Compressor Regulation; Bldc Compressor Start-Up Procedure; Inverter Compressor Oil Recovery Function - Mitsubishi Electric i-BX-N Technical Manual

TM_i-BX(-N)_NC05_00_06_20_EN
4.4

COMPRESSOR REGULATION

The inverter compressor adjusts based on a P+I algorithm (type of regulation that can be selected using parameters 0506, 0509 and 0512 for
independent cool, heat and DHW regulation respectively), as a function of the temperature value read by the system exchanger output probe
(analogue input B2) (parameter 0637 "Type regulation plant=OUTLET"), or by the DHW storage tank probe (analogue input B3 reading), during the
production of system water in the first case, and DHW in the second.
The compressor safety times set with the parameter must be observed.
The working point of the compressor (suction pressure based on the delivery pressure) will be controlled constantly to prevent operation outside the
envelope.
INFORMATION:
when regulating the Nadisystem controller, the Td=0 constant of the PID cannot be changed using the parameter. Therefore,
only P or P+I regulations are possible (for the description of the PID regulation see the attached)
By accessing the system with the Service password, it is possible to view the main masks of the menu of the pldPro interface on board of the unit,
with information on the status of the compressor, the DHW and the system regulator value
For the default values of the various parameters, see the parameters table
4.4.1

BLDC COMPRESSOR START-UP PROCEDURE

i-BX and i-BX-N units use BLDC inverter compressors and POWER+ CAREL PSD1 or PSD2 drivers.
At start-up, the compressor is brought to rotation at the start-up speed (start-up speed as indicated by parameter 138G). This speed is maintained
irrespective of the regulation request for the whole duration of the minimum start-up time (parameter 1351). At the end of this period, the
compressor speed/modulation is automatically adjusted based on the request and consistently with the control conditions of the work point in the
envelope (see the Prevent actions paragraph).
4.4.2

INVERTER COMPRESSOR OIL RECOVERY FUNCTION

Thanks to parameter 134A = "enable oil recovery", it is possible to enable a function that allows to recover the compressor oil from the cooling circuit.
In view of parameters:
134B minimum compressor forcing threshold request
134C minimum compressor forcing speed
134D time of permanence before activating the oil function
134E compressor forcing speed
134F compressor forcing time
with 134B = 100%, if the compressor speed is less than parameter 134C for a period of time set in 134D, the compressor is forced at the speed set
by parameter 134E for the time in 134F.
With parameter 134B < 100% the active request will also be controlled based on the active setpoint.
Note: if during the forcing of the compressor for oil recovery the regulation setpoint set in heat, cool or DHW is reached, the compressor is kept on
until the expiry of 134F, or, if cold water is being produced, until the temperature of the water produced reaches the value of 0634 "antifreeze alarm
setpoint" + 0638 "antifreeze differential for oil recovery"
For the default values of the various parameters, see the parameters table
MEHITS S.p.A. ● TECHNICAL MANUAL
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Version NC05 - Translation of the Original Instructions