S&C has announced an enhancement to the SM-20, SML-20, and SME-20 Power Fuses: a wear indicator feature for S&C’s Power Fuse Silencer.
The red metal indicator, located inside the Silencer, erodes with each fuse operation and is designed to be completely worn away after three full-fault operations, denoting that the Silencer has no remaining life and should be replaced. Upon interruption of lower-level faults, the indicator will show that the Silencer can be reused. Operating personnel are thus assured that, upon re-fusing with a new SMU-20 Fuse Unit, there’s useful life remaining in the associated Silencer. Replacement of the Silencer is dependent on the cumulative fault current interrupted, not a fixed number of operations.
Bear in mind that even if the Silencer is used beyond three full-fault operations, S&C’s Silencer is still capable of additional full-fault interruptions. So the Silencer provides a margin for error even if it is not replaced when so indicated.
Look for the new wear indicator feature starting in mid 2007.