Soft Starter for HT Motors

Soft starters are available in the market even for HT drives.I had come across in one of my projects. Pl check the characterstics of the soft starter (the ramp characterstics) and the motor charatrestics before installing.Incoming cable shall be terminated in the soft starter panel.The motor terminals get supply from the softstarter panel.U will be able to adjust the time of acceleration to full speed. regards Ravipra01

There are only a few manufacturers of medium voltage soft starters for 6600V. Motortronics is one, and their product is brand-labeled to Siemens, ABB, GE, Schneider, Toshiba, Emotron, Elettronica Santerno, and Saftronics. Benshaw is another, they are also brand-labeled to Teco. Allen Bradley is another, they are not labeled by anyone else. Solcon is the last for sure, they are brand labeled by several other EU and Asian companies as well. Aucom and Eaton also advertise MV soft starters, but as far as I know neither have yet manufactured a 6600V version, and the SCRs for 6600V pose some unique challenges that you do not want to be the test case for. Of those, the Motortronics is the most robust, but if I were you I would consider buying it from one of their partners such as Siemens, Toshiba or ABB so that you can get better worldwide support (I am assuming you are not in the USA because we don't use 6600V). If you are in India, Elletronica Santerno has an excellent service organization there.

Your reason for doing this is flawed however. Using a solid state starter will not reduce the heat in the rotor. The amount of energy required to start a motor from a dead stop to full speed is always exactly the same (at a fixed frequency). If you lower the current you will increase the time, but the area under the curve remains constant In fact if you are already using an autotransformer type starter, when you switch to a solid state starter your line current will increase for the same amount of motor current. This may actually cause more problems for you because it may create more of a voltage drop on your system than the autotransformer starter did.

The only real method of reducing motor heat on startup will be by using a VFD, which will probably be prohibitively expensive if you have no other benefit from variable speed.

Thanks for your prompt reply. Yes as you said I'm not from USA neither India; but I'm from Malaysia. This requirement is for offshore platform in oil & gas industry. If the concern is reduce the starting current then which is the best starting method? Do you can recommend any reliable brand? Hope I can get best answer from you.

Dear Anbu Mani,

I have been conceptualising Ballastic Method of Softsarting of HV machines. This cocept will be able to reduce power lost during starting. However I have not yet made any experimental model due to cost. If any sponsorer come forward I will be happy to do the prototyping. I am located in india sawraye@sify.com.

Prof S A Waheed Raye

Dear Sir,

we are a producer of LV amd MV soft starters, we are intrested to hear what you have to say.

you can use benshaw soft starters they are robust and can take care of your problem. Actually I am marketing them in middle east and they are real good?

First you need to prioritize your needs and concerns. First you said motor heating, now you mention starting current reduction.

If your primary concern is reducing starting current to avoid voltage drop on a weak system, the AutoTransformer that you have now is the best solution without spending a lot of money. The problem with AT starting is that the transformers have a limited thermal capacity and there are only 2 or 3 steps of voltage reduction to choose from. So if you are at the 65% taps now, your only lower choice is 50%, which may not give you enough torque to start before the thermal protection devices in the autotransformer coil drops out the starter. Have you tried doing that yet? If you are already at the 50% taps (as I suspect you might be because you said the starting current was 300%), then this may be as good as it can get.

At the 50% taps, if your motor current is 300% of FLA, then the current drawn from the line is 150% of FLA. If you change to a soft starter, ANY BRAND of soft starter, and set the current for that same 300%, the current drawn from the line will be 300%, twice that of the autotransformer. The main advantage a soft starter has is that you can set the current limit to be below 300%. However, an AC motor will not accelerate to full speed without pulling at least 200% current at some point in the cycle, so even though some brands of soft starter advertise they can be adjusted lower, the motor will not start. So switching to a soft starter will not work at 150% of FLA, the level you now pull from the line with your AT starter. This is why I said that switching to a soft starter might actually cause more problems for you.

If your primary problem is that the motor is overheating during acceleration, then the only electrical solution that will prevent this will be a variable frequency drive, because it can allow the motor to develope full torque without exceeding rated current, so the motor thermal stress is no different than running.

One other possibility for keeping motor temperature down is a magnetic drive system. It allows the motor to start completely unloaded then ramps the load at any rate necessary to prevent stress by magnetically coupling it. This is a common solution for large motors with limited power sources.

I wonder what your issue is with motor overheating anyway. Is the motor tripping out on overload before it accelerates? How are you measuring heat and how are you defining "over"?

How about a pony motor to assist in starting?

call Mr. Gandhi

Emco Kimo

We are Emco Kimo in India.

We have sold and installed soft starters in India for ABB, Siemens, L&T, approx 8000 soft starters have been sold and installed successfully. Largest is for Oil and Gas platform in India for 8000kw at 11KV, and also for IP65 cabinets. We have the largest installed base with 200 soft starters alone installed for ONGC in India.

We are approved by all consultants in India, and supply to a wide industry base. We are dedicated to supply SOLCON, MV, LV, and HT soft starters and also offer MV Inverters, Drives, and complete MCC soltuions all over India.

You have no shame sir.

People like you who use forums as a means of free advertising will end up rendering them useless. If I wanted to see an ad, I would use a search engine. If I come to a forum for help and get advertisements instead, my time is wasted.

I feel compelled to AVOID your product whenever possible.

Mr. Mani,

Send me the load curves and motor curves, and motor data sheet.

We will calculate the starting time and lowest current and then make a quotation.

Send it to my e mail box, you already regsisteres on my e mail box.

Thanks,

C.Gandhi

Mr. Anbu Mani,

Please give me your contact details.

Please give all information for contact.

My application team will contact you and verify if it is technically possible to start this motor, the way you want it to.

I have a PHD in Motor control and Soft Starters.

Thanks,

C.Gandhi

HI

FOR UR APPLICATION I SUGGEST TO USE 2 STEPS IN STARTING

1ST STEPS IS 5.5KV FOR 8- 12SEC

2ND STEP IS 6.6KV RUNNING

WE HAVE USED THIS APPLICATION & IS RUNNING FROM 1999 UPTO DATE

IF U REQUIRE ANY MORE INOFRMATION ON INSTALLATION & RELAY PL CONTACT ME

LOL, you post to a 2 year old thread, and all you have to offer is to tell him to do things the way he is already doing it!