time limit fuses
time limit fuses
(OP)
this is a homework question but as I've found no info on the net I hoping some people familiar with this older technology can help out.
In what application, or when were, time limit fuses preferred over other solutions for protection. Very little on the net in discussing application of this legacy technology which may still be in place in some installations.
Any help appreciated even if a link to further reading material.
thanks
In what application, or when were, time limit fuses preferred over other solutions for protection. Very little on the net in discussing application of this legacy technology which may still be in place in some installations.
Any help appreciated even if a link to further reading material.
thanks






RE: time limit fuses
RE: time limit fuses
RE: time limit fuses
RE: time limit fuses
There is a schematic diagram in the Schneider document showing the principle of operation. It is about as simple as it gets.
Some DNO's install a TLF in the earth fault element, which you may question the need for, when you are protecting a delta winding, but it does give positive evidence of a fault. If a TLF blows it is useful to break it open to see if the element has melted to rule out another mode of failure/cause of tripping.
The TLF is usually graded with low voltage fuses, which may be 400-600A. If the substation feeds a customer with their own HV network, or their own transformer, then the protection would be via self powered relays rather than TLF's.
Regards
Marmite
RE: time limit fuses
This gave better and cheaper protection than changing out the disconnect switch for a higher rated switch. In some instances changing to a higher rated switch may require the conductor and conduit sizes to be increased.
In initial installations a smaller disconnect switch was often adequate.
In the event that a motor was to be replaced with a larger motor, the use of dual element fuses would often avoid the need to change out the disconnect switch to a larger size.
Bill
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"Why not the best?"
Jimmy Carter
RE: time limit fuses