VFD Mitsubishi Issue

[zai_jnr]

Dear members,

I'm now working with VFD ( Inverter) from mitsubishi.
The spec for the inverter is FR-A520-5.5K ( for 5.5kW motor).
The application for this motor is hoisting process.
For this application, the inverter using with brake resistor spec 300w and 100ohm. I'm face the problem with overcurrent fault each time motor want to stop.
Error will come out when there have any increasing or decreasing speed of motor.
From manual, I need to set parameter 30 to 1 value and parameter 70 to 10% value when using external brake resistor. The system working as normal without load but over current fault when there have load..
What i need to do now? Anyone from this forum can help me?

 

[DickDV]

There's lots of missing important information here but, generally, display the motor current on the drive and watch it. If the current goes high enough to cause the faulting and the motor performance causing the current is necessary to your process, then your drive is too small.

I don't have the spec's for the Mitsi drive but it is likely that the drive you have is only capable of 10% short-term overload. On most hoisting applications, that would be two sizes too small. I would normally want to see about 200% overcurrent capacity on the drive compared to the motor FLA.

 

[zai_jnr]

There's lots of missing important information here but, generally, display the motor current on the drive and watch it. If the current goes high enough to cause the faulting and the motor performance causing the current is necessary to your process, then your drive is too small.

I don't have the spec's for the Mitsi drive but it is likely that the drive you have is only capable of 10% short-term overload. On most hoisting applications, that would be two sizes too small. I would normally want to see about 200% overcurrent capacity on the drive compared to the motor FLA.

Dear DickDV,

Thanks for your reply.
Actually parameter 30 is for regenetive function selection and parameter 70 is for special regenetive brake duty.
According to manual, if I'm using external brake resistor,
I need to set this to parameter param30 : 1 and param70: 10%. For this case, I'm really concern regarding spec brake resistor that i'm use is under spec due to in manual there have stated that spec need to use is 110ohm but never inform Watt for the device ( for drive 5.5kW) . Let say, spec that I'm using is under spec and I am still want to use this brake resistor. There have any parameter setting need to consider to rectify this problem.

I'm not sure how to calculate brake resistor spec for drive.
There have some info in internet but not I'm understand with the term.
Below is link to Mitsubishi inverter manual.
You can retrieve the file from this link.

http://www.sendspace.com/file/n5erz2

 

[parky]

A hoisting process should that not hace a brake (mechanical)?
If it has then this could be the problem.

 

[Steve Wiebe]

Try increasing the decel time (parameter 8) and do an auto-tune as well (I forget how).
We get Arrow Speed to spec drives, resistors, reactors, .... and help with any issues we have (www.arrowspeed.com).
Steve.

 

[zai_jnr]

A hoisting process should that not hace a brake (mechanical)?
If it has then this could be the problem.

i think in my case there not hack the brake. I'm really concern about my brake resistor spec using, maybe it under spec,but I'm cannot to confirm it because don't know how to calculate the spec for brake resistor.

Anyway thanks for your reply.

 

[zai_jnr]

Try increasing the decel time (parameter 8) and do an auto-tune as well (I forget how).
We get Arrow Speed to spec drives, resistors, reactors, .... and help with any issues we have (www.arrowspeed.com).
Steve.

I'll try your suggestion. Existing setting for decel time was 2 sec.. maybe I'll try to set to 5 sec. What do you think?

Auto tune? Erm..what tune need to set for auto? Sorry, never use this function before.Hopefully when you recall the method, please feedback to me in this thread.

I just can change and try the setting by next Saturday due to this week and next week production running as a normal. So cannot to try or testing the system yet.

Anyway thanks for your reply.

 

[Steve Wiebe]

Lots to know about auto-tuning.
I'm not an expert and the manual really sucks.
The section in the manual starts at page 109.
Basically, you enter the motor data and auto-tune
(Enter 1 in parameter 96 and wait 25 seconds.If all goes well, value should be change to 3).

A little drive like a 5.5K may already have an internal brake resistor
and may or may not need an external resistor and/or brake module
(I'm not sure off the top of my head). When I'm back at work, I can check some prints.
Steve.

 

[Clay B.]

i think in my case there not hack the brake. I'm really concern about my brake resistor spec using, maybe it under spec,but I'm cannot to confirm it because don't know how to calculate the spec for brake resistor.

Anyway thanks for your reply.

Brake resistor watage is based on several factors. Main factor is duty cycle. Best thing to do is contact your drive vendor and they can size the resistor for you.

I have not done a hoist in some time but I seem to remeber them using Mechanical brakes not dynamic if they used any brake at all.

 

[rpoet]

Clay B,
I work in the special effects industry, and we often use winches with induction motors and VFDs for lifting and flying performers. We use the motor brake and a redundant brake only for holding, not for stopping. We rely on the VFD to decel the load. When specing the components for a winch, I will typically use the brake resistor recommended by the drive manufacturer.

zai_jnr,
If you're having trouble with your drive, you might try contacting your local Mitsi distributor. I've found those I've dealt with to be very helpful. They should be able to help you size your brake resistor properly, and also give you wattage and resistance values too if you need you need to use a third-party resistor.

-rpoet

 

[zai_jnr]

Dear All,

Thanx a lot for your feedback to this post.. Your helping really help for. Issue solve at last weekend.. .Last weekend I went to support my member to solve the problem. I checked one more time parameter setting inverter that set by this guy. What I found out is the setting is got mistake..Should be parameter 70 need to set 10% but that guy set to 1%. ...After reset back the parameter 70 to 10%...Issue was solved....Thanx a lot to all who give me an idea to solve this problem...