Device
Select the type of protective device to be used
- Unknown
- HRC Breaker
- B Curve Breaker
- C Curve Breaker
- D Curve Breaker
- Adjustable Breaker
- Custom Breaker
Rating
Enter the nominal rating of the selected protective device.
Overload
Short Circuit
The fields under this heading are for the purpose of cable sizing only. PowerPac will check to see whether the cable withstand the fault.
Fault Clearing Time
This is the time taken to clear an upstream fault at the point of connection for the cable being calculated. Fault clearing time is measured in seconds.
Trip Multiplier
Enter the multiplier or current rating required to cause the selected protective device to function in the specified fault clearing time. The multiplier and fault clearing time can both be obtained from a time current curve for the device being used. These curves can be obtained from the device manufacturer
Let Through Energy
The let through energy is calculated from the fault clearing time and the trip multiplier above. If the trip multiplier or current is not specified, the prospective short circuit current at the start of the cable run is used with the specified time to calculate a value for the let through energy.
NOTE: Not entering this data may result in cables larger than required. If this is the case, entering these values from a time current curve for the selected device will lower that required cable size as the protective device should trip before the prospective short circuit current is reached
Earth Fault
These fields are for the purpose of calculating and checking Earth Fault Loop Impedance
Earth Fault Trip Time
Select the desired trip time in case of an earth fault.
Instant Trip Multiplier
This is the multiplier or current that will trigger the protective device in the selected earth fault trip time. If a Type B, C or D curve breaker is selected then the trip multiplier will default to 4, 7.5 and 12.5
respectively. For fuses, the fusing current is obtained from AS2005.21.2
RCD / Earth Leakage Protection
Select this option if this circuit is directly protected by an RCD or Earth Leakage Protection device. If selected then earth fault loop impedance is not taken into consideration for tripping of the protective device. If not selected then earth fault loop is calculated for the tripping of the protective device
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