Home Forums General Discussion Technical Questions Emergency Power Question

When the building switches from emergency power back to normal what is a normal delay time? I did some testing in one of my buildings last night. The timer was set at 45 mins on the transfer back to normal. This seemed a little excessive. Am I in the wrong here. Seems like most buildings I have done testing in 15 mins was the longest I ever had to wait. The building engineer and electrician had no idea how to shorten the timer. Those two didnt know alot of things.

I thought 10 minutes was the norm...

Are you talking about the amount of time the generator runs, the amount of time the transfer switch stays on the 'emergency power' side, or the amount of time it takes to transfer the cars from emergency power to normal?

Just wanted clarification. I've spent alot of time at buildings over the years sorting through emergency power issues, and don;t want to answer incorrectly and cause confusion.

the delay time is field adjustable, for however long you wish to run the emergency generator.15 -30 minutes is normal, it depends on how much fuel you wish to burn while testing the backup power.

Going from em power back to normal. I had to wait 45 mins to recieve the presignal so my equiptment will switch back.

Way too long. This can be as little as fifteen seconds as far as your elevator is concerned. You only need enough to get to a floor and complete a door open cycle. If the other equipment in the building is computer controlled and needs time to shut down critical functions like in a hospital well then..... whatever they want. Bill them for this testing time and take a book.

so the backup generator was running for 45 minutes, correct. that time is what the electricians programed the Generator to excersize during a test cycle. It is fully adjustable. The actual switch time to go from Normal to EM and then back to Normal is the amount of time to get to the nearest floor and park with the doors open. This time is the power change pending signal or the pre signal, it is usually 15 or 20 seconds.

Depends on the transfer switch timing. That's the buildings stuff. They want to make sure before a transfer that all IR has collapsed on the supply side and the current is 0 before the transfer from NP to EP or vice versa.