Compressors short cycling

[JohnEchiller]

I have a four circuit 140 ton air-cooled chiller with 4 35 ton Bitzer compressors. This unit has approximately 30% load. I am trying to set the band control on my M172 to control compressor staging. This is the problem I'm running into.

Set point is 60F 

No matter how I set my Band 1 and Band 2 settings I will have all four compressors cycle approximately every 10 minutes and then pull down beyond set point then all four compressors will shut off. After my delay on break timer all four compressors will again cycle on.

I believe I understand how the band settings work but I am not able to control the compressor staging without short cycling.

After the second compressor starts, the process temperature begins to decrease but doesn't go below band One temperature set point before the next compressors start. Why would I want to stage on more compressors when my temperature is decreasing. I have tried every Band temperature and increment and decrement timers settings but I still have extreme compressor short cycling. I believe there is a serious flaw in in the Schneider function block for band control. 

Why would you want to have the band one-timer start before the first stage is energized. Then automatically start other compressors until you are below band One temperature set point. We are looking at writing our own staging program but I feel like I would like to understand why Schneider runs their band control setting this way. It's a very inadequate way to stage on multiple circuits. Very little control.