bitzer compact screw compressor

[mo_eng]

hi ll)

i use four compact screw type compressor(bitzer brand) in a chiler and i dont have any idea for capacity control(it has four step unloader)
do you have any experience with bitzer compact screw compressor?

 

[P.d.L.]

It is quite simple (isn't everything when you know how )

http://www.bitzer.de/eng/product/list/prod4/dcode/SH-170

See chapter 2. Are you using a frequency inverter ? If so you don't need to use CR1/CR2, only CR3 to unload at startup and CR4 pulsating to return the oil.
If you don't have an inverter you can either use step capacity (25%/50%/75%/100%) or infinite control (by pulsating CR3/CR4 you control the slider).
Usually infinite control provides better accuracy and is good for quick reaction, like regulating chiller outlet temperature.
Step capacity is good for slow response, like regulating on chiller inlet temperature.
Hope this helps!

 

[mo_eng]

thank you a lot p.d.l
but can you more explane step capacyty control ?

 

[P.d.L.]

thank you a lot p.d.l
but can you more explane step capacyty control ?

Have you read the manual? What don't you understand?

 

[mo_eng]

have you read the manual? What don't you understand?

i cant download the manual.

 

[P.d.L.]

Try this link.

http://www.bitzer.de/download/download.php?P=/doc/&N=sh-170-3.pdf&ccode=EN

 

[mo_eng]

logic

i cant understand !!!
i have a four stage thermostat for control four compressor.
now i cant undrestand how can i do that?
i dont have any experience with this compressors.

 

[P.d.L.]

What is your control input for loading/unloading capacity?

 

[mo_eng]

What is your control input for loading/unloading capacity?

i have a one digital input for capacity control.(from stage one thermostat)
now i dont know how i can 4 step control with only one digital input?