Home
Главная
Daikin
Чиллер
EWWD900CJYNN
Инструкция оператора Страница: 20

Daikin EWWD900CJYNN [20/28] Description of the compressor capacity control

Daikin EWWD480CJYNN [20/28] Description of the compressor capacity control

040 Condenser pump maintenance Request of condenser pump maintenance M

041 Compressor maintenance Request of compressor maintenance M

050 Unit 1 offline A

051 Unit 2 offline A

052 Unit 3 offline A

053 Unit 4 offline A

055 32K Clock Board Fault Low charge, internal battery A

D01 EXV Driver sensor /input fault A

D02 EXV step motor error A

D03 EXV Driver Eeprom error M

D04 EXV Driver battery error A

D08 EXV not closed during power off M

6. Description of the compressor capacity control

Each screw compressor of the Frame 4 series, installs a sensor for the measurement of the compressor slide position.

Such position data is sent to the controller through a 4-20 mA proportional signal. The controller uses this signal to

control the logic of the refrigerated water system and the starting of the compressors. The minimum signal corresponds

to 25% of the volume capacity of the compressor while the maximum signal corresponds to 100%.

This type of sensor guarantees a linear response of the signal according to the position of the capacitive pole and has no

reset capabilities (see Figure a). To reset the slide position signal, it is necessary to access the software through the

keypad.

Figure (a)

6.1 Setting of the capacity transducer

Under the “Service” menu (protected by password) of the relevant compressor, once the request “adjustable sensor?”

appears on the display, just select “N”.

After this, the request to introduce the type of the installed compressor appears. Verify the compressor model on the

nameplate and input the information.

Once the compressor model information has been entered, the correction of the minimum and maximum values must be

made. Unload the compressor completely as previously described and verify, by means of the I/O key, that the measured

reference signal is 25%. If different from 25%, make the necessary adjustment of the measured value under the service

menu password (the screen next to the compressors setup). The same procedure must be carried out once the

compressor is loaded to 100%.

7. Water temperature Setpoint Reset

Among the controller’s options, there are also many possibilities to regulate the unit with particular logics or external

signals.

One of the functions that engineers and technicians find most useful, is the possibility to modify the local control

setpoint of the refrigerated water in accordance with the following logics:

1. Dual setpoint: Through an external contact (by customer), it is possible to change over the local setpoint of control

between two well defined values. Such option results advantageously applicable in case of installation with ice

bank. Such application normally requires a positive setpoint (e.g. 7°C) to be used in the daytime and a second

negative setpoint (e.g. -5°C) for the night time. Obviously, in the case that the water temperature at the evaporator

outlet is lower than 4°C, the correct amount of antifreeze must be added to the water system.

2. From external signal: By using an external 4-20mA signal, it is possible to modify the value of the local setpoint

within predetermined minimum and maximum limits.

3. From outside ambient temperature: This function, which can be enabled under the "User" password, allows to

modify the setpoint according to a defined external temperature range. A reduction of the external temperature

causes an increase of the control setpoint. Such system allows to economise energy when the outside temperature

drops under the design value.

Daikin EWWD900CJYNN [20/28] Description of the compressor capacity control

Содержание

Похожие устройства