Danfoss AK-CH 650 User Manual

AK-CH 650 Capacity controller RS8ER302 © Danfoss 2016-02 101
In this section, there is a more detailed description of the com-
pressor combinations and the associated coupling patterns.
Sequential operation is omitted from the examples since the com-
pressors are only connected in accordance with their compressor
number (First In - Last Out principle) and only speed-regulated
compressors are used to ll capacity gaps.
Compressor application 1 – single step
The capacity distributor is capable of managing up to 6 one-step
compressors according to the following coupling patterns:
• Sequential
• Cyclical
• Best t
Cyclical operation - example
Here, all compressors are of the same size and the compressors
are cut in and cut-out in accordance with the First-In-First-Out
(FIFO) principle, in order to equalise operating hours between the
compressors.
- There is operating time equalizing between all compressors
- The compressor with the fewest running hours starts rst
- The compressor with the most running hours stops rst.
Best t - example
Here are at least two compressors are of dierent sizes. The capac-
ity distributor will cut in and cut-out the compressors to produce
the best possible capacity t (the least possible capacity jump).
- There is operating time equalizing between the compressors 1
and 2 (same size in example).
- There is operating time equalizing between the compressors 3
and 4 (same size in example).
Compressor application 2 – 1 x unload + single step
The controller is able to control a combination of one capacity
controlled and multiple single step compressors. The advantage
of this combination is that the unloader valves will be used to ll
in capacity gaps and thereby achieve many capacity steps via few
compressors.
Preconditions for using this compressor application are:
• All compressors are the same size
• The capacity-regulated compressor can have up to three unload
valves.
• The main step and the unload valves can be dierent sizes, i.e.
50%, 25% and 25%.
This compressor combination can be handled in the following
coupling patterns:
• Sequential
• Cyclical
General regarding Handling:
Cutin
The capacity-regulated compressors with unloader valves start
before one-step compressors. The capacity controlled compres-
sor will always be fully loaded before cutting-in of subsequent
one-step compressors.
Cutout
The capacity regulated compressor will always be the last to
stop. The capacity controlled compressor will always be fully
loaded before cut-in of subsequent one-step compressors.
Unloader valves
At cyclical operation unloader valves are used to close capacity
holes from the subsequent one-step compressors.
Anti-cycle timer restrictions
In case a capacity controlled compressor is prevented in start-
ing due to anti-cycle timer restrictions, then the start of any
subsequent one-step compressors is not allowed. The capacity
controlled compressor is started when the timer restriction has
expired.
Cyclical operation - example
The one-step compressors will be cut in and cut-out in accordance
with The First-In-First-Out (FIFO) principle in order to equalise
operating hours between the compressors.
- The capacity controlled compressor is the rst to start and the
last to stop.
- Unloader valves are used to close capacity holes
- There is operating time equalizing between the compressors 2
and 3 (same size in example).
Appendix A – Compressor combinations and coupling patterns

Danfoss AK-CH 650 Specifications

General

Brand	Danfoss
Model	AK-CH 650
Category	Controller
Language	English