TM_i-BX(-N)_NC05_00_06_20_EN
MEHITS S.p.A.
●
TECHNICAL MANUAL
Version NC05 - Translation of the Original Instructions
37
Below are the various preventive actions relating to the operating limits; action 1 refers to the control action (before leaving the envelope); action 2 is
the limit action (operating point outside the envelope).
CAUTION:
DO NOT CHANGE THESE PARAMETERS.
THESE ARE MACHINE CONSTRUCTION PARAMETERS.
4.4.3.1
High compression ratio prevention (zone 2)
The high compression ratio is a compressor thermal limit: to ensure the control of the discharge temperature, a specific algorithm first slows down
the power increase, and stops it when it reaches the control setpoint (5°C below the maximum limit); if the temperature increases further, the
control algorithm gradually and slowly manages the power reduction, imitating the thermal inertia behaviour of the compressor, and finally shuts
down the compressor. The algorithm management parameters are
138V
,
138W
,
138X
,
138Y
.
Action distance
T
Discharge
(°C)
Control threshold
Power reduction
Limit threshold
Compressor block
Power increase speed reduction
(progressive)
Normal operation
Hz
→
f
(demand, envelope position)
Device
Description
Compressor
1.
Decrease of the power increase speed
2.
Power reduction
Exv
-
4.4.3.2
High condensation pressure prevention (zone 3)
Custom zone 3 is only considered if the value of parameter P131l is more restrictive than the limit of zone 3 defined by the manufacturer. The actions
will in any case be the same for both zones.
Device
Description
Compressor
1.
Decrease of the power increase speed
2.
Power limitation
Exv
-
4.4.3.3
High motor current prevention (zone 4)
Device
Description
Compressor
1.
Decrease of the power increase speed
2.
Power limitation
Exv
MOP with specific algorithm
4.4.3.4
High evaporation pressure prevention (zone 5)
Device
Description
Compressor
1.
Decrease of the power decrease speed
Exv
MOP
4.4.3.5
Low compression ratio prevention (zone 6)
Device
Description
Compressor
1.
Decrease of the power decrease speed
2.
Power increase
Exv
Variable MOP
