How to Size SCR's for Motor Drive

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SquidSoup Participant Join Date: Jul 2010 Posts: 2	How to Size SCR's for Motor Drive 07/30/2010 3:40 AM
	I have two bad SCR's (Thyristors Dual Diode) in a motor drive. They are obsolete parts made in Federal Rep of Germany, (pre-wall) and I can't get the specific datasheet on them. P#MCC90-16I01 The specifics are; 480VAC, 3Ph in fused at 150A. Motor is 500VDC, 40HP, 67.2 Armature Amps, FLR Amps 1-4, Max Field Amps 4.0, Stack Size 126. Reversable. This Thyristor is made by IXYS. The only part number I can come close to in their selection guide is MCC95-16I01. Can anyone tell me if MCC90-16I01 and MCC95-16I01 are compatible or how to find out. I've had not response from Mfr. IXYS.
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	Pathfinder Tags: DC Drive SCR Thyristor Dual.

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Winfield Hill Power-User Join Date: May 2010 Location: Cambridge, MA Posts: 390 Good Answers: 82	#1 Re: How to Size SCR's for Motor Drive 07/30/2010 9:39 AM
	One small point, the correct ABB p/n is MCC90-16IO1, that's an IO rather than a I0. The MCC90 means the part is rated at I_TAVM = 96A at 85C (the lowest rating in the series, other parts have 130, 160, 220, etc ratings), and the -16 means it's rated at V_RM = 1.6kV (the highest voltage rating in the series). The IXYS MCC95-16IO1B has a slightly-higher current rating, I_TAVM = 112A, which should be even better for your application. It appears they've made improvements in the process, and have upgraded the part number to reflect that. The newer series also offers higher-voltage 1.8kV parts, but distributors don't seem to be carrying it. BTW, I found two eBay items for MCC90-16IO1 thyristors, at about $17 each. Although they're used, the seller offers a three-month warranty. It's a little better than DigiKey's $64 price for a MCC95-16IO1B. Also, if you want the exact p/n, you could argue. __________________ Thanks, Win
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Delmar Power-User Join Date: Sep 2006 Location: Houston Texas Posts: 282 Good Answers: 16	#2 Re: How to Size SCR's for Motor Drive 07/31/2010 12:11 AM
	If you want to minimize future downtime due to obsolete drive failures you could consider replacing with a modern unit. Attached is a link for an Allen-Bradley PowerFlex DC http://www.ab.com/en/epub/catalogs/36265/1323285/9560203/ __________________ Specializing in Dynamic Weighing Systems for Powder and Bulk Solids Handling
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SquidSoup Participant Join Date: Jul 2010 Posts: 2	#3 Re: How to Size SCR's for Motor Drive 07/31/2010 1:22 AM
	Thanks for the timely responses, Winfield and Delmar! I appreciate your expertise Winfield and have given my mgt. the link to your response. I don't think they are ready to replace the drive Delmar. We have suggested it many times. Maybe next quarter! AB/Rockwell is my specialty also. I am knew to Global Spec. I knew I would like this resource! :)
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Shepster Member Join Date: Apr 2010 Posts: 9	#4 Re: How to Size SCR's for Motor Drive 07/31/2010 10:17 AM
	Have you actually seen the SCRs? Since being pre-wall, I seriously doubt that these scrs are anything but discrete components i.e. a metal can with a threaded stud and two connections protruding from the opposite end, for example. Whatever the configuration, it is likely you can find an scr of later construction that will fit in the board/heatsink. Data sheets for new(er) SCRs abound so wouldn't it simply be a matter of matching the replacement scrs' parameters with the motor requirements? Parameter values such as gate current/voltage can be taken from the circuit readily I would think. Being an AB person, and per Delmar's suggestion, I'm sure you have extolled the virtues of drive replacement to the management, yes? Price/size/features of new units, while not only solving your current crisis, can make an old machine perform much better...with adjustable acceleration curves, tighter regulation, more safety features, etc. The improvement in performance can often make the ROI on the new drive quite short. Good luck __________________ Shepster
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Winfield Hill Power-User Join Date: May 2010 Location: Cambridge, MA Posts: 390 Good Answers: 82	#5 In reply to #4 Re: How to Size SCR's for Motor Drive 07/31/2010 2:34 PM
	I posted a photo of the SCR module above. The ABB components were quite advanced, actually, as far as module assemblies go, with floating captive-nut bolts for power connections and tabs for control connections and an isolated thick metal bolt-down heat-sink baseplate. Probably not as attractive as a modern IGBT PWM power controller, but an SCR phase-control motor-winding power controller needn't be a complete slouch, given that the ac-cycle phase-control timing is short compared to the motor & load inertia. __________________ Thanks, Win
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grassridge Active Contributor Join Date: Jul 2010 Posts: 23	#6 Re: How to Size SCR's for Motor Drive 08/01/2010 1:33 PM
	Contact Semikron .com Pat __________________ grassridge
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