Product Description:

The 135U3977 is a variable-frequency HVAC drive built by Danfoss for the VLT FC 102 HVAC Drives series. It regulates motor speed in air-handling units and chilled-water pumps so building systems can follow changing demand more closely. That control helps maintain comfort while reducing energy use during part-load operation.

The power section is sized for a continuous input of 634 A, allowing the controller to energize large three-phase motors without derating. A shaft output of 355 kW, equivalent to 500 HP, supports high-capacity ventilation and cooling duties in commercial facilities. The rectifier and inverter are designed for mains supplies between 380 to 480 VAC, which gives the drive flexibility across common low-voltage utility systems. When the incoming line is near the lower end of that range, the inverter can deliver up to 724 A at its output terminals to support demanding starts and acceleration.

An 110% overload for 1 minute every 10 minutes lets the drive absorb short demand increases caused by filter fouling or shifting valve positions without tripping immediately. The electronics are housed in an IP20 chassis intended for clean control cabinets where fingertip protection is adequate. Operating losses are limited to 6928 W, so enclosure ventilation must remove that heat during continuous service. An integrated RFI filter reduces conducted high-frequency noise and helps installations meet EMC requirements without extra external components.

Wake Industrial can arrange same-day shipping on urgent orders. Each purchase includes a 1-year warranty. International shipping options are also available to buyers outside North America.