Anti-Recycle Timers CGAM

Issue:

Does the new air-cooled chiller have anti-recycle timers?

Resolution:

CGAM

• The CGAM is built standard with the CH530 controller
• The following are the non-adjustable timers:
  • Compressor Minimum On Time is 2 minutes (unless interrupted by limits or diagnostics)
  • There is a very short stop-to-start delay of 10 seconds enforced on each motor

• The Restart Inhibit algorithm decides the start to start time
• The Free Starts Setting is 2 and the Start to Start Time is 6 minutes.

What this means:

Imagine a bucket that can hold (Free Starts * Start to Start Time) units of water.  For example, with Free Starts = 2 and Start to Start Time = 6 minutes (360 seconds), the bucket can hold 720 units.  Every time a compressor starts, add Start to Start Time units to the bucket (360 units).  Every second thereafter, remove one unit per second from the bucket.  Now, suppose the compressor shuts down and want to start it again.  If the bucket is empty enough to receive Start to Start Time (360) more units without overflowing, the compressor is allowed to start.  If it would overflow, it is prevented from starting until the bucket wouldn't overflow.

If the bucket starts out empty:

• Start a compressor (bucket now contains 360 units).
• Wait 30 seconds (bucket now contains 330 units).  Shut down the compressor.
• Wait another 30 seconds (bucket now contains 300 units).  Try to start.  Bucket would not overflow, so start is allowed.  Bucket now contains 660 units.
• Wait 30 seconds (bucket contains 630 units).  Shut down the compressor.
• Wait another 30 seconds (bucket contains 600 units).  Try to start.  Bucket would overflow to (600 + 360 = 960 units).  Start is not allowed.  Must wait at least another (600 - 360 = 240 seconds) before it can start without overflowing the bucket.

Notes:

Changes:

Other Question/Problem/Cause Statements:

• Does the new air-cooled chiller have anti-recycle timers?
• What is the stop-to-start timer?
• What are the anti-recycle timers?
• What are the antirecycle timers?
• How long must each compressor run?
• Is there a minimum run time?
• What is the start-to-start timer?
• What is the compressor minimum on time?

Facts:

• Air-Cooled Chiller (Pueblo) (CGAM 20-130 Ton)