LV HRC Fuse Time Current Curve Calculator Guide
What is it?
The time current tool provides generic clearance curves for the DIN NH and BS88 industrial fuses that are manufactured to the standard IEC 60269. The calculator produces a time current curve characteristic plot for up to two curves and provides a clearance time against the entry of a specific current. It will also provide a current against the entry of a specific time.
Why would you use it?
By using the calculator, the entry of a specific arcing current figure will return a clearance or disconnection time. The curves take into account the total clearance times and are not just the pre-arcing time.
Where would you use it?
The calculator is based upon DIN NH and BS88 industrial fuses that are manufactured to the standard IEC 60269. The limitations are:
- Three-phase short circuits up to a maximum secondary voltage of 600 volts.
- Clearance times between 0.05 and 10 seconds.
- Industrial fuses only, motor fuses not included.
- Current ratings between 32 and 1250 amperes.
How do you use it?
A screen shot of the calculator is shown in Figure 14.29.
Figure 14.29 LV HRC TCC (Time Current Curve) Calculator
TCC 1 Amp Rating (NH DIN Fuse)
A dropdown list menu gives a range of choices between 32 amperes and 1250 amperes for NH DIN Fuses.
TCC 2 Amp Rating (BS88 fuse)
A dropdown list menu gives a range of choices between 32 amperes and 1250 amperes for BS88 Fuses.
TCC Chart
This will display both TCC 1 (NH DIN Fuse) and TCC 2 (BS88 Fuse) fuse time current curves. Either one can be deselected by clicking on the associated colour block at the top of the graph.
Enter Specific Input Time
By entering a specific input time ranging from 0.01 to 10 seconds), a corresponding clearance current for the associated fuse will be given. (This value will be displayed in amperes)
Enter Specific Input Current
By entering a specific input current in amperes (guidance ranges will be displayed depending on the selected fuse amps), a corresponding clearance time for the associated fuse will be given. (This value will be displayed in seconds)