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PV cylindrical fuse system, 3NW7 0..-4, 3NW6 0..-4

PV fuse system NH, 3NH7 3..-4, 3NE1 3..-4D

Special requirements are placed on fuses for application in photovoltaic systems. These fuses have a high DC rated voltage and a disconnect characteristic specially designed to protect PV modules and their connecting cables (the newly defined operational class gPV). It is also crucial that the PV fuses do not age in spite of strongly alternating load currents, in order to ensure high plant availability throughout the service life of the PV system. The fuses must also be able to withstand even high temperature fluctuations without damage. These requirements were only incorporated into an international standard in recent years and have now been published as IEC 60269-6. All Siemens photovoltaic fuse systems comply with this new standard. Furthermore, they also already comply with the recently agreed corrections to the characteristic curves, which will be incorporated in the next standard update.

The IEC cylindrical fuses used as phase fuses also correspond to the characteristic curves specified in the UL standard UL 2579. The non-fusing current Inf and fusing current If test currents are crucial to the course of the characteristic curves.




Current IEC standard

1.13 x In

1.45 x In

UL standard

1.0 x In

1.35 x In

Future IEC standard

1.05 x In

1.35 x In

Siemens fuses

1.13 x In

1.35 x In

These test currents of gPV phase fuses to 32 A apply for a conventional test duration of one hour; at Inf, the fuse must not shut down within an hour, at If, it must shut down within an hour

The PV cylindrical fuses of size 10 mm x 38 mm offer an especially space-saving solution for the protection of the strings.

The fuse holders of size 10 x 38 mm can be supplied in single-pole and two-pole versions with and without signal detectors. In the case of devices with signal detector, a small electronic device with LED is located behind an inspection window in the plug-in module. If the inserted fuse link is tripped, this is indicated by the LED flashing. The devices have a sliding catch that enables removal of individual devices from the assembly. The infeed can be from the top or the bottom. As the cylindrical fuse holders are fitted with the same anti-slip terminals at the top and the bottom, the devices can also be bus-mounted at the top or the bottom.

The PV fuses in LV HRC design are usually used as cumulative fuses upstream of the inverter. In addition, they can also be used for protecting groups (PV subarrays). For the PV cumulative fuses of size 1, the standard LV HRC fuse bases are available. For PV cumulative fuses of size 1L, 1XL, 2L, 2XL and 3L, we have developed a special 3NH7...-4 fuse base with a swiveling mechanism that combines maximum touch protection with maximum user-friendliness. This makes it possible to change fuses safely and without the need for any tools, such as a fuse handle This provides safe and fast access even in an emergency.

Our cylindrical fuse holders and fuse bases with swiveling mechanism comply with the IEC 60269-2 standard and are considered fuse disconnectors as defined in the IEC 60947 switchgear and controlgear standard. Under no circumstances are they suitable for switching loads.

To ensure that fuses are correctly selected and dimensioned, the specific operating conditions and the photovoltaic module data must be taken into account when calculating voltage and current ratings.


  • Protection of the module and the module connection leads in the event of reverse currents
  • Safe disconnection in case of fault currents reduces the risk of fire due to DC electric arcs
  • Safe isolation when the fuse holder / fuse base is open