VFD and Soft Starter Difference
Many people say about VFD and soft starters, that by using VFD, we start the motor smoothly and the same thing is said for Soft Starter as well. So now the question in our mind is that VFD and soft starter are the same?
But it is not like that at all. There is a lot of difference between VFD and soft starter. For this reason, you must have also seen that the cost of VFD is much higher than the soft starter. So in today's post, we will know the difference between this VFD and Soft Starter.
What is VFD and Soft Starter?
The main function of both of them is to keep the motor under control while starting and closing it slowly. Meaning it prevents the motor from starting and stopping all of a sudden. By doing this, there is no jerk in our mechanical system. But by using VFD, we get many more benefits.
And seeing these benefits, nowadays only VFD is being used in our place. But it is not that the soft starter has stopped or it will stop going forward. The soft starter is also very important in the electrical system.
You will easily understand the need for VFD and Soft Starter in the electrical system and the difference between VFD and Soft Starter. First of all, let's talk about VFD.
Also read about- What is Variable Frequency Drive use and its Working?
How does VFD work?
There are 3 main components in VFD.
1) Rectifier
2) Filter
3) Inverter
Rectifier- The basic function of the rectifier circuit is, it converts AC voltage into DC voltage. Once the AC voltage is converted into DC voltage, then the filter unit works. This filter unit filters that DC voltage, which is made from the rectifier.
Filter Unit- The DC voltage in the filter unit has come after filtering from the rectifier circuit. It is checked, whether the DC voltage has some properties of the AC voltage. The DC voltage in the filter unit becomes pure DC voltage after being filtered.
Inverter Unit- Once the DC voltage is filtered through the filter unit, then the job of the inverter unit is to convert that DC voltage back to AC voltage.
But now that we have got AC voltage from VFD, this AC Voltage will be in a rectified form, meaning we can change this AC voltage as we want the output. And the speed of the motor can be easily increased more or less than the AC voltage received from VFD.
How does a soft starter work?
If we talk about the main component of the soft starter, then there are 3 SCRs in the soft starter. These 3 SCRs are mounted in parallel inside the soft starter.
The basic function of a soft starter is that it gives a smooth start to the drive (motor) at starting. With the help of which we can eliminate the condition of a mechanical jerk.
If we talk about soft starter control, then the complete controlling of the soft starter is similar to VFD. But there is a rectifier, filter, and inverter unit for controlling the VFD.
Similarly, a microprocessor controller is placed inside the soft starter, which controls the entire process.
Difference between VFD and soft starter?
We use the soft starter to start the motor smoothly and to stop the motor smoothly.
VFD and Soft Starter
Talking about VFD on the same, VFD also provides a smooth start and smooth stop to the motor. Apart from this, VFD has other main functions, one of which is to control the motor.
In the case of a soft starter you cannot change the RPM of the motor only you can provide soft starting but in the case of VFD, you can also change the RPM of the motor as per your requirement.
So you get this advantage in VFD that whenever you want you can increase or decrease the speed of the motor with the help of VFD, but you cannot do this in the soft starter.
Smooth starting and smooth stopping of the motor, is called Acceleration and Deacceleration of the motor.
Also, one important thing is that soft starter does not produce harmonics. This is a great advantage of a soft starter. There is no case called harmonics in the soft starter, according to this, soft starter is considered very good.
Talking about VFDs, harmonics are created in our system by using them. And the third harmonics that are in them are produced a lot in VFDs.
Because of this, you must have seen inside many companies that they keep the extra filter along with VFD. This is a harmonic filter.
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