Scinamics DCM 2 Different Ramp Up Times

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Abdullahliaqat Participant Join Date: Aug 2019 Posts: 1	Scinamics DCM 2 Different Ramp Up Times 08/22/2019 6:44 AM
	We have total four Siemens SINAMICS DCM convertor rated 830Vac, 1577Amps connected in parallel to drive a 2500KW DC Motor for rolling mill. As per Application the motor runs at two speeds. When Idle, motor runs at slower speed for example 300RPM and just at the time of hot metal rolling its speed is increased quickly up to 400rpm, After rolling the speed again returns to 300RPM. The cycle continues in this pattern. The problem we are facing is that the RAMP UP TIME is set to minimum due to quick change of speed required during rolling from 300 to 400 RPM. This minimum RAMP UP TIME effects the starting current when motor is started from stand still, it draws very large current due to this small ramp up time. Does Sinamics DCM convertor has the option to set two different ramp up times. One for starting and one for changing speed during running.
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PWSlack Guru Join Date: Jan 2007 Location: In the bothy, 7 chains down the line from Dodman's Lane level crossing, in the nation formerly known as Great Britain. Kettle's on. Posts: 32175 Good Answers: 839	#1 Re: Scinamics dcm 2 different ramp up times 08/22/2019 7:21 AM
	The thing to which the motor is attached has a great influence on the motor current. A call for fast acceleration will cause the current to rise in proportion to the call during the acceleration period. The possible outcomes to this activity are: Hit current limit within the <...convertor...> without tripping the overload, thereby limiting the acceleration to a lower value; Pass current limit within the <...convertor...> and trip the overload in an attempt to achieve desired acceleration; Reduce the rotational inertia so as to achieve acceleration without tripping the overload or hitting the current limit. That's it. __________________ "Did you get my e-mail?" - "The biggest problem in communication is the illusion that it has taken place" - George Bernard Shaw, 1856
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SolarEagle Guru Join Date: Mar 2007 Location: by the beach in Florida Posts: 33392 Good Answers: 1817	#2 Re: Scinamics dcm 2 different ramp up times 08/22/2019 8:20 AM
	Probably in here someplace... https://cache.industry.siemens.com/dl/files/889/55623889/att_106357/v1/dcm-converter-en.pdf __________________ All living things seek to control their own destiny....this is the purpose of life
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67model Guru Join Date: Dec 2010 Posts: 1686 Good Answers: 116	#5 In reply to #2 Re: Scinamics dcm 2 different ramp up times 08/23/2019 7:36 AM
	It seems to me that page 404 of section 10.9 of the mighty manual is saying [below Ramp-function integrator heading] that you can have one ramp setting after first ON until a speed & then swap to a second ramp setting. An email to Siemens may get a step by step setting modification instruction if the requirement is explained to them.
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PWSlack Guru Join Date: Jan 2007 Location: In the bothy, 7 chains down the line from Dodman's Lane level crossing, in the nation formerly known as Great Britain. Kettle's on. Posts: 32175 Good Answers: 839	#3 Re: Scinamics DCM 2 Different Ramp Up Times 08/22/2019 10:51 AM
	What did the local Siemens Technical Helpline have to say during the telephone calls made to it on this particular topic? __________________ "Did you get my e-mail?" - "The biggest problem in communication is the illusion that it has taken place" - George Bernard Shaw, 1856
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Codemaster Guru Join Date: Jul 2005 Location: Stoke-on-Trent, UK Posts: 4496 Good Answers: 137	#4 Re: Scinamics DCM 2 Different Ramp Up Times 08/22/2019 2:44 PM
	"Does Sinamics DCM convertor has the option to set two different ramp up times. One for starting and one for changing speed during running?" I don't know, but it seems odd if it doesn't, as one is going from 0 - 300rpm, the other from 300 - 400rpm. But as PWS says, Siemens will be able to tell you. __________________ Give masochists a fair crack of the whip
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