Low Hz High Pressure Limit; Electronic Expansion Valve Control - Daikin MKS-T Series Service Manual

SiSG121917E
4.9

Low Hz High Pressure Limit

Outline
The upper limit of high pressure in a low Hz zone is set. The upper limit of the indoor heat
exchanger temperature is also set by the operating frequency. Zones are divided into three,
reset zone, keep zone, and dropping zone, and the frequency control is carried out according to
each zone.
Details
50/65/80 class
90 class
Note
Dropping: The system stops 2 minutes after staying in the dropping zone.

4.10 Electronic Expansion Valve Control

Outline
The following items are included in the electronic expansion valve control.
Electronic expansion valve is fully closed
1. Electronic expansion valve is fully closed when turning on the power.
2. Pressure equalizing control
Room Distribution Control
1. Gas pipe isothermal control
2. Dew prevention control for indoor rotor
Open Control
1. Electronic expansion valve control when starting operation
2. Electronic expansion valve control when the frequency changes
3. Electronic expansion valve control for oil recovery
4. Electronic expansion valve control when the discharge pipe temperature is abnormally high
5. Electronic expansion valve control when the discharge pipe thermistor is disconnected
6. Electronic expansion valve control for indoor unit freeze-up protection
Feedback Control
1. Target discharge pipe temperature control
Details
The followings are the examples of the electronic expansion valve control for each operation
mode.
Part 4 Functions and Control
A
Reset zone
Highest indoor
heat exchanger
temperature
among
operating rooms
A (°C) B (°C) C (°C)
56 55 52
57.5 56.5 53.5
Control Specification
Dropping zone
B
Keep
zone
C
(R14587)
84