |
gG-32 |
PKZM0-25 |
25 |
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gG-20 (3.7) |
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B3 |
5.5 |
5.5-11 |
gG-25 |
gG-63 |
PKZM4-50 |
50 |
B4 |
7.5-15 |
15-18 |
gG-32 (7.5) |
gG-125 |
NZMB1-A100 |
100 |
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gG-50 (11) |
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gG-63 (15) |
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C3 |
18.5-22 |
22-30 |
gG-80 (18.5) |
gG-150 (18.5) |
NZMB2-A200 |
150 |
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aR-125 (22) |
aR-160 (22) |
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C4 |
30-37 |
37-45 |
aR-160 (30) |
aR-200 (30) |
NZMB2-A250 |
250 |
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aR-200 (37) |
aR-250 (37) |
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A4 |
0.25-2.2 |
0.25-2.2 |
gG-10 (0.25-1.5) |
gG-32 |
PKZM0-25 |
25 |
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gG-16 (2.2) |
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A5 |
0.25-3.7 |
0.25-3.7 |
gG-10 (0.25-1.5) |
gG-32 |
PKZM0-25 |
25 |
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gG-16 (2.2-3) |
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gG-20 (3.7) |
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B1 |
5.5-7.5 |
5.5-11 |
gG-25 (5.5) |
gG-80 |
PKZM4-63 |
63 |
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gG-32 (7.5) |
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B2 |
11 |
15 |
gG-50 |
gG-100 |
NZMB1-A100 |
100 |
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C1 |
15-22 |
18.5-30 |
gG-63 (15) |
gG-160 (15-18.5) |
NZMB2-A200 |
160 |
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gG-80 (18.5) |
aR-160 (22) |
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gG-100 (22) |
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C2 |
30-37 |
37-45 |
aR-160 (30) |
aR-200 (30) |
NZMB2-A250 |
250 |
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aR-200 (37) |
aR-250 (37) |
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Table 1.1 200-240V, Frame Sizes A, B, and C
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MN.90.T1.02 - VLT®is a protected Danfoss trademark |
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