2. MZ.23132: ETAP Arc Flash Study

My first project…

My first project was to update the ETAP model and perform an arc flash evaluation of circuit A4 in

substation 7.

In accordance with…

According to RSP-1163 and SP-60-05, our ETAP model must be maintained accurately to reflect the power distribution system as well as use ETAP to calculate arc flash levels and limit the

incident energy or IE to comply with NFPA and IEEE standards.

To complete this task…

To complete this task, I analyzed and field verified the single line drawings of SWRK 330A and B

on 7A4 and updated the ETAP circuit of 7-A4 to address any discrepancies between the single line and

ETAP model.

Then, I used…

Then, I used ETAP to conduct an arc flash study of the switchracks and examined IE calculations to determine and ensure electrical safety during breaker operation.

We found that…

We found that the incident energies for switchracks 330A and B were deemed safe enough for a qualified person to operate the disconnect devices.

However, when evaluating…

However, when evaluating the main 7-A4 bus, the IE was roughly 45 calories per square centimeter. To reduce this to a safer level, we needed to enable maintenance mode on its protective relay device, which allows personnel to safely disconnect when needed.

After completing the…

After completing the study and updates, I created an ETAP template with the corrected information and sent it over to C&I engineering to update the master ETAP model.

This study is…

This study is important because it helps us model arc flash exposures and predict the incident energy that would be released.

This also helps…

This also helps us evaluate our distribution system, determine weak points, and prepare against potential arc flash incidents.

I learned that…

I learned that the purpose of maintenance mode is to increase the sensitivity of the settings on the protective relay in order to decrease the operational current and reduce the incident energy, which also limits us from operating normally.

If we were…

If we were start up while maintenance mode is enabled, we would encounter false trips since the current would not be sufficient enough, which is a reason why maintenance mode is considered to be a temporary solution in terms of arc flash mitigation.

Overall, this project…

Overall, this project taught me the importance of electrical coordination as an essential tool to prioritizing personnel safety while keeping critical equipment running.