175L2039 by Danfoss

The 175L2039 is an AC variable frequency drive produced by Danfoss as part of the VLT 3000 Variable Speed Drives series. Designed for cabinet installation, the unit modulates the voltage and frequency supplied to a standard induction motor so that conveyor, pump, or fan speed follows process demand. In industrial automation, this reduces energy use, limits mechanical stress, and allows closed-loop torque control without additional mechanical gear sets.

The input side accepts a 3×440/460/500 V (±10%) power supply connection across three conductors, and operation is synchronized with line cycles at 50/60 Hz. Because the power circuit is configured for a three-phase source, current is distributed evenly across the phases to help minimize harmonics. Under constant-torque duty, the inverter can deliver 27.9 A of fundamental output current and up to 38.6 kVA of apparent power to the motor terminals. Overall conversion efficiency is 0.96 at rated load, so only four percent of incoming power is lost as heat. A built-in electronic thermistor monitors the motor windings and triggers trip functions when temperature rises beyond set limits, providing thermal protection without external overtemperature relays.

During variable-torque applications such as centrifugal pumps, the drive limits phase current to 24.2 A, yet it can still produce a mechanical output of 15.0 kW at the shaft. The power stage synthesizes carrier-based PWM up to 500 Hz, allowing high-speed spindles or multi-pole motors to run above base frequency when process requirements call for a wider speed range. An overload window permits 44.6 A for sixty seconds so brief acceleration peaks do not cause nuisance trips. The control terminals impose an input start/stop limit of one initiation per minute to protect the precharge circuitry and extend capacitor life.