Contents
What is the time current curve for a fuse?
curves. The fuse specification typically will include a life requirement at 100% of rating and maximum opening times at overload points (usually 135% and 200% of rating depending on fuse standard characteristics). A time-current curve represents average data for the design; how ever, there may be some differences in the values for any one
Which is the No operate region on a fuse?
The area to the right and above the device time-current curve is the ‘operate’ region while the area to the left and below the device time-current curve is the ‘no operate’ region. In figure 1, the area to the left and below the fuse time-current curve is its ‘no operate’ region.
What does the interrupting rating on a fuse mean?
INTERRUPTING RATING: Also known as breaking capacity or short circuit rating, the interrupting rating is the maximum approved current which the fuse can safely interrupt at rated voltage. During a fault or short circuit condition, a fuse may receive an instantaneous overload current many times greater than its normal operating current.
What do you need to know about time current curves?
1 Time Current Curves. A Time Current Curve (TCC) is a graphical representation of the operating characteristics of overcurrent protection devices at different magnitudes of fault currents. 2 Coordination Time Interval. So when can we say that overcurrent protection devices are effectively coordinated? 3 Conclusion. 4 References.
What does the current rating on a fuse mean?
CURRENT RATING:The nominal amperage value of the fuse. It is established by the manufacturer as a value of current which the fuse can carry, based on a controlled set of test conditions (See RERATING). Catalog Fuse part numbers include series identification and amperage ratings.
What is the resistance of a fractional amperage fuse?
RESISTANCE:The resistance of a fuse is usually an insignificant part of the total circuit resistance. Since the resistance of fractional amperage fuses can be several ohms, this fact should be considered when using them in low-voltage circuits. Actual values can be obtained by contacting Littelfuse.
How long does it take for a fuse to open?
The fuse must carry 100% of its ampere rating and must stabilize at a temperature that does not exceed a 75ºC rise. The fuse must open at 135% of rated current within one hour. It also must open at 200% of rated current within 2 minutes for 0-30 ampere ratings and 4 minutes for 35-60 ampere ratings.