175L3718 by Danfoss

The 175L3718 is an AC variable frequency drive manufactured by Danfoss for the VLT 3000 Variable Speed Drives series. As a closed-loop speed controller, it receives three-phase mains power, modulates output frequency, and regulates induction motors in conveyors, pumps, and fan assemblies. By controlling motor speed rather than relying on mechanical throttling, the unit helps automation systems match torque to process demand and reduce power dissipation. Closed-loop control also helps the drive correct speed changes caused by varying load conditions. Digital parameter sets allow users to tailor current limits, braking modes, and I/O logic to specific machine requirements, and its programmable ramps can coordinate acceleration with broader process sequences.

At full load, the drive operates with an efficiency of 0.96, so only 4% of the input energy turns into internal heat. It delivers 125 HP and a continuous output current of 168 A, while supporting a maximum output frequency of 120 Hz for overspeed tasks. When the supply voltage varies within ±10 %, regulation remains stable, and apparent demand can reach 116 kVA. The silicon-controlled rectifier front end conditions incoming three-phase power before the IGBT bridge generates the commanded output frequency. The ambient limit is 40 °C, and an overload window of 185 A for 60 s accommodates torque surges during acceleration.

For protective coordination, the mains circuit is backed by a 250 A pre-fuse, and the drive can draw 167.2 A at peak. The programmable ramp time extends to 3600 s, which helps reduce mechanical shock on large-inertia loads during starting and stopping. Cable runs may reach 1000 ft unshielded with a 500 kcmil cross-section. The unit tolerates 0.7 g vibration and sheds 910 W of heat at maximum load. It is housed in a NEMA 1 enclosure and weighs 464 lb, which supports panel mounting in indoor cabinet applications.