Soft starter or VFD

VFD IS A BETTER CHOICE.THE SOFT STARTER WILL GIVE SOME STARTING KICK DUE TO SOME INITIAL VOLTAGE(SAY ABOUT 150%),BUT VFD WILL START FROM ZERO AND WILL NOT GIVE ANY STARTING KICK IF ACCELERATION TIME IS CAREFULLY CHOSEN DEPENDING UPON APPLICATION.THIS IS PARTICULARLY USEFUL WHEN A BIG MOTOR IS TO BE STARTED ON A DG SET.

sir can u tell me the other advantages of the VFD and the approx difference in price of VFD and soft starter.

<...the other advantages of the VFD....>

The more intelligent, more modern, VFD will have a range of user parameters that can optimise the use of the motor/drive combination. A correctly-set VFD will provide a measure of energy saving over other motor operating methods, which can in some cases justify its installation from the beginning.

<...the approx difference in price of VFD and soft starter...>

These things are best determined locally on the basis of the size of motor to be started, which is omitted from this posting, incidentally, as is the country of operation. A google will produce lists of VFD suppliers, and the rest is best tackled by telephone.

Starting current is dependent upon load connected to the motor. In general though, most soft starter applications will require at least 350% FLA to be successful; heavier loads or faster accelerations may require more. VFDs can theoretically accelerate a motor with 100% FLA as long as acceleration time is irrelevant. But again, if fast acceleration is necessary you may have to go to 150% or maybe even 200% (which may require oversizing the VFD if for more than a few seconds).

In general, the price delta of VFDs is between 5x and 10x that of an equivalent soft starter. At the size you need, closer to 10x.

I standby JReaf, its max 350% for Soft starter. The selection will go by the upstream supply capacity and price. If the variable speed is not required during running of motor then I will suggest to go by softstarter. Recently I was in a similar situation of selecting starter of a 3.5MW compressor motor, I found the soft starter is the most economic.

Chosing the right starter has a lot to do with the application of the motor and many other perimeters. I always leave to the experts in the field to answer that question. I'm not sure where you are located but here are some very good referrals for you:

Robert Hansen, ABB Drives, Cell 206-979-0586, office 800-333-3103, email rhansen@carmodycompany.com Robert is an expert regarding VFD's & Soft Starters.

Fernando Neal, ABB Low Voltage Products & Systems Manager, Cell 206-465-8378, office 888-385-1221, email fernando.neal@us.abb.com Fernando is very knowledgable about Soft Starters vs VFD's.

These referrals are located in the Pacific NW Region of the US. You can go to ABB Drives on your search engine and find ABB Rep's throughout the World who can help you with your solution.

Have a Wonderful Day!

MrHandyMan

Thanks to all for your valuable suggestions

there are programable softstarts for ramp ups , and vfd that has all kinds of parameters I just installed a mitsubshi with 1500 parameters and best of all a 3 year warrenty, good luck,have fun!! james m kieffer west fargo nd

VFD is the best option...it reduces the DG rating required.

Initial cost would be high, typically 2-3 times ( varies with the manufacturer) the cost of softstarter, but it pays back if you have a variable speed application (variable load).

Good luck.

You should be able to use a hand crank to start it...

If there is no need for speed control , the best suitable for starting is soft starters , you have a choise of single phase controlled soft starter or three phased control soft starter , depending on your heavy duty application .

and

regarding power saving ,

In reality VFD would consume more power (if the application is only starting and stoping the motors ), as soft starter by pass the connection after ramp up as vfd continue to consume energy themselves even after ramping up , so do not be carried away by marketing fuss created by drive sellers as they are damn expensive too.

i would suggest this softstarters has they have been robust and gave no problems (and are made in Germany)

http://kimo.de/index.php?file=produkte/sanftluebersicht.html&menu=1&lang=EN