issue:
the customer wants to know what is the TFL and what is its function and how it works. Also he wants to know the time-current curves of the TFL (XF type fuses).

Environment:
Ringmaster characteristics

Resolution:
TFL (Time Fuse Link) is used in Ringmaster as one of the options for phase overcurrent and earth fault inverse time protection. This option is suitable for transformer protection up to 1600 kVA.

Theory of operation:
The current transformer feeds a trip coil that is normally shunted by a time fuse link.In the event of a fault the fuse ruptures, diverting all the fault current through the trip coil, tripping the breaker. A residually connected trip coil provides instantaneous earth fault protection.



Attached is the Time-Current Characteristics for TFL (XF fuses) used.
Below is the link for the Ringmaster catalog
https://www.se.com/ww/en/product-range/968-ringmaster/#documents

Thank you
BR

Released for: Schneider Electric Nigeria