Variable drive versus two paralel compressors

[baycuclaudyu]

Hello all,

After an nice technical discussion, I came with an interesting topic.
What you prefere ?
An new and economically system - VFD or an clasicaly two reciprocating compressors master/slave.
Personally I agree the first system type - more eficiency and reliable.

Please add your real reason accordingly with customer needs:
- best price

- best quality


Waiting for your comments.

[chilliwilly]

I don't really have a preference, with me its all about horses for causes.The parralell system can have advantages over VVF other than costs. In the terms of reliabillity the parrallel system may be better, and could be improved to work almost as good as a vvf.

The master compressor could be fed from a multi tapped auto transformer and switched by contactors depending on the system demand. And when the master is at full demand, the slave could be switched in, then the master could run to a desirable running capacity maintaining a good efficiency.

In the long run a traditional system controlled like this would be more economical to repair than a VVF, and no mysterious parameter terminology programming needed. Just good old panel wiring and a bit of technical imagination.

In the case of a vvf the wiring is much simpler (should be but can get complicated in some applications), and is by no doubt much more efficient than any other drive method. But cost over quality seems to be the norm when manufacturers build their systems. Even the Mits invertors aren't as good as they used to be but are probably the best value for money.

Which in turn can cause undesirable results and embarrasment for us engineers who have sold and or installed a system. Leading yours or your bosses customer to think they've been fannied.

[RANGER1]

[QUOTE=baycuclaudyu;255096]Hello all,

After an nice technical discussion, I came with an interesting topic.
What you prefere ?
An new and economically system - VFD or an clasicaly two reciprocating compressors master/slave.
Personally I agree the first system type - more eficiency and reliable.





Please add your real reason accordingly with customer needs:
- best price

- best quality

So what type of compressor/s are you going to use on VFD, the same?

If you use one compressor on VFD & it breaks down, then what?

What would be your load/unload/speed stategy be, usually fully loaded at minimum speed,then ramp up.

VFD do use more power than non VFD.

VFD are good for turn down, if thats what you need.

Non VFD is simpler & more reliable, especially when something goes wrong!

I think you have to have a good reason to instal a VFD on reciprocating system, as they a very efficient
if you have enough load steps on compressor ie 8 cylinder with 2,4,6,8 cylinder loading etc