0-5 vdc to 0-10 vdc question 1

[zjade]

I have a analog output from a plc which is 0 to 5 vdc. I am driving a dc drive which has a 0 to 10 vdc input. My drive is now only seeing half speed. What is the fix and where can i get it.

Thanks

 

[dydt]

you will need an isolator voltage multiplier/divider board....there might be another term for this but anyway its a board that you can scale your input voltage to your requirement..

dydt

 

[electricuwe]

You might try to fix the problem with the parameter setting of the drive if its a drive with a digital control unit.

 

[buzzp]

Sujja suggested an op amp with a gain of two. That would
work but you will need a supply hooked to the op amp of at
least 10VDC (probably more unless get rail to rail op amp).
If this is a problem (no 24VDC available or 12VDC) then a DC-DC converter may work. This would depend on how quickly the changes will be occurring but would not likely cause a problem.

 

[cbarn24050]

Hi, if you use a low current op amp then you can use the drive's 'pot' voltage as the supply.

 

[TheDOG]

Scale it in the PLC or if the drive can accept a 0-20mA signal, why don't you put a 250ohm resistor in series with the drive? This will give you a 0-20mA signal proportional to your 0-5V DC signal. You will need to check the burden of the drive versus the PLC output rating, and also the minimum voltage signal accepted by the drive.

 

[pwrengrds]

The drive should be able to be programmed to go to twice speed over full range. Since you need to go full speed over half range it should work out correctly. If you want to avoid overspeed in this condition you could also program the max voltage to your upper limit. Most digital dirves are able to be programed this way. Another way is to decrease the field current, but this would also cause a loss of torque.

 

[ctolbert]

zjade:

Verify as well, that there is not a jumper on the plc card that allows you to change to a 0-10 vdc signal. Quite a few analog cards have this capability.

IMHO, I would get a signal conditioner or just change the card to a standard 0-10 vdc signal. Do not create a potential hassle for you later. Redlion and Action Instruments have fairly inexpensive condtioners.

Carl