4.16 kV Motor and Transformer Fuse Rating

[mazen]

Dear Sir;

1. How do you size the 5 kV Fuse for a motor load,i.e.
the "R" rated Fuse?.

[sig][/sig]

 

[jbartos]

Suggestion:
Contact "R" rated fuse manufacturer and give the manufacturer motor load nameplate data. This would probably be the most accurate protection of your motor load. You are welcome to provide more information about the motor load, e.g. motor nameplate data, and the R fuse manufacturer. [sig][/sig]

 

[jhalm]

Some old information I have notes that NEMA SG.2-46-10 (not sure if standard is current but explanation would still applicable) states that the fuse will melt in a range of 15 to 35 seconds at a current value equal to 100 * "R" number of the fuse. As such, you need to get the proper curve data (curves) from a manufacturer to verify what is suitable for your application to adequately protect motor when compared to damage curves for motor.