Torque Motors

Torque Motors type 1 LN3 have been specially developed for certain applications where standard squirrel cage induction motors can not be used. They are ideally inertia loads with frequent start/stop/reversal. 

Special Features : Designed to give linear torque-speed characteristics

The special features of the characteristic are as under.

1. The starting  current is approximately 50% of that of a standard motor, for a given starting torque. For applications involving high number of starts/stops/reversals, thermal stress on motor windings  is therefore much less in case of Torque motor. Because of the same reason, these motors can also be used for applications requiring operation under stalled or locked rotor condition for extended/continuous period with a specific stalled torque value.

2. As torque is maximum during starting and reduces linearly with speed increase, there is no unstable region in the characteristic. This enables, the motor to operate at all speeds from zero to full speed.

3. Because of low starting current for a given starting torque, these motors can be generally offered in lower frame sizes when compared to squirrel cage motors for specific applications. The low starting current makes them suitable for applications involving frequent starts.

Typical applications Wire Winding Machines 

In wire winding machines, the load has a rectangular hyperbolic characteristic. For a limited range, the torque motor characteristic approximates a rectangular hyperbola closely enough to satisfy winding application requirements. The requirement of constant tension and constant linear velocity can therefore be satisfied by torque motor. 

Fast Tapping Machine   

Single or double speed motors required for fast tapping machines have plug reversal rates as high  as 15 to 20 Nos. per minute.

Due to this heavy plugging, thermal stresses develop on the motor winding. The actual load torque for tapping is very small and is only for short duration in each cycle. Due to relatively very low starting currents, torque motors are again the right choice for such applications.

In Roller Conveyor Applications 

In steel rolling mills, the ingots are rolled into sheets by passing them through main rollers in successive operations. This is done by moving ingots to and fro on roller conveyors at a very high rate. A Torque motor is an ideal drive for these conveyors due to the following duty conditions:

1. The motor is required to rapidly accelerate high inertia rollers to rated speed.

2. The load torque is only the frictional torque which is very small.

3. The rate of reversing is very high.

Variable Speed Drives

Since there is no unstable region on the torque speed characteristics of a torque motor, it can be made to deliver the desired torque at any speed between zero to almost full speed, by controlling voltage.

Clamping/Positioning/Indexing Devices 

In various machine tools the jobs to be machined are required to be clamped positioned/indexed. The clamping, positioning or indexing machine can be electrically operated by a motor which is required to remain continuously under locked rotor condition. Torque motors can be offered for such applications.

Other Miscellaneous Applications.

Product Range

1. Frame sizes : Available in IEC frame sizes 63 to 160 L

2. Type of Enclosures : Standard motors are supplied in TEFC, IP54 enclosure. Other types of enclosures can be also offered.

3. Types of Mounting : Standard motors are supplied foot mounted. Other types of mounting can be also supplied.

4. Operation Specifications : Standard motors are suitable for operation at following conditions :

          a) Voltage : 415 + 10%

          b) Frequency : 50 Hz + 5%

          c) Ambient Temperature : 40 C

   
    5    Built-in-Brakes (optional)

          These motors can also be supplied with built-in brakes for applications, where, in addition to the requirement of special Torque Speed Characteristics, fall safe brake operation is also required.

    6.   Dimensions

Torque motors are offered in standard IEC frames, and the overall dimensions are the same as those of squirrel cage motors type 1 LA3

Enquiries and Orders

In your enquires or orders, please furnish the following information :

Applications Engineering Service

our engineers are always available without obligation to study and advice our customers on any individual applications, so as to make the best choice to suit specific requirements.