Why one should go for soft starter :-
1) To reduce starting current / electrical stresses of motor & system.
Reduced current enhance the life of the motor as well as system.
2) To start the motor with reduced current on limited power source with base load.
Low starting current reduces the starting KVA demand which can help to start motor on limited sanctioned capacity & without interrupting the base load.
3) To start the motor on limited size of transformer / generator with base load.
Due to increase in base load / plant load / change in the motor rating, starting with reduced current will reduce the starting KVA & will help to start on existing transformer / generator.
4) To select the correct size of transformer / generator at the initial stage of project.
Selection of correct size of transformers / Generators (for starting as well as running load) is quite engineering task. Selection of high size may leads to non-utilization of the capacity & adds to high initial & running cost. And selection of low capacity may result in overloading the same.
5) To limit the voltage drop on system.
• Voltage drop during starting leads to nuisance tripping of other plant loads due to under voltage.
• In Generator, voltage boost after acceleration of motor due to sudden drop of the current as AVR response is not enough fast. So it may trip either on OV or will generate problems related to OV.
6) To reduce / eliminate the mechanical shock to avoid the mechanical damages of equipment.
Because of high torque with 100% voltage it may leads to twisting / bending of shaft, breakage of foundation bolts, mechanical damages to impeller / blades etc. of driven equipment, related damages / loss of product.
7) To avoid / reduce motor / rotor burning problem due to hotspots in rotor bar during starting for certain typical applications.
Due to prolonged acceleration & consecutive starts at DOL , I2t losses are comparatively high & there is no enough time to spread the heat in complete rotor body. This may lead to hotspots which lead to failure of rotor bars.
1) Study the requirements.
2) Study the problems.
3) Study the system & application.
4) Calculation of minimum possible starting current & acceleration time.
5) Checking the thermal curve of motor for starting purpose.
6) Calculation of voltage drop if required.
7) Suggest our suitable starter model to satisfy the actual requirement of customer.
1) The actual requirements / needs of customer.
2) The problems.
3) Why the problem exist?
4) What are the causes of the problem?
5) Will Soft Starter helps on observed problem?