how do you size a cartridge fuse to fit a particular disconnect? in the switchgear i need fuses it says only "type j" but i'm not sure how to order them so they fit right.

if your disco states type j, then you only need spec voltage & amperage...

a listed disconnect will indicate the size, type ocpd required.

An example is http://www.bussmann.com/library/docs/LowPeakCat.pdf

Their Class-J versions [LPJ-series] up to 600A @ 600V and 300,000AIC.




[This message has been edited by Bjarney (edited 11-16-2002).]

Just make sure you follow what the blue print says. You might fail a final inspection if the print calls for a type "J" fuse and you have a type "R" fuse instead.

Mike,
What is a j-type fuse?.
We work on the following type fuses,(HRC)
to IEC Requirements:
P1: Semi-conductor Devices Protection- 1.0-
1.1 protection.
Q1: General protection, lighting power.
Q2: General protection Sub-Mains, other Equipment.
R: Motor rated links for 3 Phase or other motors upon start-up.

Trumpy—in general, 600V Class-J fuses are available in "semi-fast" [non-motor]and "slow" time-current curves [motor]. About 10 years ago the interrupting rating of 300KA became available in the US. At that time the justification was that there were a ±dozen US cities with "downtown" electric networks that were so stiff that 200kA interrupting was underrated.