175Z7371 by Danfoss

The 175Z7371 is an HVAC variable frequency drive from Danfoss in the VLT 6000 HVAC Drives series. Designed for industrial and commercial air-handling installations, the unit regulates three-phase motor speed to maintain airflow, water circulation, and pressure in building automation systems. By adjusting output frequency instead of relying on mechanical throttling, it supports efficient operation across the normal load range and helps reduce motor inrush current and wear during repeated starts. In variable-air-volume and pumping applications, that control helps match motor output to changing demand instead of keeping equipment at full speed.

It delivers a continuous power capacity of 45 kW / 60 hp, allowing it to start and run medium-sized pumps or supply fans directly from the mains. The drive accepts a supply window of 380-460 VAC, which covers common 400 V distribution networks used in HVAC plants. Its housing is classified as Compact NEMA 1, so the electronics are protected from incidental contact and settled dust when mounted in mechanical rooms. Parameters can be programmed through the front-mounted interface supplied with an LCP, which removes the need for a separate keypad during setup and routine adjustment. Because the circuit boards have no conformal coating, the drive should be installed in a clean, noncorrosive environment to reduce the risk of moisture-related tracking.

The power section is built as a standard unit. Factory configuration uses the Graham application profile, which loads control behavior suited to constant-torque fan service. All communication slots remain empty because there is no fieldbus option, so networked control requires separate hardware outside the base unit. The cabinet ships without an RFI filter, so an external line filter is required where local codes limit conducted emissions. This arrangement supports local motor control in conventional building panels where communication and filtering components are added separately when needed.