This free calculator helps engineers, technicians, and panel designers quickly size VFDs, Soft Starters, brake resistors, and enclosures in line with U. Find the right drive in minutes. Enter motor data to get size, current, and ROI instantly. The IEC standard for softstarters is called IEC 60947-4-2 and softstarters built according to this standard are in most countries not subject to any other tests besides th manufacturer responsibility. In some countri he CE marking on the product. During starting, these devices limit the torque as well as the current and prevent the shocks whic arise during direct starts or wye-delta starts. In this way, mechanical load efore longer periods of trouble-free production. You'll need to evaluate: Each factor affects which unit survives the application long-term.