Does the Equipment ATS fall into the 10 second max start up time frame?
Given that the VFDs need to ramp down before coming back up to avoid over voltage and damage to the motors.
Good morning Mark,
I am trying to visualize your application based on your question and I would like to better understand the system configuration.
I am assuming that the VFD's and driven motors you refer to are fed from a MCC or other distribution equipment that is provided a secondary power source via an automatic transfer switch.
From which standard or other document are you getting the "10 second max start up time frame"?
The shutting down of the equipment or motors and/or motor re-starting is coordinated through what type of process?
So this is a Hospital, Life safety and critical care are required to transfer from normal to generator power in 10 seconds or less in a loss of power situation, but because of the nature of our system where the RTUs, hot water pumps are controlled via VFDs, then having such a quick transfer of power back to the VFD does not allow them to power down and can be detrimental to the motors causing over voltage when they come back up too quickly.
NFPA 101(00), Sec. 18.104.22.168 requires that emergency loads be picked up within 10 seconds.
Mark S. Hey
8515 W. Coal Mine Ave,
Littleton, Colorado 80123-4429
SCL Health Aurora
23770 East Smoky Hill Rd,
Aurora, Colorado 80016
Mark, I better understand your original question now. I am not an electrical engineer nor do I have much experience in critical care power systems. However, in my industrial experience I think there may be a solution to your concern. I am not sure whether your emergency source is diesel, electric or perhaps a combination of both, this would affect the results somewhat. (Diesel being unavailable longer that electric) If there were a transitional power source between emergency and normal and the VFD parameters were optimized so that the motor saw very little sag or swell...the coordination of the emergency equipment/transitional equipment and VFDs should provide a solution.
Retrieving data ...