Daikin D-BACS, Design Manual

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1.5 Explanations of Power Proportional Distribution 265
Power Proportional Distribution (P.P.D.)
(2) The way to reduce errors
The error
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can’t be reduced, however this error is small and negligible, therefore so it can generally clear troubles if
excusing the reason caused to tenants.
The way to reduce the error
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will be described as follows.
As shown in the drawing below, when the relation between a wattmeter and indoor units are clear, “THE SETTING TO
MAKE GROUPING FOR POWER PORTS” should be carried out at the test run of intelligent Manager. (The actual site
job will be conducted by persons of service dept responsible for the test run.)
The power input to iPU can be counted with the proportional division system based on every input of the wattmeter. On
the above example, watts at W1 and watts at W2 are shared by indoor units #1~#5 and indoor units #6~#8, respectively.
(Before the test run, it is necessary to enter the exact power port No. on the address table.)
The above setting results in the followings:
W1 Count conclusive total for indoor unit #1~#5
W2 Count conclusive total for indoor unit #6~#8
(Except for the error at
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). However, since iPU watt input has just 18 ports, additional divisional counting is not possible.
Caution:
If management staff checks the watts in the procedure mentioned below, they would find the calculation to be incorrect
due to an uncomplete cycle.
(Example)
(1) May/24th, read wattmeter and records the watts at 10:00 am
(2) June/24th, read wattmeter and records the watts at 10:00 am
(3) When the count in a period of May/24th to June/23rd is printed out, the total value doesn’t meet the value detected
mentioned above on (2) - (1).
iPU stores the information collected in a period of 0:00 am through 23:59 pm as one day information as shown above.
It results in the fact that there are ten hours gaps between on the first day of the counting and on the last day of the count
in the above mentioned column of “Result of detection by management staff” and “Count result”.
As shown in the figure above, this error increases in the season from the intermediate forwarding to the season in which
airconditioning is highly required.
For more accuracy, it is necessary to compare with the value detected at 0:00 am.
Power supply
3 phase
Power supply
single phase
To other iPU
#1 #2 #3 #6 #7 #8 #4 #5
W1
W2
Outdoor unit
Tenant A Tenant C Tenant B
PC
Hub
iPU
Count result of iPU
Result of detection by management staff
Large
5/24
0:00 10:00
Detection (1)
10:00
Detection (2)
23:59
5/24 6/22 6/24
Little