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Problem in parallel operation of Booksize Braking Module:

Created by: Bist at: 1/17/2011 6:41 AM (9 Replies)

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1/17/2011 6:41 AM	Rate (0)
Bist Posts: 27 Rating: (1)	Hello, We have a BLM 6SL3130-1TE31-0AA0; 100KW rectifier (no regenerative feedback capability) to power a common dc link.We have connected 3 Braking modules 6SL3100-1AE31-0AA0 and 1 Braking resistor 6SL3100-1BE31-0AA0 for each BM in parallel to limit the dc link voltage during temporary regenerative operation.As mentioned in the manual the Braking resistor switches ON when the dc link voltage reaches 770 V.I am facing a problem that during the dc link discharge operation only 1 Braking resistor switches ON (i.e. chopper gets activated) while the other two does not switches ON. So after some time the Braking Module goes into I2t shutdown and the second Braking resistor switches ON. We want that all three Braking resistors should switch ON during dc link discharge to equally discharge energy in 3 Braking resistors. So any one can please explain the reason for the same Regards Bist
Bist Posts: 27 Rating: (1)
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1/17/2011 2:50 PM	Rate (0)
jacek d Platinum Member Joined: 9/23/2005 Last visit: 10/11/2024 Posts: 4750 Rating: (726)	This may help you. Generally, when operating braking modules in parallel, they need kind of coordination. Otherwise. because of the way things used to be, one of them, the one with lowest switch-on limit (not the setting mentioned in manual, but the real one) fires first and all the others never.
	Regards, Jacek What is confusing you is the fact that you never see a number but always its digit representation. So you end up thinking that the number is the representation. - Andrej Bauer Any claims against me - based on whatever legal reason - resulting from the use of any code and/or ideas presented on this forum shall be excluded. #StayWithUkraine
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1/17/2011 6:06 PM	Rate (0)
Bist Posts: 27 Rating: (1)	jacek d This may help you. Generally, when operating braking modules in parallel, they need kind of coordination. Otherwise. because of the way things used to be, one of them, the one with lowest switch-on limit (not the setting mentioned in manual, but the real one) fires first and all the others never. Sir, I did not get your "they need kind of coordination" phrase. How can we provide that coordination?
Bist Posts: 27 Rating: (1)
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1/18/2011 7:11 AM	Rate (0)
Technology Team Platinum Expert Joined: 10/11/2006 Last visit: 10/11/2024 Posts: 5911 Rating: (809)	Hello Bist, unfortunately, the paralleling of this booksize units is only useful for increasing the available maximum braking power, e.g. if the regenerative energy is higher 100 kW. This is due to the switch on limits as already described by jacek. There are other braking units working with variable PWM output depending on the actual voltage and these units can also be used parallel to increase the continuous braking power. The units for MASTERDRIVES and for SINAMICS Chassis are working with this system and also a booksize compact unit will be available soon.So for your problem, you can now only change to a Masterdrives braking unit or wait for the booksize compact units. There is no possibility for coordination between the actual booksize braking units.
	With best regards, Technology Team Application consulting and pre sales support for SINAMICS, SIMATIC Technology, SIMOTION, SIMOTICS and MOTION CONNECT
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1/18/2011 8:14 AM	Rate (0)
Bist Posts: 27 Rating: (1)	Sir, you mean that the existing braking modules cannot be connected in parallel??? It is mentioned in the manual that the booksize braking modules can be connected in parallel so why we have to worry about the co-ordination? Regards Bist
Bist Posts: 27 Rating: (1)
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1/18/2011 9:04 AM	Rate (0)
jacek d Platinum Member Joined: 9/23/2005 Last visit: 10/11/2024 Posts: 4750 Rating: (726)	It looks like that parallel connection can only be used for so-called fast discharge and not for preventing DC bus overvoltage. Or I'm missing something You should think of a line module with energyfeedback.
	Regards, Jacek What is confusing you is the fact that you never see a number but always its digit representation. So you end up thinking that the number is the representation. - Andrej Bauer Any claims against me - based on whatever legal reason - resulting from the use of any code and/or ideas presented on this forum shall be excluded. #StayWithUkraine
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1/18/2011 11:27 AM	Rate (0)
Bist Posts: 27 Rating: (1)	Hello jacek d, I think the use of Braking moduletofast discharge braking energyis to preventdrive tripping on overvoltage fault. Regards Bist
Bist Posts: 27 Rating: (1)
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1/18/2011 11:38 AM	Rate (0)
jacek d Platinum Member Joined: 9/23/2005 Last visit: 10/11/2024 Posts: 4750 Rating: (726)	I'm not sure. They write something about completly (to 0V) discharging of DCbus with disconected LM supply and disabled MMs. It seems not to be the same as preventing overvoltage of DC bus.
	Regards, Jacek What is confusing you is the fact that you never see a number but always its digit representation. So you end up thinking that the number is the representation. - Andrej Bauer Any claims against me - based on whatever legal reason - resulting from the use of any code and/or ideas presented on this forum shall be excluded. #StayWithUkraine
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1/18/2011 12:10 PM	Rate (0)
Technology Team Platinum Expert Joined: 10/11/2006 Last visit: 10/11/2024 Posts: 5911 Rating: (809)	Hello, paralleling can be used, if you need to increase the maximum power e.g. if you have between 100 kW and 200 kW you would need two units. In this casethe unit with the lowest switch on level would be switch on first, but due to the higher power (on the unit P=U²/R is discharged), the voltage would still (slower) increase and the second unit switches also on. If the regenerative power is lower than the maximum power of one unit, the unit with the lowest level would switch on and the voltage would decrease, so the level on other units would not be reached. Therefore paralleling for continuous power higher than the continuous power of a single unit is not useful. The fast discharge function is to discharge the dc link to 0V after the infeed is offand brings it so faster to a save level (otherwise 5 minutes).
	With best regards, Technology Team Application consulting and pre sales support for SINAMICS, SIMATIC Technology, SIMOTION, SIMOTICS and MOTION CONNECT
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5/6/2014 3:13 PM	Rate (0)
A.Johnsen Experienced Member Joined: 6/1/2006 Last visit: 10/4/2024 Posts: 19 Rating: (0)	Hi , We have three braking modulesconnected in parallell andhave the same sharing problem with nominal power. A possiblesolution for the parallel connection to distribute the load between the amount of braking modules canbe to enable/disable the braking modulesin a pattern. On forxx sec, off for xx sec.

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