Fig 1

A conventional means of limiting the start-up currents of the phase-wound rotor induction motor is introduction of starting resistors (fig. 1) into the rotor circuit. The disagvantage of this method is the existence at the moment of transit from one mechanical characteristic to another resulting in the failure of the drive's mechanical and electrical parts.

The solution of this problem the Kirov lifting magnets plant DimAl, Ltd. sees in the use of adjustable current-limiting reactor electric drive consisting of the DPP-series starting current-limiting reactorÏ and the DRS-series thyristor rotational velocity regulator.

This type of a drive excludes active resistors control systems from the rotor circuit and has the following advantages:

1. Ensures smooth start and braking of machinery.
2. Excludes changes in both the current and motor's moment. This feature improves the operational reliability of the electric motor and other mechanical parts, such an improvement leads to the lengthening of the machinery's life-time.
3. allows to limit both the starting current and moment without use of additional control systems. The values of the starting current and moment, the acceleration and braking intensity determined by the number of starting current-limiting reactor's coils are set at fettling and remain unchanged for the starting reactor's life-time.
4. Ensures smooth or stepped adjustment of the rate of revolution in the range of from 10% to 100% of the nominal rate.
5. Compact, easy to set up and to service.
6. The use of this drive allows to get rid of up to 50% of other electric equipment and cables, to cut depreciation costs. It also lowers the drive's price and reduces the volume of wiring operations.
7. Saves electric power.

Power range (series manufacture): from 1.4 kWt up to 160 kWt.

Operational ambient air temperature range: from - 40°C to + 60°C.

Fig 2 - current-limiting reactor electric drive's wiring diagram

Fig 3. Mechanical characteristic of a reactor electric drive