Application Note – Hi-Tech 1 (CLF)
1
Current peak Fuse Melting Current interruption Application Note Why Use Current-Limiting Fuses? Written by Dan Gardner, PE To minimize the risk of eventful/catastrophic failure of distribution equipment by limiting the energy and the peak current let through during a fault. Expulsion fuses and breakers do not limit the energy let-through and sometimes take many loops or even cycles to interrupt. They also do not limit the peak current seen during a fault. Current-limiting fuses drastically reduce the energy let through during a fault and limit the peak current, making it much less likely for equipment to fail eventfully. Example: With an available fault current of only 2,000A, the first loop of I 2 t let-through during a fault can be as much as 140,000A 2 sec for an X/R or 10. By comparison, a 12K EXT or a 35A OS current-limiting fuse limits the I 2 t let-through during the fault to only 10,000A 2 sec for any fault up to 50,000A . To interrupt high fault currents (up to 50,000A rms symmetrical) and to remove faulted equipment in areas where the available fault current level exceeds the interrupting capability of other protective devices. To improve system safety. In addition to reducing the likelihood of an eventful failure of a piece of equipment, current-limiting fuses also address concerns for potential fire safety hazards or safety issues associated with populated areas where expulsion gases are not acceptable. The noiseless operation of a current-limiting fuse also alleviates concerns for the loud noise (“bang”) during fuse operation. To improve power quality by supporting the system voltage and reducing the “blink” time during faults. To improve coordination with source side devices (coordination up to 50kA). Application Note – Hi-Tech 1 Page 1 of 1 March 2007 Expulsion Fuse Operation Current-limiting Fuse Operation Prospective Fault Current Fuse Current Current interruption Fuse Melting Current peak
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Current Limiting Fuse
Transcript of Application Note – Hi-Tech 1 (CLF)
Current peak
Fuse Melting
Current interruption
Application NoteWhy Use Current-Limiting Fuses?Written by Dan Gardner, PE
To minimize the risk of eventful/catastrophic failure of distribution equipment by limiting the energy and the peak current let through during a fault. Expulsion fuses and breakers do not limit the energy let-through and sometimes take many loops or even cycles to interrupt. They also do not limit the peak current seen during a fault. Current-limiting fuses drastically reduce the energy let through during a fault and limit the peak current, making it much less likely for equipment to fail eventfully.
Example: With an available fault current of only 2,000A, the first loop of I2t let-through during a fault can be as much as 140,000A2sec for an X/R or 10. By comparison, a 12K EXT or a 35A OS current-limiting fuse limits the I2t let-through during the fault to only10,000A2sec for any fault up to 50,000A.
To interrupt high fault currents (up to 50,000A rms symmetrical) and to remove faulted equipment in areas where the available fault current level exceeds the interrupting capability of other protective devices.
To improve system safety. In addition to reducing the likelihood of an eventful failure of a piece of equipment, current-limiting fuses also address concerns for potential fire safety hazards or safety issues associated with populated areas where expulsion gases are not acceptable. The noiseless operation of a current-limiting fuse also alleviates concerns for the loud noise (“bang”) during fuse operation.
To improve power quality by supporting the system voltage and reducing the “blink” time during faults.
To improve coordination with source side devices (coordination up to 50kA).
Application Note – Hi-Tech 1 Page 1 of 1March 2007
Expulsion Fuse Operation Current-limiting Fuse Operation
Prospective Fault Current
Fuse Current
Current interruption
Fuse Melting Current peak
