Skip to Content

Register Login

Industry Online Support

Technical Forum

Navigation

soft starter and vfd

Created by: Chetan2490 at: 5/26/2014 12:12 PM (20 Replies)

Rating (1)

Thanks 2

Result pages:: |; 1 | 2 | 3; |

21 Entries

Entries per page: 10 | 20 | all

5/27/2014 8:22 AM	Rate (0)
Ayman Elotaify Platinum Member Joined: 5/28/2008 Last visit: 11/6/2024 Posts: 4516 Rating: (839)	jeet2907 Ayman Elotaify @nkur Chetan2490 Dear experts, How soft starter is differ from VFD? Explain in Brief. Hi all I would like to add a question to it in which cases i need a softstarter??? Hello, Drive is a device to control speed of a motor. While Softstarter is a starting device. We use it to ensure that the motor start working smoothly and then motor work at fixed speed as if it is connected as a DOL. Softstarter is a replacement of Star-Delta starter. In many cases, it's better to use softstarter to ensure smooth start. We can see it in pumps for instance to avoid water hummering. Hope this helps. Dear Ayman Elotaify As you said that, Drive is a device to control speed of a motor. So want to know that DRIVE is used just for the speed control only??.....what is the main advantage of DRIVE over SOFT STARTER?? Hello, They are totally different. Softstarter is a starting device and you can not control speed from it Drive is speed control device. Hope this helps.
	Ayman Elotaify
Suggestion To thank
This contribution was helpful to 1 thankful Users SolutionFinder

5/27/2014 1:48 PM
kriipc Silver Member Joined: 4/11/2011 Last visit: 10/7/2024 Posts: 132 Rating: (7)	Ayman Elotaify Drive is speed control device. Hope this helps. Also it may work as torque control device.
	I'm just a human. Mistakes are allowed. Sorry for my english. Only 3 months of training and manuals :)
Suggestion

5/27/2014 4:49 PM
metwally mustafa Silver Member Joined: 10/10/2010 Last visit: 10/25/2024 Posts: 307 Rating: (15)	VFD has diffirent types of control modes to control torque and speed -V/F control (linear- parabolic- user define) -vector control with sensor(feedback encoder) -vector control sensorless all control modes are working in open loop ( V/F) or in closed loop ( closed loop vector )
	Last edited by: metwally mustafa at: 5/27/2014 4:50 PM
Suggestion

5/28/2014 7:04 AM
Chetan2490 Advanced Member Joined: 5/12/2014 Last visit: 9/9/2020 Posts: 149 Rating: (16)	metwally mustafa VFD has diffirent types of control modes to control torque and speed -V/F control (linear- parabolic- user define) -vector control with sensor(feedback encoder) -vector control sensorless all control modes are working in open loop ( V/F) or in closed loop ( closed loop vector ) Dear , Can you explain in detail about vector control??

Suggestion

5/28/2014 7:19 AM	Rate (0)
UMENCHO Diamond Member Joined: 3/21/2006 Last visit: 11/1/2024 Posts: 10229 Rating: (1181)	Knowledge BanksDrives

Suggestion To thank

5/28/2014 7:39 AM
Ayman Elotaify Platinum Member Joined: 5/28/2008 Last visit: 11/6/2024 Posts: 4516 Rating: (839)	Chetan2490 Dear , Can you explain in detail about vector control?? Please read this Tip: (Theory of inverter from scratch) new episode !
	Ayman Elotaify
Suggestion

5/28/2014 8:25 AM
ashishmistry390 Posts: 21 Rating: (0)	Chetan2490 Dear experts, How soft starter is differ from VFD? Explain in Brief. Dear Chetan2490 The primary purpose of a variable frequency drive (VFD) is to control the speed of an AC motor. It works by electronically changing the frequency of the power supplied to the motor. The applied voltage is also changed so that the ratio of voltage to frequency (V/Hz) is approximately constant. Since the operating speed of an AC motor is mostly determined by the frequency of the applied power, adjusting the frequency is the best means of adjusting the speed. A VFD also provides "soft" starting. When the motor is started, a very low frequency is applied. and the motor starts and runs without drawing a high current. If the voltage is properly controlled, the motor can produce up to 150% of rated torque while drawing proportional current. To accelerate the motor, the frequency is gradually increased so that the required torque is provided while accelerating with limited current. A soft starter electronically reduces the voltage applied to the motor during starting. That limits the starting current, but also limits the starting torque. Since AC motors can produce considerably more torque than their rated continuous running torque, starting with limited torque is usually acceptable. Once the motor reaches full speed, the voltage is increased to the normal running voltage for efficient operation. Regards, Ashish Mistry
ashishmistry390 Posts: 21 Rating: (0)
Suggestion

5/28/2014 11:00 AM
N. Vijay Silver Member Joined: 3/17/2013 Last visit: 8/25/2024 Posts: 481 Rating: (43)	HI You should use softstarter in applications where normal running load on the motor is variable like pulpers, compressors etc where there is no need to apply full voltage across the motor windings all the time while it is running. If mechanical load is reduced on motor voltage across windings also reduced, so that it will reduce the stress on motor winding. As mentioned by experts, it uses antiparallel SCR bridge to have controlled voltage. VFD regulatesboth Voltage and frequency there by speed is controlled Regards, Vijay

Suggestion

5/28/2014 12:12 PM
jeet2907 Posts: 235 Rating: (52)	Chetan2490 Dear experts, How soft starter is differ from VFD? Explain in Brief. Dear, Here is the main advantage of VFD over SS pls follow link Benefits
jeet2907 Posts: 235 Rating: (52)
Suggestion

5/28/2014 3:23 PM	Rate (0)
MHasan Posts: 63 Rating: (4)	Chetan2490 Dear experts, How soft starter is differ from VFD? Explain in Brief. Its very simple: VFD is usedfor motor: control speed/ switching in fwd-rev direction/ power saving in some application/ motor protection from overload, overheat etc. VFD also have acceleration/ de-acelleration (ramp-up/ ramp-down) options for protection of motor and mechanical connected structure. Whereas softstarters are mostly used for accelleation (ramp-up) functions.
MHasan Posts: 63 Rating: (4)
Suggestion To thank

|

Share this page:

Share this page on...

Follow us on