In Hevacomp Connect where it checks the energy let through calculation I am trying to work out how I2t (current squared multiplied by time) is calculated. On the Results tab for each circuit you can view the value of I (current) and the time duration of the fault. I was expecting that these values would equate to the Energy (I2t) result shown on the same page.
For a particular circuit I get the following results: Short circuit current is 5166amps, fault duration of 0.018secs and disconnection time of 0.003secs. Energy (I2t) is shown as 29,096.I've checked the help file page which concurrs with my expectations which are as the regulations lay out the calculation, but this doesn't explain why Energy (I2t) result isn't current squared multiplied by time as per the other results shown on that page for that circuit.. Any explanation of how the software performs this calculation would be appreciated.
Hi Derek - Can I check what device you are using on this circuit? That will have a baring on what you are seeing.regards,
Duncan Brown
Hi. The protective device is an Eaton Memshield 3 range EMCH type C 63 amp.Thanks
Hi Derek - there are 3 potential ways that i2t is considered:If the device is Energy Limiting then there is figure in the device data file that is considered (A BS88, for example)If there is i2t curve for the device, the figure will be taken from there.
If none of the above then the i2t is calculated from results data.In this case, there is an i2t curve for the device, so the figure is derived from there, as you can see where I have highlighted in blue:
Regards,
Answer Verified By: Duncan Brown
That answers my question nicely - thank you.
Glad to have helped, Derek. I thought this information may prove useful for other users, so I have generated a Wiki article which should make it easier for other users to search for.