Soft Starters

Hi Guys,

I,m looking for some general info. on Soft Starters. Some info on identifing different types of soft starters as well as their operating principles, maybe a few drawings. as well as maybe some typical trubleshooting proceedures. There is a lot of info of this kind on VSD's on the web but little on soft starters. Have any of you guys found any info like this for soft starters?

I think if you go to the Eaton / Cutler HAmmer site they have catalog stuff on their IT S801 series RVSS (Reduced Voltage Solid State Starters). I've used them successfully. http://www.eatonelectrical.com/NASApp/cs/ContentServer?pagename=C-H/Common/AssetTemplateLink&c=Apubarticles&cid=985967803408&Sec=products

Allen Bradley also has some new products in this line. I haven't used them, but htey look lots better than the old SMC line. http://www.ab.com/industrialcontrols/products/solid-state_motor_control/soft_starters/smc-flex.html

Try doing a Google search on Reduced Voltage Starters (I got 96,000 results). Square D and Cutler Hammer both had technical papers on all types of reduced voltage starters not just [solid state]soft starts.

Also look for reduced voltage starting types:
Autotransformer
Part Winding
Wye-Delta
Primary Reactor/Resistance
Solid State Reduced Voltage

Got to seek to find!

sirhiss2 said:

Hi Guys,
I,m looking for some general info. on Soft Starters. Some info on identifing different types of soft starters as well as their operating principles, maybe a few drawings. as well as maybe some typical trubleshooting proceedures. There is a lot of info of this kind on VSD's on the web but little on soft starters. Have any of you guys found any info like this for soft starters?

Click to expand...

Look what Google turned up as the first item when I asked it to search for "soft starters". http://www.lmphotonics.com/sstart.htm I am always amazed at what is on the big WWW.

Tom Jenkins said:

I think if you go to the Eaton / Cutler HAmmer site they have catalog stuff on their IT S801 series RVSS (Reduced Voltage Solid State Starters). I've used them successfully. http://www.eatonelectrical.com/NASApp/cs/ContentServer?pagename=C-H/Common/AssetTemplateLink&c=Apubarticles&cid=985967803408&Sec=products

Allen Bradley also has some new products in this line. I haven't used them, but htey look lots better than the old SMC line. http://www.ab.com/industrialcontrols/products/solid-state_motor_control/soft_starters/smc-flex.html

Click to expand...

Tom, I have used the SMC-flex starters and I love them. I also like the SMC-3 starters. One thing I like about both starters is that they incorporate integrated bypass contactors, allowing use of a smaller frame. The SMC-FLex is feature loaded and C-NET, D-NET, E-NET compatible, so you have lots of performance data available. Almost everything I have done in the last couple of years has been softstarters, the SMC-3 is price/feature competivie with a conventional NEMA starter (the SMC-Flex is a bit more $$$$).

I've also used the C-H starters in the past as well with great success.

Thanks guys, I yahoo'ed it. I should have google'd it. Alot better response. With yahoo all I got were sales pitches. Thankyou randylud. That looks like a good site. To the guys who use soft starters quite often, in your experence, what are some of the most common problems you guys encounter with them? Most of my experience is with VSD's , AB 1336 Plus drives, Lens drive (Euro), and siemens 32's and master drives. Not too many soft starts. I'd like to here some "old War Stories" about problems with soft starts.

My most often seen problems:

Incorrect phase sequence on incoming power

Incorrect adjustment of FLA and starting current/time limits causing nuiscance trips

24 VDC power supply not having enough inrush capability for starting requirements (Cutler Hammer only)

Starters fail by SCRs shorting through, so motor won't stop unless breaker is opened (Older Square D only)

Some soft starters don`t actually look at the current while starting. They only limit voltage. Danfoss and probabally others actualy monitor the current so they know what it is doing. This way you really have more control on limiting the current the motor is pulling and also controlling starting torque.

Acceleration time - most solid state are 30sec max, some mechanical are longer

Line voltage imbalance tolerance range - some solid state have a hard time on closely sized generators

Starting torque - often times solid state units require a "voltage boost" setting when set to minimum starting current

Interesting thread. I was looking at the SMC-flex for soft start soft stop application. The problem I have is that all SEW motors in conveyer are equipped with brakes 330 V Ac coil hooked up directly on motor junction box.

So I dont know when brake will kick in. Anybody had any experience with a similar setup.

ty

Power the brake separately and use a contactor that is ON when softstart/drive has a STOP or no run command....in most cases this means using the stop or run command to power the contactor on to energize the brake to release it. You will have to determine the necessary configuration.

Make sure you have disabled any soft-stop feature (motor must be freewheeling) before energizing the brake.

Most of the problems I have seen with soft starters is the dirt accumulation and connections getting loose over the years.

Tom pretty much covered the other problems. Too many times people want the speed instant and that is not mechanically possible. Usually I set the accel ramps so the motor ramps up within normal limits. If you use the current limit to ramp on up, you may as well used an across the line start.

If you are using small HP motors, sometimes a VFD can be a better choice.

www.motortronics.com is another brand to check out.

The options available on most softstart packages are quite plentiful.

Interesting thread. Right now I am in the middle of upgrading a major city water supply pump station. 10 pumps at 250kW each, in a complex arrangement of manifolds and valving. The plant of course has to stay in operation as we stage the upgrade. What makes it really interesting is that the plant can be used 6 major different modes, and some pumps can be used in both parallel and series mode according to the flow regime required.

I've used CLX, dual redundant CNet and SMC-Flex with the new External IO option card that gives me 6In/2Out right in the motor cell to pick up things like isolators, contactors and a couple of external Thermistor Overtemp relays.

Some of the motors have two separate windings (6/8 pole) and we write the required FLA rating into the SMC before each start. Plus of course we pull back all the monitoring data we like. The SMC-Flex's have performed flawlessly.

Drive Executive makes setting up the SMC's an absolute doddle. Being able to sit in the office and drill through Ethernet, through the backplane, out onto the CNet and browse to the SMC you want to monitor has impressed the client no end.

I use a lot of soft starters and alsao soft stop. Nothing fancy like Philip though.

Most of mine are up to about 45 kW and I like the Sprechur & Schuh units. AB own them and probably have the same units. Set them up by DIPO switch and they work very well. Only thing I will not compromise is I always use the input filter modules.

They have thermal and othe protection built in. You just select what you want. Inbuilt fault output for your PLC and inbuilt instantaneous contact to drive your isolation contactor. Just tell the thing to go and it does.