2MW Soft Start ?? 7

[Ian3142]

Dose anyone Know if there is such a thing as a 2MW soft start .. it's for starting a compressor ... I am also looking into a VSD as well ...

 

[Photocell]

Can u tell me what is the supply voltage available. As far as I know Soft start is suitable for low power motors.

 

[dpc]

Yes, they are available up to 60,000 hp and probably beyond.

Check this link for one supplier (there are others):

http://www.benshaw.com/index2.shtml

Try a Google search on Medium Voltage Solid State Starter

 

[Marke]

Hello Ian3142

Yes they are available, I have been involved in a couple at 440 volts, but in general, they would be at MV.
In addition to the links above, you could try

http://www.aucom.co.nz

Best regards,

Mark Empson

http://www.lmphotonics.com

 

[GGOSS]

Hello Ian3142,

There are a number of manufacturers of MV soft starters. In addition to the above you may want to try;

http://www.ab.com

http://www.solcon.co.il

There are a few more but their names/URL's escape me at the momment.

Regards,
GGOSS

 

[ScottyUK]

Two more to go at:

ABB

Siemens

Google picks 'em up alright.

-----------------------------------

Start each new day with a smile.

Get it over with.

 

[jbartos]

Suggestion: Alstom, Cegelec offer large soft starters and VSDs. Visit

http://www.alstom.com

http://www.cegelec.com/

etc. for more info

 

[jraef]

Just heard today on the news that the French Govt. is not going to bail Alstom out again. Likely that it will be carved up amongst the major players. You might want to avoid that alternative, at least for the time being. Turmoil like that usually translates into poor customer service for a while.

PS: jbartos,
I think you meant RFP. RFI would be Request for Information, a precursor to an RFP. Unless you meant Radio Frequency Interference, but I know not why you would!

"Venditori de oleum-vipera non vigere excordis populi"

 

[jraef]

By the way sed2developer, Cegelec Drives became Alstom Drives and Controls back in 1999 so you are right.

"Venditori de oleum-vipera non vigere excordis populi"

 

[jbartos]

Thanks jreaf for correction. One may send Request for Information (RFI) or Request for Proposal (RFP) or Request for Quotation (RFQ).

 

[purplepete]

I suggest for a motor that large, in addition to the good info available from the drive manufacturers (and vendors), you check thoroughly with the motor manufacturer on its suitability for such an application. There may be some serious tests to be done on the motor to ensure its winding insulation doesn't become a victim of high dV/dT, associated with solid state drives be they VSD or soft-start. Cheers

 

[Marke]

Hello PurplePete

I am interested in your comments re dv/dt problems with soft starters. Soft starters use SCRs which are very slow switching devices compared with IGBTs. I have not heard of any DV/DT problems with soft starters. Can you elaborate?

Best regards,

Mark Empson

http://www.lmphotonics.com

 

[pmbates]

Ian,

Soft start is probably your best alternative. A VSD, variable speed drive, or variable frequency drive, VFD, is much more expensive in th medium to high voltage. The advanage of the VFD is the ability to save energy on variable torque loads, fans and pumps typically. An energy savings come at a large price in the medium voltage arena. Voltage and FLA of the motor are the key to sizing this unit. I suggest contacting the following web site

http://www.benshaw.com

Patrick

 

[purplepete]

Marke, tahnks for your comments. My caution re the VSD and soft starter only comes from the switching on of the SCR part-way through a cycle (during the starting period of the starter). This produces only one steep-fronted rise per half cycle as distinct from the number produced by the kHz operation of the VSD IGBT's.
I agree with you this places a lot less stress on insulation systems but in a proposition such as the 2 MW machine (which I assume is not young) it should not be ignored. Some soft-starter manufacturers make reference to the dV/dt filters installed in their equipment.
My first VSD installation was to retro-fit an SCR-SCR type in the mid-seventies and within 18 hours precipitated a winding-to earth fault in a long-dormant insulation weakness in the rather older motor it supplied. I've had NO motor failures attributable to soft starters or VSD's since but only three of my direct projects have included soft starters in LV works. ... I've also been a lot more cautious.

 

[Marke]

Hello purplepete

Thanks for your reply.
The switching times with IGBTs are in the order of hundreds of nanoseconds, and as you suggest, these wavefronts are occuring at a very rapid rate, typically 5 - 15 KHz. I believe that the greatest problem is not from the switch ON, but from the switch OFF.
In the case of SCRs, the switch ON time can be in the order of microseconds to tens of microseconds, and the switch OFF more in the order of tens of microseconds to hundreds of microseconds. Switch OFF occurs when there is no curent flow, so there are no steep fronts at that point.
The switch ON is probably more gentle than a contactor closing, the only problem is that this occurs every half cycle during start.
I have not experienced any dv/dt failures that can be directly attributed to soft starters, and I have been involved with many tens of thousands of installations over more than twenty years. I would suggest that the potential for dv/dt damage is probably no worse than electromechanical switching.

Best regards,

Mark Empson

http://www.lmphotonics.com

 

[ksv]

i have come accross soft starters which work on an entirely differnt concept. It is called flux compensating type magnetic amplifier soft starters.These have references upto 10.5MW for compressor application.
There are two windings, main and the feedback winding on the same magnetic core.The soft starter offers a high impedence when the motor is startted.As the motor speed increases the emf to the feedback winding increases and the effective impedence decreases. The motor starts very smoothly.The soft starter is removed fron the circuit after the motor starts.
No harmonic problems!!!!
for more info please contact atr innotech@pn2.vsnl.net.in