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PTControl
03-07-2013, 08:13 PM
Hello.

It's possible to read actual capacity (slide position + vi slide position => capacity) od analog output? I can't find engineering manual for Unisab II. My friends have only service manual. Someone know how can I take capacity form Unisab II or have engineering manual?

Thn for helps
Bye
PTControl

Josip
05-07-2013, 04:22 PM
Hi, PTControl :)


can you give some more data regarding compressor ....

it is possible to see all data on UNISAB II display if it's in working condition ... Vi position of course only if you have auto Vi ... it is shown in this menu ... SET UP-CAPACITY-Vi POSITION

in case of manual Vi you can read only capacity slide position after configuration&calibration ...

Hope this is of some help to you ...


Best regards, Josip :)

PTControl
06-07-2013, 10:27 PM
Hello Josip,

I asked about calculated capacity in % (slide position corrected by vi slide position) send to analog output Unisab II. It's possible? My coleque saw it's not possible, analog output is only for frequency converter - if is used for compressor... :-) I need this capacity to control few machine in automatic sequence control by PLC. I can do this with MyCom, Grasso, Frick, JC Unisab III, Gram or with my own local PLC for compressor. Only with Unisab II is my nightmare and only using Profibus DP card is solution to read capacity. But this card is exspencive ~ 2000 - 2500 euro netto with correct program upgrade for Unisab II.
And if you don't know this, maybe You have advanced manual for Unisab II - like this:

http://pl.scribd.com/doc/57345616/Unisab-II-0178-445-ENG-logo-1

Thx
PTControl

josef
08-07-2013, 04:53 PM
Hi PTControls, does not know if I understand your question, but keep in mind that Unisab has its own logic which solve it if you are an expert on PLC and understand the problem and compressors are many variations.

Josip
08-07-2013, 05:43 PM
Hi, PTControl :)


Hello Josip,

I asked about calculated capacity in % (slide position corrected by vi slide position) send to analog output Unisab II. It's possible? My coleque saw it's not possible, analog output is only for frequency converter - if is used for compressor... :-) I need this capacity to control few machine in automatic sequence control by PLC. I can do this with MyCom, Grasso, Frick, JC Unisab III, Gram or with my own local PLC for compressor. Only with Unisab II is my nightmare and only using Profibus DP card is solution to read capacity. But this card is exspencive ~ 2000 - 2500 euro netto with correct program upgrade for Unisab II.
And if you don't know this, maybe You have advanced manual for Unisab II - like this:

http://pl.scribd.com/doc/57345616/Unisab-II-0178-445-ENG-logo-1

Thx
PTControl

unfortunately, UNISAB II doesn't have analog outputs ... only analog inputs and you should read those data from temperature, pressure, capacity and Vi probe i.e. the same analog input into UNISAB II you can use for your input into PLC like SIEMENS, MITSUBISHI or other, but I think you need a card to read analog data ... and use those data to show capacity...

sorry for my ignorance, but, why you need this ... in my opinion UNISAB II is dedicated for close control of refrigeration compressors and can calculate Vi and then set required capacity and control many other states of unit/s much better then SIMATIC or similar PLC (my personal opinion, no need to agree with:p)... you just monitor those values and show on your PLC screen that should be enough ...

I cannot discuss the prices, but I think with UNISAB II or III you get value for money ... anyhow if sometimes we need some piece of hardware it is inevitable ... when we need interface (Profibus DP card) we have to install it or we can use a new piece of hardware with incorporated interface of course with another (new incorporated) price:p ... but to have something of value we have to pay for ...

I think, not sure, after May 2005 all UNISAB II are equipped with Profibus DP card and you need only a DP protocol ... maybe depend on delivery contract ...

I believe you are not satisfied with my answers/question, sometimes our wishes are off limits;)

You did not mention anything about your system ... type and number of compressors, UNISAB II version etc .... just curious for information ....



Best regards, Josip :)

PTControl
10-08-2013, 04:40 PM
So, thx for your answer Josip. I don't have nothification about new posts on this thread. :-)
I don't want to discuss the majority central control few screw compressors by PLC, or other logic - different like Unisab logic. In my opinion with central PLC we have more options to control, setpoints and other. It's my opinion. My company created new system for 30-40 factory which worked with central units dedicated for compressor - Stal Electronic, Multisab etc. I'm not mechanic, but person from this factory give me one important information - now screw compressor system working more efficency - I don't have any question, money talking more than every words.. :-)
PLC give me more operation to blokage start/stop machine, create group for few capacity of compressor. For different type of load: air cooler, tunnel I can change group priority. Sorry, but it's not possible for dedicated system.

Thx for manual for Unisab. It's not possible to take capacity using electricity standard signal. Only Profibus DP signal or second option -> "RSLAN" + Simatic S7-1200 from Johnson Control too. 1st and 2nd isn't cheap to buy, but it's cheap watching future costs using screw compressors system.

Segei
12-08-2013, 03:54 AM
I'm just wandering. How did person from the factory find that refrigeration system work more efficiently?

Josip
12-08-2013, 08:54 AM
Hi, PTControl :)


So, thx for your answer Josip. I don't have nothification about new posts on this thread. :-)
I don't want to discuss the majority central control few screw compressors by PLC, or other logic - different like Unisab logic. In my opinion with central PLC we have more options to control, setpoints and other. It's my opinion. My company created new system for 30-40 factory which worked with central units dedicated for compressor - Stal Electronic, Multisab etc. I'm not mechanic, but person from this factory give me one important information - now screw compressor system working more efficency - I don't have any question, money talking more than every words.. :-)
PLC give me more operation to blokage start/stop machine, create group for few capacity of compressor. For different type of load: air cooler, tunnel I can change group priority. Sorry, but it's not possible for dedicated system.

Thx for manual for Unisab. It's not possible to take capacity using electricity standard signal. Only Profibus DP signal or second option -> "RSLAN" + Simatic S7-1200 from Johnson Control too. 1st and 2nd isn't cheap to buy, but it's cheap watching future costs using screw compressors system.

You are welcome .... if you need further help or opinion do not hesitate to ask ... if not me someone will help somehow ...

I can agree, but only partially, with you ... we also use a central PLC system to monitor complete plant ... room temperature set points, defrosting, lights, doors, evaporator or condenser fans, pumps, group priority, etc, but for compressors control itself (start -stop sequence, capacity change, alarms, ramp up or down and other specific control of compressor -like set points, oil pressure, oil DP, suction superheat, discharge superheat, suction pressure-temp, discharge pressure-temp, dead band, neutral zone, auto Vi change, capacity control via el. motor power consumption control, etc..) I do not believe (with all my respect to you and your colleague programmers) that you can make a better algorithms than that within UNISAB --- it has dedicated programs for particular type of compressor and only for compressor and nothing else .... of course it is very important to configure communication within the whole system of compressors via UNISAB and people often are not very familiar with ... if this is not done correct all refrigeration circuits work incorrect i.e. expensive .... above is also my personal opinion and I'm not saying your system is bad :p.

Believe me, I know how hard is to optimize refrigeration plant ....

Best regards, Josip :)

Segei
12-08-2013, 02:08 PM
Usually, central PLC controls start, stop, load, unload of the compressors. The rest should be done by compressor PLC.