Electra DELTA 25, Service Manual

Page: 31 / 75

11-4
CONTROL SYSTEM
Revision Y05-01 Service Manual - Delta DCI
11.1.1 EEV (electronic Expansion valve) Control
EEV opening is defined as EEV = EEV
OL
+ EEV
CV
EEV
OL
is the initial EEV opening as a function of the compressor frequency, operation mode, unit
model and capacity.
EEV
CV
is a correction value for the EEV opening that is based on the compressor temperature.
During the first 5 minutes of compressor operation EEV
CV
= 0.
Once the first 5 minutes are over, the correction value is calculated as follow: EEV
CV
(n) = EEV
CV
(n-
1) + EEV
CTT
EEV
CTT
is the correction based on the compressor temperature. A target compressor temperature is
set depending on frequency and outdoor air temperature, and the actual compressor temperature
is compared to the target temperature to set the required correction to the EEV opening.
11.1.2 Reversing Valve (RV) Control
Reversing valve is on in heat mode.
Switching of RV state is done only after compressor is off for over 3 minutes.
11.2 Fan Mode
In high/ medium/ low indoor fan user setting, unit will operate fan in selected speed.
In AutoFan user setting, fan speed will be adjusted automatically according to the difference
between actual room temperature and user set point temperature.
11.3 Cool Mode
NLOAD is calculated according to the difference between actual room temperature and user set
point temperature by PI control.
In high/ medium/ low indoor fan user setting, unit will operate fan in selected speed.
In AutoFan user setting, fan speed will be adjusted automatically according to the calculated
NLOAD.
11.4 Heat Mode
NLOAD is calculated according to the difference between actual room temperature and user set
point temperature by PI control.
In high/ medium/ low indoor fan user setting, unit will operate fan in selected speed.
In AutoFan user setting, fan speed will be adjusted automatically according to the calculated
NLOAD.
11.4.1 Temperature Compensation
4 degrees are reduced from RT sensor temperature reading (excluding I-Feel mode), to
compensate for temperature difference between high and low areas in the heated room, and due
to coil heat radiation on RT sensor.