What is Soft Starter? Its Working, Diagram and Applications
The soft starter is a type of motor starter that uses the voltage reduction technique to reduce the voltage during the starting of the motor. The soft starter offers a gradual increase in the voltage during the motor startup. This will allow the motor to slowly accelerate & gain speed in a smooth fashion. May 06, · A soft starter will be located inside the control panel and will be supplied with three phase power on the top. Then on the bottom, it will supply three phase power out to the motor. Soft Starter Control Methods The soft starter can be controlled either by a direct start/stop wiring or, it can be controlled over Ethernet.
Soft starters can be used to eliminate belt squeal, protect against water hammer, reduce voltage drop during motor starting, prolong equipment life, or reduce the size of a standby generator. They provide smooth controlled starting and stopping of mechanical equipment by reducing the torque of the motor, hence reducing stress on the motor and extending the lifespan of the system.
It is not going to be a smooth start. The stress caused by the sudden change in torque will wear on the motor and driven equipment as well as stressing the power supply. This can cause failures of bearings, couplings, pulleys, belts, etc. Now imagine how this would affect equipment that needs to start and stop frequently.
At VFDs. Here are some of its features:. Common soft starter applications include: blowers, compressors, conveyors, chippers, fans, exhausters, pumps, rock crushers. Yin is a content producer at VFDs. With over a decade of graphic design, product photography, and business background, he helps creating visual designs, blog content, and educational videos.
Move Items to Quote. Skip to Content Have questions? Call us at Compare Products. Variable Frequency Drives. Electric Motors. Medium Voltage VFDs. Medium Voltage Motors. Power Quality Products. VFD Panels. Industrial Controls. Mitisubishi Electric. US Motors - Nidec. What is a Variable Frequency Drive? VFD Buying Guide. VFD Panel. How to Read a Motor Nameplate. VFD How to Videos. How to Wire a VFD. Some advantages of soft starters are: About one quarter to one third the cost of a comparable VFD No harmonics to worry about Start and stop softly to reduce stress on the motor and connected equipment Reduce voltage drops and associated electrical problems However, there is no control for motor speed.
When do you need a soft starter? Admin Yin is a content producer at VFDs. Complete the form at the bottom of the page, how to make a bootable usb disk call us at to get your technical questions answered.
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Apr 19, · Soft start panels are beneficial because they increase the longevity of the motor by reducing the stress it undergoes during start up. Soft start panels are designed to accelerate, decelerate, and protect three phase motors. They are easy to install and require no maintenance. Protecting the pump is vital to the operation and this is an easy. A soft starter, like its name, is a device that provides a “soft start” for the motor by gradually ramping up the voltage. Soft Starters are used to control torque and reduce starting current.
A motor soft starter is a device used with AC electrical motors to temporarily reduce the load and torque in the powertrain and electric current surge of the motor during start-up. This reduces the mechanical stress on the motor and shaft, as well as the electrodynamic stresses on the attached power cables and electrical distribution network , extending the lifespan of the system.
It can consist of mechanical or electrical devices, or a combination of both. Mechanical soft starters include clutches and several types of couplings using a fluid , magnetic forces, or steel shot to transmit torque, similar to other forms of torque limiter. Electrical soft starters can be any control system that reduces the torque by temporarily reducing the voltage or current input, or a device that temporarily alters how the motor is connected in the electric circuit.
Across-the line starting of induction motors is accompanied by inrush currents up to times higher than running current inrush current can reach levels of 10 times for higher efficiency motors , and starting torque up to 3 times higher than running torque. The increased torque results in sudden mechanical stress on the machine which leads to a reduced service life. Moreover, the high inrush current stresses the power supply, which may lead to voltage dips. As a result, lifespan of sensitive equipment may be reduced.
A soft starter continuously controls the three-phase motor's voltage supply during the start-up phase. This way, the motor is adjusted to the machine's load behavior. Mechanical operating equipment is accelerated smoothly. This lengthens service life, improves operating behavior, and smooths work flows. Electrical soft starters can use solid state devices to control the current flow and therefore the voltage applied to the motor.
Solid state soft starters can control one or more phases of the voltage applied to the induction motor with the best results achieved by three-phase control. Soft starters controlled via two phases have the disadvantage that the uncontrolled phase will always shows some current unbalance with respect to the controlled phases. Typically, the voltage is controlled by reverse- parallel -connected silicon-controlled rectifiers thyristors , but in some circumstances with three-phase control, the control elements can be a reverse-parallel-connected SCR and diode.
Another way to limit motor starting current is a series reactor. Using an air core series reactor soft starter is very common practice for applications like pump, compressor, fan etc. Usually high starting torque applications do not use this method. Soft starters can be set up to the requirements of the individual application. Compared to variable-frequency drives, soft starters require very few user adjustments.
Some soft starters also include a "learning" process to automatically adapt the drive settings to the characteristics of a motor load, to reduce the power inrush requirement at the start.
In pump applications, a soft starter can avoid pressure surges, also known as water hammering. Conveyor belt systems can be smoothly started, avoiding jerk and stress on drive components. Fans or other systems with belt drives can be started slowly to avoid belt slipping as well as air pressure surges. In all systems, a soft start limits the inrush current and so improves stability of the power supply and reduces transient voltage drops that may affect other loads.
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