Daikin D-BACS, Design Manual

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256 1.1 System Architecture
Power Proportional Distribution (P.P.D.)
1. P.P.D. Design Guide
1.1 System Architecture
1.1.1 Confirmation of Watthour Meter
For distribution of electric energy, the integrating watthour meter with pulse transmitter is required.
It is important to confirm that the specifications coincide with each other, and also to confirm with the division in charge
(normally, electrical work division, not air-conditioning div.).
· Specifications of watthour meter to be connected to intelligent Manager
a) To be an integrating watthour meter with pulse transmitter.
b) The output pulse unit (pulse weight) is to be 1 pulse to 1kWh (1kWh/pulse).
c) The pulse width is to be within 40 to 400 milli-sec.
d) The electronic type relay is to be used for pulse output, and it to be no-voltage output.
If the specifications are not coincident, there is a possibility that the following imperfections are caused:
„
If the output pulse unit is not 1kWh/pulse.
It results a large difference between the reading (value) of watthour meter and the total value of distribution of electric
energy.
For the charge calculation, the number of pulse input is counted and the power consumption of the outdoor unit is
monitored, therefore, for example, if the large value, 10kWh/pulse, is inputted, the electric energy calculated is the
value of one tenth (1/10) times.
„
If the pulse width is not within 40 to 400 milli-sec.
If it is less than 40 milli-sec., the pulse input cannot be detected, and the result of calculation is smaller than the real
value.
In addition, if more than 400 milli-sec., more than 2 pulses is detected for 1-pulse input, and the result of calculation is
larger than the real value.
„
If use of contact other than electronic type relay.
If it is a general relay, the pulse may not accurately be detected due to relay chattering.
Confirm the following items for the construction process.
„
Construction of pulse signal line is kept away from power cables
For this pulse signal line, the voltage DC24V should be applied from the intelligent Manager side. It should be
constructed separating from the power cables.
„
Max. distance to be 200 m
Confirm that the distance with the watthour meter~intelligent Manager is within 200 m.