GYKCWD NSAP-DLA-3-Repairing Cooling Tower VFD Unit

This project is to repair the cooling tower Variable Frequency Drivers (VFDs) in the B3 3C mechanical room in front of chiller #2. The VFD controlling the fan motor for Cooling Tower #1 (located on the South Side) is currently inoperable in Auto (AFC) mode according to a handwritten site note. The issue appears to have been going on since at least 2017 based on the dates written on the note. A photo of the note along with other photos of the cooling tower are attached to this form. The drive trips at 60Hz whenever it's in AFC mode thus requiring it to be kept in Bypass Mode to remain running. In Bypass Mode, the fan operates at full speed without modulation which is less energy efficient and more stressful on the mechanical components. Proper functioning of the VFDs is critical for cooling tower performance and energy efficiency. Corrective repairs or a full unit replacement is recommended A site inspection found that the VFD display shows "nSt" (Not Started) status indicating that the drive is powered but not running. A photo of the display is attached. The VFD is a Telemcanique with a model number of ATV31HD11N4A. It is rated for 11kW / 15 HP. It's input and output voltage are 380-500V and 380-600V respectively. It is connected to Panel - P1 - 5, Breaker - 15. A photo of its specifications is attached. 7. If the drive cannot be restored to functionality after troubleshooting, replace the VFD entirely with a new unit. DATE SUBMITTED: 8/8/25 TF-1#DLA-FY25-032