Are Armstrong Variable Speed Booster Systems designed to auto-start after a power failure?
Yes, this feature is standard. For both emergency backup power and non-emergency power system, the system will go down and resume automatically once power is resumed – no resetting is required. However, there could be a snag if the VFD’s are not properly set up. Once power fails, the VFD’s will generate an internal alarm ‘low bus fault’ due to the inability to keep the capacitor bank charged. Most VFD’s will remain powered, operating from the depleted capacitor bank for up to 30 seconds once power fails. If power is resumed within this time prior to the VFD completely shutting down, it is quite possible for the VFD to ‘trip out’ on alarm. For this reason we set the drives up to have automatic restarts (generally set to 5 but could be set higher with a 30 second interval between attempts).
