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MM 420 and breaking resistor

Created by: hutdotedudotvn at: 5/2/2008 12:56 PM (5 Replies)

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5/2/2008 12:56 PM	Rate (0)
hutdotedudotvn Posts: 9 Rating: (0)	Hi all Now I have to use an MM420 to drive a motor which can operate in regenerative mode. So this leads to the increase in DC link voltage. But I'm wondering if it is possible to use a breaking resistor with a MM 420 ( I see a lot of documents but only for MM 440 ) If I don't use the resistor, is there any possibility of damaging the DC link capacitor Thanks for your help
hutdotedudotvn Posts: 9 Rating: (0)	Last edited by: hutdotedudotvn at: 5/2/2008 12:57 PM
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5/2/2008 1:17 PM	Rate (0)
Tambe Posts: 148 Rating: (11)	No there wont be any damage to capacitors in regenerating mode. There is a provision for a fault of over voltage F002 in the Micromaster. As the dc link voltage reaches to this trip level drive will cost down the motor immediately .(drive will trips with f002) . Once this condition achieves your dc link will go downs to normal value. And the capacitors will be protected. But in case the dc link voltage remains to the higher side for longer duration e(even motor is off) they will definitely damage the capacitors. Even frequent conditions like this will increase the energy dissipation in the cap and they will fail. For your specified operation you better go for MM440. which have some more features and you may use it in such a way that even breaking resistor will be eliminated.
Tambe Posts: 148 Rating: (11)
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5/2/2008 1:54 PM	Rate (0)
hutdotedudotvn Posts: 9 Rating: (0)	thanks tambe I see that in the DC outputs there are B+ and B- (attached image), does this mean that they are the ports to connect breaking resistor in MM 420 And by the way, what is the mean of the letter R+ (attached image ) plz help Attachment quest.JPG (382 Downloads)
hutdotedudotvn Posts: 9 Rating: (0)	Last edited by: hutdotedudotvn at: 5/2/2008 1:55 PM
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5/2/2008 1:59 PM	Rate (1)
diwa Silver Member Joined: 9/20/2006 Last visit: 3/5/2024 Posts: 307 Rating: (96)	Dear hutdotedudotvn , MM420 units do not have braking chopper in it, so you cannot connect a braking resistor to it. This feature is available in MM440 only. If you do not connect a braking resistor depending on the amount of regeneration your drive will frequently trip with DC link overvoltage fault. I am sure this will not be acceptable to you. So you need to go for a MM440. or second option is you connect abraking unit but this will be not be economical. diwa.

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5/2/2008 2:30 PM	Rate (0)
diwa Silver Member Joined: 9/20/2006 Last visit: 3/5/2024 Posts: 307 Rating: (96)	Dear hutdotedudotvn, The B+ and B- terminals are for connecting the braking resistor but it is onlyfor MM440. The cover of the drive is common for MM440 and MM420 hence you find the terminal in your drive. But if you see closely you will find the screws at these terminals are missing. Also the terminal R+ is the same as DC+. diwa.

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5/2/2008 3:14 PM	Rate (0)
Matise87 Posts: 3 Rating: (0)	The use of a breaking resistor with MM420 is not possible. You can use it only with MM440. With MM420, some solutions to solve the problem are: Supply voltage (p0210) must lie within limits indicated on rating plate. Vdc controller must be enabled (p1240) and parameterized properly. Ramp-down time (p1121) must match inertia of load. Required braking power must lie within specified limits. According to the MM420 Parameter List However, you should pay attention to the inertia of load. Regards!! Matias
Matise87 Posts: 3 Rating: (0)
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