175H8858 by Danfoss

The 175H8858 is an AC variable-frequency controller produced by Danfoss within the VLT 3000 Variable Speed Drives series. By adjusting the stator frequency delivered to a three-phase induction motor, this drive regulates speed and torque so that pumps, fans, and conveyors run only as fast as the process demands, reducing energy use and mechanical wear in industrial automation cells. It is intended for applications that need adjustable motor speed without relying on fixed-speed operation or mechanical throttling.

The control section will accept mains that fluctuate by up to ±10%, allowing installation on feeders that experience modest voltage swings. Internally, it is sized for motors up to 2.2 kW, and its output stage can supply a continuous line current of 4.8 A at the terminals. That current is synthesized as a PWM waveform tracked to the motor's synchronous speed reference of 60 Hz. To match driven load requirements, the first acceleration profile, Ramp 1, reaches setpoint in 5 s. This short rise time helps limit inrush current while keeping the process responsive. During operation, the input side draws a maximum of 4.8 A, so conductors and protection devices can be selected for similar thermal loading on both the line and load sides.

When a stop command is issued, Ramp 1 decelerates the motor over 5 s, helping prevent torque shocks to couplings and gear stages. The recommended supply-side overcurrent device is rated at 16 A, coordinated with the converter's trip threshold to clear faults without nuisance interruptions. Field wiring enters cage terminals that accept up to 2.5 mm² stranded copper, providing enough cross-section for the stated current while fitting standard conduit glands. Command logic should observe the manufacturer's duty recommendation of 1 time/min on the switching input. Following that switching rate helps avoid excessive thermal cycling in the power section and keeps drive response consistent.