175H3137 by Danfoss

The 175H3137 is an AC variable frequency drive produced by Danfoss within the VLT 3000 Variable Speed Drives series. In automated plants, this unit modulates the voltage-to-frequency ratio supplied to induction motors so that conveyor lines, pumps, or fans can match their speed to process demand instead of running at a fixed mains frequency. By converting a three-phase input into a pulse-width-modulated output, the drive provides a compact alternative to mechanical throttling or gearbox changes.

The digital control core resolves commanded frequency changes to 0.05%, allowing fine speed trimming during closed-loop regulation. When rapid acceleration is required, the inverter can deliver up to 500 Hz at its output terminals, extending motor speed well beyond the normal 50/60 Hz range. Power draw on the supply side is characterized by two input current ratings: 13 A for constant-torque duty and 17 A for variable-torque duty. These values guide cable sizing and upstream protection. Under constant-torque loading, the converter is rated for 9.3 kVA of apparent power, a figure that combines true power and reactive components delivered to the motor windings without power-factor correction hardware.

For variable-torque applications such as centrifugal pumps, the apparent power capacity rises to 11.5 kVA. Corresponding output currents are 13.0 A in constant-torque mode and 16.0 A in variable-torque mode, so the same frame covers two distinct loading profiles without derating. Shaft power follows the same pattern, reaching 5.5 kW in constant-torque service and peaking at 7.5 kW when the load type allows torque to fall with speed. An integrated RFI filter attenuates conducted emissions to help the panel meet EMC limits, and the design limits start-stop cycling to one switching action per minute to protect its DC-link capacitors from repetitive inrush stress.