Daikin BPMK928B42, Service Manual

Page: 124 / 410

Si18-201 System control
Main Functions 111
3.3 Standby Control at Power ON
Purpose of the
Function To initialize the motorized valve at power ON, to determine the valve opening degree and
promote pressure equalization, and to conduct a standby operation.
The reason for promoting pressure equalization at power ON is to prevent the compressor from
locking due to insufficient pressure equalization that could result if units are restarted
immediately after reset during operation (due to momentary power outage and others). The
standby operation collects refrigerant in the receiver to ensure sufficient oil level and dilution in
the compressor immediately after startup.
∗
The standby operation and pressure equalization are described in the next section.
Explanation of
The Function [Detail]
1. Compressor ON prohibit timer (60 seconds) starts when power is turned on.
P1 pulses is closed, and the current opening degree is set to 0 pulse (full closing process)
2. Compressor ON prohibit timer reaches the set time, a standby operation is activated.
Note When the compressor ON prohibit timer is in counting operation, operation of the compressor is
prohibited.
During standby operation, operation command from BP units are ignored.
Note Regarding initialization of BP motorized valves at power ON, refer to the section on BP
motorized valve full closing on page 153.
EVP
Power ON
P1
P2
Fully closed
Fully closed
Fully closed
EVL
P1
EVG
P1
Full closing
process
60 sec
Shifts to standby operation
or to stop status.
(M1004)
Compressor ON
prohibit timer