The FCMA Soft starter achieves this through a unique system of flux compensated non saturated magnetic amplifier for controlling the motor current and hence the motor torque during acceleration. The Flux compensated magnetic amplifier (FCMA) is an antithesis of the saturable core reactor. The FCMA works on the principle of flux opposition instead of flux addition & hence operate always in the linear nonsaturable zone of the magnetic circuit.
The AC induction motor with a permanently coupled load, when it is operated without the benefit of a soft starter draws a high starting current. Typically, more than 7 times it’s rated full load current. “Reduced voltage-starting decreases the demand”. A Soft starter makes use of this principle.
The soft starter can meet such requirements. In pumping station, soft stop technology can avoid the pump door damaged of the pumping station, to reduce maintenance costs and maintenance works. The soft stop function in soft starter is, when the thyristor gets stop instruction, decrease conduction angle gradually from full conduction, and achieve full closed after a certain time. Stopping time can be adjusted according to actual requirements within 0 - 120s.
The advantages/disadvantages of different types of motor starters like DOL, star/ delta, korndorfer, primary resistance/reactance, shunt capacitance, slip ring, vfd, vsd, auto transformer etc.DOL (simple start up but reflect to high voltage drop, high starting current, low starting period duration)less power saving.star/delta decrease the starting current to 1/3 but required many relays for control change between start connection then to delta.
There are many variables that will govern the run up time of the motor. It's not uncommon to start the motor/pump of this rating DOL provided you've ensured that the voltage drop at the bus from where it is fed is within the limits. We presume, you've carried out the motor starting study with your other base load ON and established the Voltage drop at the bus.
Soft starters and variable frequency drives are two completely different electric devices. Variable frequency drive is used for AC motor speed control, it can change output voltage and frequency at the same time; actually, soft starter is a regulator for motor starting, only changes output voltage but not the frequency. Variable frequency drive has all the features of soft starter, but its price is much more expensive than the soft starter, and the structure is much more complex.