Appendix 2: Advanced Functions; Skip Defrost; Variation Of The Defrost Interval - Carel ir33+ small wide User Manual

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11.1 Skip defrost

This algorithm is used to determine whether the shorter duration of a
defrost allows subsequent defrosts to be skipped. To enable the function,
set d12 = 2 or 3.
Par. Description
d12 Advanced defrosts
d12 Skip defrost Automatic variation of dI
0 Disabled Disabled
1 Disabled Enabled
2 Enabled Disabled
3 Enabled Enabled
dn Nominal defrost duration
dH Proportional factor for variation of dI
dP1 Maximum defrost duration
dP2 Maximum aux evaporator defrost duration
The nominal defrost times on evaporator 1 and evaporator 2 (auxiliary
evaporator) are determined based on parameter dn and the parameters
that set the maximum defrost duration for evaporators 1 and 2, according
to the following formulae:
dn1 =
dn2 =
The algorithm keeps a counter of the defrosts to be skipped:
•
if the defrost ends after a time less than dn1, the counter of defrosts to
be skipped is increased by 1;
•
if the defrost ends normally, the next defrost is performed;
•
when the counter reaches a total of 3, 3 defrosts are skipped and then
the counter returns to 1;
•
when powering on the controller, 7 defrosts are completed without
increasing the value, after which the counter is enabled (starting from
the eighth defrost).
Note: if there are two evaporators, the defrost duration used to
determine the defrosts to be skipped is the longer nominal defrost
duration.
ir33plus +0300028EN rel. 1.1 - 05.05.2017

11. APPENDIX 2: ADVANCED FUNCTIONS

Def Min Max UOM
0 0 3
65 1 100 %
50 0 100 -
30 1 250 min/s
30 1 250 min/s
Tab. 11.a
dn
dP1
100
dn
dP2
100
Possible operating sequence (for example, if d12 = 2):
Start count Skip count
7 0
6 0
5 0
4 0
3 0
-
2 0
1 0
0 0
0 0
0 0
0 0
0 0
0 1
0 1
0 0
0 0
0 0
0 1
0 1
0 2
0 2
0 2
0 0
0 0
0 0
0 0
0 1
0 1
0 2
0 2
0 2
...

11.2 Variation of the defrost interval

This algorithm is used to adjust the defrost interval based on the duration
of the previous defrost. To enable this, set d12 = 1 or 3.
The nominal defrost times on evaporator 1 and evaporator 2 are
determined based on parameter dn and the parameters that set the
maximum defrost duration for evaporators 1 and 2, according to the
following formulae:
With running the defrost, depending on the duration "dE", the defrost
interval "dI" is adjusted by the value "ΔdI", calculated using the algorithm.
If there are two evaporators, the defrost duration considered is the longer
nominal defrost duration.
52
Current count Defrost
0 Performed
0 Performed
0 Performed
0 Performed
0 Performed
0 Performed
0 Performed
0 Performed
0 Performed
0 Performed
0 Performed
0 Performed
1 Skipped
0 Defrost
0 Performed
0 Performed
0 Performed
1 Skipped
0 Defrost
2 Skipped
1 Skipped
0 Defrost
0 Performed
0 Performed
0 Performed
0 Performed
1 Skipped
0 Defrost
2 Skipped
1 Skipped
0 Defrost
dn
dP1
dn1 =
100
dn
dP2
dn2 =
100
Outcome
Not tested
Not tested
Not tested
Not tested
Not tested
Not tested
Not tested
> "dn"
> "dn"
> "dn"
> "dn"
< "dn"
> "dn"
> "dn"
> "dn"
< "dn"
< "dn"
> "dn"
> "dn"
> "dn"
> "dn"
< "dn"
< "dn"
< "dn"
Tab. 11.b