Daikin J Series Service Manual download pdf (Page 82)

SiE18-201 System control

Main Functions 71

3.6.3 Determination of Initial Frequency

Initial frequency setting (determination of initial operating frequency based on S value and ∆D

signal (α value))

Outline When the compressor starts and when a change occurs in the conditions such as change of

room unit operations, the sum of the maximum α value (MAXα) of each H/U unit, the total of S

values of operating indoor units (ΣSU) and the total of S values of non-operating room units

(ΣST) is used for the frequency initialization.

(Addition of non-operating room unit correction to S value classification)

Non-operating room unit refers to an indoor unit with thermostat OFF.

To ensure appropriate capacity supply in accordance with outside temperature, correction is

provided based on the outside temperature.

Furthermore, for improved startup in heating cold start, frequency correction is provided based

on the detection of cold start or hot start (change in the number of rooms) using the discharge

pipe temperature.

Description Determination of S value classification

The sum of S values sent form each BP unit of operating rooms (ΣSu) and non-operating rooms

(ΣST) are used to determine the S value of outdoor unit (system).

For cooling: ΣS= ΣSu

For heating: ΣS= ΣSu + 0.25 ~ ΣST

When S value changes in above case, the initial frequency is determined according to the

following matrix and set as FINI 1.

Note No change is made in ΣS during defrost control (FD = 1).

The frequency obtained by substituting FINI 1, outside air temperature and discharge pipe

temperature in the following equation is set as command frequency FSR.

Whereas,

Discharge pipe temperature DO ≥45˚C: KFIDO = 1

Discharge pipe temperature DO < 45˚C: KFIDO = 1.4

S value : Frequency constant

ΣS : Total of S value

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Daikin J Series Service Manual Page 82