Korea Ever-Power · YS Series · Small Power Light Industrial Drive Guide

Single-phase motors below 750 W typically use run capacitors to create the phase shift needed for starting and running torque. These electrolytic capacitors have a service life of 3 to 7 years in continuous industrial service and are the most common failure cause for small single-phase motors. A failed run capacitor causes the motor to draw high current, overheat, and either trip the overload or fail the winding. The YS three-phase motor has no capacitors — its squirrel-cage rotor requires no starting or running capacitor and produces full torque from a three-phase supply without additional components.

Three-phase squirrel-cage motors have significantly higher efficiency than equivalent single-phase capacitor-run motors at the same power rating. A single-phase 370 W motor typically runs at 65 to 72% efficiency; the YS 370 W three-phase motor runs at 75 to 82% efficiency — a saving of 10 to 17% in power consumption for the same mechanical output. Over 8,000 hours per year at an electricity tariff of $0.13/kWh, the energy saving from switching to three-phase at 370 W is approximately $65 per motor per year — more than the cost difference between the motors in under 2 years.

Single-phase motors have very high starting current — typically 5 to 8 times rated current — which can cause voltage dips on the supply circuit that affect nearby sensitive equipment. The YS three-phase motor starting current is 4.5 to 6 times rated across three phases, and the supply current draw per phase is lower than a single-phase motor of equivalent power because the power is shared across three conductors rather than concentrated in two. This reduces voltage drop at machine startup and eliminates the flickering on nearby lighting that single-phase motor starting can cause.

The squirrel-cage three-phase motor has no brushes, commutator, starting relay, or run capacitor — the only wearing components are the bearings. With correct bearing selection and lubrication, the YS motor service life is 15 to 25 years in light industrial service, compared to 5 to 10 years for a typical single-phase motor with equivalent maintenance. This longer service life reduces the total cost of ownership of the drive system despite the potentially higher initial motor price.

Triac speed controllers for single-phase motors produce significant RFI that can interfere with PLC inputs, sensors, and communication equipment in the same panel. A micro-VFD on a YS three-phase motor produces much less RFI (particularly when the VFD output filter is fitted) and provides smooth torque from zero speed, whereas a triac controller loses torque at low speed because the motor cannot produce adequate torque at reduced voltage on a single-phase supply. The VFD-YS combination maintains full motor torque down to approximately 10% of rated speed.

A micro-VFD driving a YS motor provides 0 to rated speed (0 to 50 Hz) with linear torque capability throughout, and can be programmed for acceleration and deceleration ramps to eliminate mechanical shock on startup. This combination is ideal for: screen printing table drive with adjustable squeegee speed; textile winder with adjustable tension; agricultural feeder with rate adjustment from operator panel; and laboratory stirrer with calibrated speed display. A single micro-VFD can drive any YS motor in the 25 W to 750 W range, providing a standard control platform for multiple drive sizes.

The Korea Ever-Power YS series is the small-power three-phase motor range for light industrial applications below 750 W. It uses the same IEC 72-1 metric frame system as the full Y2 series, making it compatible with all NMRV gearboxes and standard industrial motor accessories (flanges, couplings, footplates). The YS is available in 4-pole as standard (approximately 1,350 to 1,430 rpm depending on power size) with 2-pole and 6-pole options for applications requiring higher or lower speed. The complete YS range is in the small power motor product section. Contact Korea Ever-Power for custom shaft, flange, or mounting configurations for OEM machine builders.

Laboratory tumble dryers, analytical sample rotators, slow-speed centrifuge drives, and instrument drive tables use YS 25 to 180 W with NMRV gearbox. Very quiet, no brush noise, no RFI — essential in laboratory environments where analytical instruments are sensitive to electrical interference.

Short conveyor sections (1 to 3 m) for parts transfer in assembly areas, light packaging conveyors in retail environments, and museum display or retail shop moving display fixtures. YS 60 to 370 W with NMRV at 40:1 to 80:1 for slow display movement at 5 to 20 rpm output.

Centrifugal pumps for small process flows (10 to 50 L/min), air blowers for drying and cooling in light industrial processes, and water circulation pumps in small laboratory or process systems. YS 250 to 750 W direct drive at 1,400 to 2,800 rpm depending on pole count. Higher efficiency than single-phase at the same flow duty.

Metal lathe headstock drive, bench grinder, column drill, and wood lathe in three-phase workshops. YS 370 to 750 W provides higher starting torque and better speed regulation under cutting load than equivalent single-phase motors, improving machined surface quality and tool life in light precision work.