YVF2 variable-frequency motor

The published operating sketch shows torque declining above the base-frequency transition. As an engineering relationship, if mechanical power remains constant while shaft speed doubles, torque halves. That arithmetic explains the trade-off; it is not a promise that every listed motor may double its speed. In particular, the stated two-pole and 355-4 limits are lower than 100 Hz.

The introduction describes an external cooling fan and an S1 continuous rating, with 380 V, 50 Hz, class F insulation and IP55 enclosure protection. A low-speed continuous-load order needs the fan supply, cooling arrangement and operating interlock specified along with the main motor. Do not assume the fan can be fed from the variable-frequency motor terminals or that a stopped fan preserves the stated continuous-load envelope.

The four 4 kW examples span 8.31–10.2 A even before considering application overload. Their rotor inertias also differ substantially. Supply the inverter vendor with the exact motor current, rotor and reflected load inertia, required acceleration, reversing frequency and braking duty. Selecting an inverter only because its label also says 4 kW leaves those differences unresolved.

The 4 kW eight-pole example has a listed L of 660 mm, compared with 480 mm for the two- and four-pole examples. Verify the delivered fan cover, terminal-box access, mounting form and shaft drawing against the machine. The catalogue’s outline sketch and length table do not alone prove that an existing standard motor can be replaced without bracket or coupling changes.

Give the required minimum continuous speed, maximum running speed, torque at each, ambient conditions and acceleration or deceleration time. Ask for confirmation against the exact YVF2 or YVFE2 nameplate and the proposed inverter settings. The catalogue’s locked-rotor and maximum-torque ratios are separate characteristics, not continuous torque permissions throughout the frequency range.