Building lift application with ACS 550

[Pafi]

Hello!
I need help from someone experienced with an application for merchandise lifting between different floors of a storage facility.
I am using an ACS 550 from ABB, motor power is 5.5kW and the inverter was chosen for heavy duty application. The motor has a built in electro-mechanical brake to be activated when reaching the chosen floor.
Problem is that I have no experience with lift application and from ABB representative they told me that only ACS 800 can be used for this application. I cannot believe that because ACS 550 is a very powerful inverter and theoretically can be used for almost everything. Maybe there is a built in MACRO for lifts/ cranes in ACS 800 but this application should be built with ACS 550 as well.
Someone with experience in lift applications can give me a hint about how shall I proceed, which are the condition to be met regarding the moment of start/ stop to co-ordinate starting/ stopping the motor with energising the brake, etc.
Thank you!

 

[waross]

A lift application will be regenerating 50% of the time. You must use a drive that will accept regenerated energy.
respectfully

 

[Skogsgurra]

It is usually not advisable to use a frequency inverter without a real good flux vector system and an encoder for lift applications. The ACS 550 has an encoder option (OHDI-01) but seems to lack a flux vector mode of operation - that may be why your supplier says it shouldn't be used for elevators. I would be hesitant myself. I have not seen any ACS 550 in a lift application.

Gunnar Englund

http://www.gke.org

--------------------------------------
100 % recycled posting: Electrons, ideas, finger-tips have been used over and over again...

 

[ozmosis]

Pafi
If somebody from (or representing) the company are saying "don't use the ACS550, use the ACS800", I would go with their advice on an elevator.
The dynamics of an elevator are quite severe and if it goes wrong, then it is usually a 'big' wrong.
As waross points out, you have the aspect of regeneration to contend with. Depending on the length of drop and the design of your elevator (are you using counter-weights etc) then the energy that has to pass through the braking chopper and into the brake resistors will be very high and constant. The resistors will get very hot and the brake chopper will be handling high current.
Also to be aware of are the issues about starting the elevator. You can't just release the motor brake and start the VFD otherwise your load (elevator) will drop. The moment you release the motor you must have generated the required torque in the motor to ensure it will lift without dropping. This also requires high performance between the VFD and motor.
For something that can potentially go very wrong, I would heed their advice. It's quite a specialised business in this sector and while the ACS550 might work ok, it could be problematic.
However, I know there are ABB guys in this forum who will know this product inside out, so see what other tips comes along from them.

 

[dpc]

My (limited) understanding is that the ACS 550 does has flux vector control of some kind, but not ABB's top-of-the-line "Direct Torque Control" (DTC).

I agree that you should go with manufacturer's advice on something like a drive for an elevator. If the drive supplier won't stand behind the application, where does that leave you if there's a problem?

 

[Pafi]

Yes, normally this is the way you should do (ask and follow representative advise).
But ACS 550 has sensorless vector and flux vector built in and I saw in the User manual of ACS 550 that it has an option to energise an output relay when the motor flux - and torque - reaches the rated value. Also there are indications regarding choosing the brake resistor for an overhauling load. Normaly all these are required for a lift application (control signal for ascending when motor torque is the rated one so the load will not drop after de-energising the brake and resistor braking in descending mode when the gravity will "overhaul" the motor).
Of course that a regenerating brake will be better, but I have the inverters and they cost some money.
Thanks!

 

[dpc]

If I understand correctly, this lift will not carry people, only freight? If this is the case, I might go along with you. But if it is to carry passengers, I wouldn't take the chance.

 

[jraef]

From your latest response it appears as though you understand the pertinent issues. Had you not shown that I would have strongly cautioned you against trying. So what I see you questioning now is, why doesn't ABB support this concept?

My take on it, working for a manufacturer for the last 12 years, is that they cannot ASS-u-me anything about the user when it comes to application knowledge or expertise. Not only that, but they have no way of knowing if the lift is for freight or people. In fact you do not either, in spite of your knowledge of the situation; who knows if someday, long after you are no longer involved, someone gets on and gets hurt. Nobody will bother trying to find you, but ABB's name is all over the product.

So from a liability standpoint, ABB tries to limit their exposure by having specific recommendations and application macros; program sub-routines and feature combinations that they feel will work best in spite of their not knowing specifics of the application. In this case, they only felt most comfortable doping that with their top of the line product. I can't blame them for that.

That said, it does not mean that the ACS550 will not be capable, but it does mean that you are on your own in trying to do it with that drive. You cannot expect ABB to support you on something they don't feel comfortable with. In other words, if you want their support for this you would need to follow their rules.

 

[Pafi]

OK, thank you, I understand.
First, the lift is not for people.
Then, I only made the job to put them into the cabinet - on specific order to do that - taking care of the manufacturer recommendations for protection, wiring, etc.
Now, my client, who is a company dealing with automation and control is facing this situation and they asked me for an oppinion. I made some thinking but I didn't have any practical experience in that matter so I asked here. And I'm not there to give a try following my ideas (cabinet have been exported abroad).
regards,
Pafi

 

[DickDV]

While both the 550 and the 800 can probably be made to work acceptably (both have flux vector capability with a proper encoder), the 800 has much better regulation of motor torque at near-zero speeds and would be much preferred.

For freight purposes, I believe that the 550 can be made to operate acceptably especially thru the use of the level detection features and pickup/release time delay capabilities of the output relays but, as above, I would far prefer the 800 for nice smooth torque transition and regulation at slow speeds.

 

[electricuwe]

Usually inverters for elevators are purpose designed units because in such kind of application the IGBT-modules are subjected to very severe power-cycling conditions compared to other drive applications. Power cycling is a stress on power semicondcutors that causes failure due to bond wire lift-off after exposing the semiconductor chip to a number of changes in junction temperature.

Using another kind of drive in a elevator application (or compareable application) may lead to premature failure.