CHAPTER 3 - INSTALLATION AND CONNECTION
51
Ultra-fast fuses (aR), with l²t smaller than or equal to 75 % of the value
of the SCR indicated (A²s) in table 3.10 and table 3.11.
NOTE!
The maximum I²t of the fuse of the SSWs varies according to the design
of the SCR used; therefore, higher rated currents may present lower I²t.
The fuse rated current should preferably be equal to or higher than the
motor starting current in order to prevent cyclic overloads and the tripping
of the fuse in the prohibited area of the Time x Current curve.
The proper sizing of the fuse should take into account: the local standards
for electrical installations, the starting cycle, number of starts per hour,
starting current and starting time, ambient temperature and altitude.
For the correct sizing of the fuses, see WEG Fuse Catalog:
www.weg.net
Automation-FusesaRandgL/gG-TypeNHBladeContact,NHFlush
End and Diametral.
Annex 1: Sizing Criteria for Ultra-Fast Fuses aR Blade Contact and Flush
End.
Annex 2: Table for aR Fuse Sizing to Protect SSW Soft-Starters and
CFW Inverters.
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