PFC fuses
PFC fuses
(OP)
Hi, I am hesitating in this issue (POWER FACTOR CONNECTİON CAPACİTORS' LİNE PROTECTİVE FUSE RATİNG )since I am not sure to which criteria we must select the fuses. I mean must we use a motor fuse since the in rush current makes necessary that a delaying type fuse is used. If this is so for sure (I am asking you of this) so what ratio must be between capacitor rated current and fuse rated current? I am confused since there are some sources which says at least 1,5 -1,6 ratio must be between them. Thanks a lot.






RE: PFC fuses
RE: PFC fuses
What is the voltage? Are these independent caps or connected to a motor? If motor O/L and OCPD is protecting the caps, you may not need individual cap protection. Whether or not they have series reactors to limit inrush makes a difference too.
You can check codes applicable to your project, I can only provide NEC reference (Article 460) which only states that for LV PFCC the OCPD (over current protective device) rating shall be as low as practicable (but still able to withstand capacitor inrush currents). Dual element fuse helps in this regard. For medium and high voltage only short circuit protection is required.
Rafiq Bulsara
http://www.srengineersct.com
RE: PFC fuses
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RE: PFC fuses
One thing to keep in mind is that the fuse should protect against the capacitor case rupturing. You might be able to get a capacitor case rupturing curve from the capacitor manufacturer and then plot the fuse curve over top to ensure the fuse protects the capacitor.
RE: PFC fuses