Toshiba MCY-MHP0305HT-C Service Manual page 27

Item Description of operation, numerical data, and other information
7. Frequency High pressure release control
release This function is to correct the operation command of the compressor and suppress the
control rise of high pressure.
1) Control contents
The operation frequency is decreased by 1 step when Pd pressure
It is decreased by 1 step every 10 seconds until Pd pressure drops below 3.4 MPa.
2) Release condition
When Pd pressure
When refrigerant recovery control starts in all heating mode
During defrost operation, stop, thermo OFF.
8. IPDU IPDU controls inverter compressors by issuing commands relating to compressor
control speeds, speed increases / decreases, and current release control values via the
interface P.C. board.
The main control functions of the IPDU P.C. board are described below.
1. Current release control
To prevent inverter input current from exceeding the specified value, output
frequency is controlled with AC input current as detected by T611 mounted on the
IPDU P.C. board.
Zone A: Compressors are operated normally.
Zone D: The current operating frequency is maintained.
Zone B: Operating frequency is lowered.
Zone C: The lowering of operating frequency is halted
Current control values for various outdoor units are shown below.
3.2 MPa
Current
Zone B
Zone D
Zone A
to maintain the current frequency.
Outdoor unit
I
1
HP capacity
3 21.2
4 21.2
5 21.2
26
28
3.4 MPa.
Zone C
I
2
20.7
20.7
20.7
Remarks