Technical note on Slip dependent Rotor Starters:

Slip dependent Rotors starts works on variable resistance directly proportional slip intern to load. (Resistance α Slip α Load).

STARTING:While starting Motor requires high starting torque to drive very large inertia drives like CaneFibrizer, Chopper and Levelers.

• To achieve this high starting torque one has to introduce high resistance in to rotor circuit of Slip Ring Induction Motor.(SIM). At the time of starting the slip is Unity    (Maximum) hence our Rotor starter will offer maximum Resistance, achieve the maximum torque.
• As Speed increase towards rated speed,to maintain high motor torque delivered at all speeds, one has to reduce the rotor resistanceaccordingly, as speed increase    the slip reduces hence our Resistance will also reduce, so that we could ensure Motor delivers constant maximum torque at all time of traveling from zero speed to   rated speed.
• Motor acceleration is smooth, step less and jerk less. Since resistance reduction is step less and automatic.
• Automatic Zero-speed sensing and offering high value of resistance at start. Thus avoid motor damages.

RUNNING:During running at the instant of sudden quick load due to uneven raw material feeding there will be sudden torque demands from motor results in current kicks, which may be more than 150%, also the reduction of speed. To overcome this one can introduce resistance in rotor circuit to limit current kicks and to shift motor operating point to maximum position on T_N curve during sudden loads. As standard practice in industry there will be fixed buffer resistance which alters motor T_N characteristics such that motor operating point will be at maximum torque condition always, irrespective of kick loads. This leads in increases loss due to the operating slip increased and also due to the fixed buffer (any one can observe fumes)more losses dissipating in terms of heat.

With our system we introduce impedance in the rotor circuit,which value is inversion to the motor speed(at high speed-rated speed resistance minimum and lower speed due to the kick loads –high resistance hence limits current kick and motor deliver maximum torque with respect to that speed.). Factitious Resistance values of our Dynamic Buffer Resister are dynamic in nature with very less response time(almost instantaneous).

By introducing the dynamic resistance which is proportional to slip, we could save the energy up to 8% of the motor power, comparatively which was lost in case of fixed 15% buffer.

Applications :

This type of loads appear normally

Sugar industry - Cane Fibrizer , Cane chopper ,Cane leveler

Cement industry - lime stone crusher

Paper industry - Wood chopper , pulp grinder

Salient Features:

• Slip dependent Resistance provides automatic resistance variation.
• Low Starting current.
• High starting torque.
• Built in bypass contactor.
• No moving parts &stepless cutting of Resistance.
• No maintenance.

ELTECH ENGINEERING: For Slip Ring Induction Motors -

Automatic Rotor resistance Starters (ARS)For Slip ring Induction motors –Starting.

We provide ARS Starters for Slip ring induction motors, which connected in rotor circuit.

Range: 0.5 KW/415 V to 6,000 KW/3.3 KV, 6.6 KV, and 11 KV.

Application: For All Slip ring Motors.

Technical note on Slip dependent Rotor Starters:

Slip dependent Rotors starts works on variable resistance directly proportional slip intern to load. (Resistance α Slip α Load).

STARTING:While starting Motor requires high starting torque to drive very large inertia drives like CaneFibrizer, Chopper and Levelers.

• To achieve this high starting torque one has to introduce high resistance in to rotor circuit of Slip Ring Induction Motor.(SIM). At the time of starting the slip is Unity    (Maximum) hence our Rotor starter will offer maximum Resistance, achieve the maximum torque.
• As Speed increase towards rated speed,to maintain high motor torque delivered at all speeds, one has to reduce the rotor resistanceaccordingly, as speed increase    the slip reduces hence our Resistance will also reduce, so that we could ensure Motor delivers constant maximum torque at all time of traveling from zero speed to   rated speed.
• Motor acceleration is smooth, step less and jerk less. Since resistance reduction is step less and automatic.
• Automatic Zero-speed sensing and offering high value of resistance at start. Thus avoid motor damages.

RUNNING:Our rotor starter will be out of circuit with the help of inbuilt bypass contactor and during running motor will be acting as Squirrel cage induction motor(Rotor circuit made star with no external resistance.)

Applications :

This type of loads appear normally

Sugar industry - Pumps, some application required high torque.

Cement industry - Ball mills, wagon un loaders ,cement mills

Steel industry - Ball mills

Salient Features:

• Slip dependent Resistance provides automatic resistance variation.
• Low Starting current.
• High starting torque.
• Built in bypass contactor.
• No moving parts & stepless cutting of Resistance.
• No maintenance.