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China soft starters manufacturer
how a soft starter works?
Working principle
Conventionally the magnetic amplifiers have been equated with saturable core reactors, which work on the principle of superimposition of magnetic fluxes in the additive mode thereby saturating the magnetic core & varying the impedance. These have found limited usage in alternating current circuits because they require D.C. excitation & generate a heavy percentage of harmonics in the current waveform due to core saturation.
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. Oppposing flux linkages are impressed on the same magnetic circuit, thus reducing total flux & hence reducing the impedance.
Total flux linkage = main flux linkage – opposition flux linkage
N I = N1*I1 – N2*I2
The system is designed to provide a predetermined constant current in the motor windings in the starting zone. The main flux is generated by the current in the motor winding and the opposing flux is generated by the counter emf of the motor as the motor speed increases. The net flux thus reduces, allowing the motor voltage to rise gradually form as low as 50% to 96% while keeping the current within the prefixed limit, thus efforting a smooth start. In fact the reduced start current allows closer calibration of the protective relays.
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.
Main features of Soft Starter
These are the main features and benefits of soft starter:
The soft starting sequence
A Soft starter normally operates in three distinct stages:
These operating stages are as shown in figure below:
Conventionally the magnetic amplifiers have been equated with saturable core reactors, which work on the principle of superimposition of magnetic fluxes in the additive mode thereby saturating the magnetic core & varying the impedance. These have found limited usage in alternating current circuits because they require D.C. excitation & generate a heavy percentage of harmonics in the current waveform due to core saturation.
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. Oppposing flux linkages are impressed on the same magnetic circuit, thus reducing total flux & hence reducing the impedance.
Total flux linkage = main flux linkage – opposition flux linkage
N I = N1*I1 – N2*I2
The system is designed to provide a predetermined constant current in the motor windings in the starting zone. The main flux is generated by the current in the motor winding and the opposing flux is generated by the counter emf of the motor as the motor speed increases. The net flux thus reduces, allowing the motor voltage to rise gradually form as low as 50% to 96% while keeping the current within the prefixed limit, thus efforting a smooth start. In fact the reduced start current allows closer calibration of the protective relays.
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.
Main features of Soft Starter
These are the main features and benefits of soft starter:
- Fastest payback period
- Avoids fluid hammer
- Easy to install
- In built protection
- Designed for extreme operating conditions
- Programmable current and torque limits
- Programmable acceleration and deceleration ramps
- Two set point current limits
- Instantaneous protections
The soft starting sequence
A Soft starter normally operates in three distinct stages:
- Ramp
- Dwell period
- Energy Optimizing
These operating stages are as shown in figure below:
900 kw motor is tripping in unbalance current even though the motor winding resistance is balance.motor is drawing unbalance current.
how too design softstarters ( reactor chokes ) for 20 to 100 HP motors ,,,
We are designing chokes and reactors ( input and output chokes for VFD) using RALE software .. Pls suggest .
How to consider current , ramp up time and and delay /....
We are designing chokes and reactors ( input and output chokes for VFD) using RALE software .. Pls suggest .
How to consider current , ramp up time and and delay /....
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