Applications of Industrial Drive

Applications of Industrial Drive > TRAVELLING CRANES:

Both AC and DC drives are used for the different operations in a crane. The preferred drives on consideration of economy end utility are indicated below:

Operation	Type of drive
(i) Hoisting and lowering	AC slip ring motor. Ward Leonard . controlled DC shunt motor and DC compound motor.
(ii) Crane travel	AC slip ring motor.
(iii) Trolley travel	AC slip ring motor.
(iv) Slew and swing action	AC slip ring motor or DC shunt motor.
(v) Boom hoist	AC slip ring motor.

DC motors are used for load hoisting and lowering where smooth, precise and at the same time fast speed control is required as in the case of cranes used in steel plants, power houses and concrete dams.

Applications of Industrial Drives > ROLLING MILL DRIVES:

The following types of drives are used for rolling mills:
(i) DC motors,
(ii) AC slip ring motors with speed control.



The DC motors, because, of their inherent characteristics, are best suited for the rolling mills. Speed control is effected either through Ward Leonard system or by grid controlled mercury arc rectifiers. AC slip ring motors are suitable for roughing and re-rolling mills where very precise speed control is not required Their efficiency is low because of the power wasted in the rotor resistance. There is also abrupt rise in motor speed when the material leaves the rolling stands.

Applications of Industrial Drive > KILN DRIVES:

Call for a starting torque of about 250% in addition to the speed control feature. The commonly used drives are:


(i) Slip ring induction motor
(ii) Three phase shunt wound commutator motor
(iii) Cascade controlled AC motor
(iv) Ward Leonard controlled DC motor
(v) DC motor with transformer step switch control.

Applications of Industrial Drive > TEXTILE INDUSTRY:

The textile industry requires special types of drives for
(i) weaving, and
(ii) spinning.

(i) Applications of Industrial Drive > Weaving:

The motors used in weaving mills must have good cooling capacity to keep their temperatures within limits in the presence of large power losses. The rating of the motors and the cooling facility must be properly selected, because these motors are used in conditions where high moisture content is present along with lot cage induction motors with high rotor resistance, totally enclosed, fan cooled and having high temperature insulation are used to drive looms. For light fabrics like cotton, silk, nylon etc. small motors of less than 1 hp may be sufficient. For heavy fabrics such as wool, the rating of these motors may be 2-3 hps. These motors are normally run at 750-1000 rpm.

(ii) Applications of Industrial Drive > Spinning:

The spinning mills use one of the following three types of drives:
(i) A 4-pole or 6-poIe squirrel cage induction motor,
(ii) A pole amplitude 4/6 or 6/8 poles induction motor,
(iii) Two separate motors to be runs at 1500/1000 or 1000/750 rpm. But whatever may be the types of motor used, the motor must be started with controlled torque.

Applications of Industrial Drive > PAPER INDUSTRY:

In a paper industry, the drives are required for
(i) Pulp making, and
(ii) Paper making.

In the pulp making process, the logs of wood are either ground in mechanical grinders or else they are chemically treated with alkalis and simultaneously beaten up to turn them into soft pulp. In the mechanical method of pulp making, the electrical power requirement is very high because the wood is hard. Since the mechanical grinders operate at a constant speed of about 200-300 rpm,the motors can be started on no load. Thus synchronous motors are used for these drives. These motors normally run at 1000-1500 rpm and gears are used to reduce the speed to 200-300 rpm.

In the chemical method of pulp making, the logs of wood are continuously beaten by the beaters at the time of treatment with alkali. The power requirement of the beater motors is less than those of grinder motors but these motors require high starting torque. Therefore, slip ring induction motors with gears are used to drive these beaters at about 150-200 rpm.

Applications of Industrial Drive > BELT CONVEYRS:

Normal starting current, high starting torque (double cage) squirrel cage motors with direct-on-line starters are used for conveyr drives because they have often to start with full load.

Applications of Industrial Drive > Compressors:

Wound rotor induction motors and synchronous motors are generally used on large size machines. Squirrel cage motors are used for small compressors only.

Applications of Industrial Drive > Blowers-fans:

The squirrel cage induction motors and synchronous motors are used for driving blowers and fans.

Applications of Industrial Drive > Pumps:

Centrifugal pumps are driven by squirrel-cage induction motors or synchronous motors. Reduced voltage starters can be used because of low starting torque requirements.

Applications of Industrial Drive > Machine tools:

Squirrel cage motors are normally used for them.

Applications of Industrial Drive > Jaw crushers:

Belted slip ring induction motor is almost invariably used as, very often, the motor has to start against heavy load or a stuck crusher. Pipe ventilated motors should be used so that supply of cool and clean ventilating air can be ensured even industry dusty atmosphere.