Lev Opening Correction By Suction Super Heat; Lev Opening Correction By Discharge Temperature; Lev Opening Correction By Gas Pipe Temperature - Mitsubishi Electric MSC-07RV Service Manual

1 LEV opening correction by suction super heat

(Suction super heat) = (Suction temperature) - (Evaporation temperature)
The LEV opening is corrected as shown in the following table.
LEV opening correction (pulse)
Suction superheat (S.H.) MXZ-18RV-
Cooling
more than 10
8 to10
7 to 8
5 to 7
4 to 5
4 or less

2.LEV opening correction by discharge temperature

The LEV opening is corrected to 55 pulse when it has been corrected consecutively 20 times due to the discharge
temperature (Td) of 60; or below, or when the discharge temperature falls below 35°C. When such a status
has continued for 10 minutes, the compressor stops and enters the 3 - minute time delay.
If the compressor stops five times during a continuous operation, the unit stops due to abnormality.
MXZ-18RV-
E1
Discharge
Cooling Heating
temperature (:)
more than 90
5
85 to 90
1
80 to 85
0
75 to 80
-2
70 to 75
-2
65 to 70
-2
60 to 65
-2
60 or less
-5 -12
For capacity class 12(13) or 18 in single-unit operation, the stabilized range shifts to the next higher level.
(
I. e. Cooling : 85 to 92
Heating : 80 to 91
3.LEV opening correction by gas pipe temperature (effective in cooling operation only.)
(1) Maximum correction width : +14 pulse
(2) Single correction width : 1, 2, or 3 pulse
(3) Control details
1) S.H. HEX of each operating unit is calculated by using the following formula.
S.H. HEX (i) = (Gas pipe temperature (i)) - (Evaporation temperature)
2) The minimum valve is selected from each S. H. HEX.
3) From S. H. HEX (i) calculated in step 1) and the minimum value obtained in step 2), the
difference of each S. H. HEX (∆S. H. HEX (i)) is calculated as follows.
∆S. H. HEX (i) = (S. H. HEX (i) - S. H. HEX (min))
4) Each LEV opening is controlled based on ∆S. H. HEX (i) obtained in step 4).
∆S. H. HEX (i) and LEV control width
Range of ∆S. H. HEX (i)
∆S. H. HEX (i) to 3 deg
3 to ∆S. H. HEX (i) to 6 deg
6 to ∆S. H. HEX (i) to 9 deg
9 to ∆S. H. HEX (i)
MXZ-32RV-
E1 E1
Heating Cooling Heating
40 15 20 10
30 10 15 10
30 10 15 10
16 5 7 5
8 3 0 0
0 0 0 0
LEV opening correction (pulse)
Two units or more
Discharge
Cooling
temperature (:)
10
20 more than 100
5
20 95 to 100
0
90 to 95
20
-2
85 to 90
2
-2
0 80 to 85
-5
-3 75 to 80
-5
-3 70 to 75
-5
70 or less
)
115
MXZ-32RV-
E1
For capacity class 07 or 09 in single unit operation
Discharge
Heating Cooling
temperature (:)
more than 100
10 10
95 to 100
10 10
92 to 95
5 10
85 to 92
5 5
80 to 85
0 5
75 to 80
0 0
70 to 75
-2 -2
70 or less
-2 -5
LEV variation for corresponding unit
0
+1
+2
+3
Discharge
Heating
temperature (:)
more than 100
10
95 to 100
10
90 to 95
10
85 to 90
5
80 to 85
5
73 to 80
0
65 to 73
-2
65 or less
-5