A soft starter is a solid-state device that protects AC electric motors from damage caused by sudden influxes of power by limiting the large initial inrush of current associated with motor startup . They provide a gentle ramp up to full speed and are used only at startup (and stop, if equipped).
What is the advantage of soft starter?
A soft starter ensures smooth and uniform starting by torque control for gradual acceleration of the drive system which goes on to help in preventing jerks (in the case of phase 3 control starters). This extends the life of mechanical components and reduces their maintenance requirements.
How does a soft start work?
Essentially, a soft starter works by controlling the amount of voltage running through the motors circuits . It does this by limiting torque in the motor. This in turn allows the soft starter to reduce the voltage and allows it to gradually stop reducing the voltage to allow for a smooth progression of current.
Where is soft starter used?
Soft Starters for motors are commonly used in industrial applications that have a high inertia load that requires a large inrush of current. Soft starters are commonly used in industrial applications that have a high inertia load that requires a large inrush of current.
What is soft starter in electrical?
A Soft Starter is a device that starts motors with reduced power supplied at start-up . Reducing the power reduces potentially damaging electrical and mechanical shocks on the system. As the name implies, starters “start” motors. They can also stop, reverse, accelerate and protect them.
What is the difference between a soft start and a VFD?
The main difference between the two is that a VFD can vary the speed of a motor while a soft starter only controls the starting and stopping of that motor. ... A VFD is the better choice if speed control is required.
Do soft starters save energy?
Soft starters are limited in the amount of money and energy they can save , primarily due to the fact they only influence the start-up and stopping processes of machinery. That said, some high-end soft starters can achieve up to 99 percent better energy efficiency, compared to normal start-up periods.
How much does a soft starter reduce starting current?
For this motor, the initial current when it is started is 600 percent, or six times the motor’s full load current rating . The soft starter can be set to reduce this current, for example, in this case, to 300% . This limits the inrush current on the utility line .
- Steel industries (Rolling mills and processing lines)
- Cement industries.
- Sugar plants.
- Paper and pulp.
- Rubber and plastic.
- Textile industries.
- Machine tool applications.
- Power sector.
Does soft starter reduce starting current?
A soft starter can eliminate these problems by gradually increasing voltage to the motor terminals during startup, providing a controlled ramp-up to full speed. This lowers inrush current and controls starting torque, reducing mechanical shocks to the system and to the product.
Is a soft starter a drive?
Soft starters are often the more economical choice for applications that require speed and torque control only during motor startup . ... A variable frequency drive (VFD) is a motor control device that protects and controls the speed of an AC induction motor.
How do I choose a soft starter motor?
Soft starter sizing is determined by the horsepower or kW rating of the motor , coupled with the mains operating voltage. In an established installation that uses a NEMA-rated starter, a replacement soft starter may be selected based on the NEMA size of the starter.
How do you test a soft starter?
Tests. Disconnect the supply and the motor from the soft starter, Measure the resistance of the SCRs using a 500V insulation tester such as a megger . This can be done with the electronics connected, no damage will be caused by the 500V tester.
What are the types of starter?
- Manual Starter.
- Magnetic Starter.
- Direct Online (DOL) Starter.
- Stator Resistance starter.
- Rotor Resistance or Slip Ring Motor Starter.
- Autotransformer Starter.
- Star Delta Starter.
- Soft Starter.
How do you make a soft starter?
One approach to a soft start circuit is to limit the inrush current by adding a power resistor in series with the transformer primary . A schematic of such a resistor-based soft start circuit is shown below. The resistor is usually a parallel combination of power resistors, and relays are often used for the switches.
How many types of starter are there?
Four particular varieties of motor starters are: Across-The-Line, the Reversing Starter, the Multispeed Starter, and the Reduced Voltage Starter. Across-the-line or Full Voltage Non-Reversing (FVNR) is the most commonly used general purpose starter. This starter connects the incoming power directly to the motor.
