Mitsubishi Electric CITY MULTI PUHY-400YMF-C Service Handbook page 77

[1]- 3 PUHY-P600·650·700·750 YSMF-C
(1) Initial processing
• When turning on power source, initial processing of microcomputer is given top priority.
• During initial processing, control processing corresponding to operation signal is suspended. The control
processing is resumed after initial processing is completed. (Initial processing: Data processing in
microcomputer and initial
(2) Control at staring
• At startup, variable capacity unit operations will start first.
• For 3 minutes after starting, 60 Hz is the upper frequency limit. (When only No. 1 compressor is operating.)
• 75 Hz is the upper limit for the 30 minutes after the compressor has started operation.
• Normal control is performed after the initial start mode (described later) has been completed.
(3) Compressor capacity control
• Compressor is performed by the variable capacity compressor on the variable capacity unit (No. 1: inverter motor)
and constant capacity compressor (No. 2: It has capacity control switching).
• In response to the required performance, the number of compressors operating, the switching of capacity control
and the frequency of the variable capacity compressor is controlled so that the evaporation temperature is
between – 2 and – 6˚C in cooling mode and that the condensation temperature is 49˚C in heating mode.
• The fluctuation of the frequency of the variab
second.
20 to 100 Hz (TH6 > 20˚C in cooling mode, or in heating mode)
30 to 100 Hz (TH6 < 20˚C in cooling mode)
1) No. 2 compressor operation, stopping and full-load/un-load switching
1
Switching from stop to run of No. 2 compressor.
When the required performance cannot be obtained by only No. 1 compressor, the No. 2 compressor will be
started. (The No. 2 compressor will be started in un-load operation.)
• After the No. 1 compressor has reached 100 Hz, the No. 2 compressor stops
2
Switching from run to stopping of No. 2 compressor.
When the required performance is exceeded when the two compressors, No. 1 and No. 2, are operating, the No.
2 compressor is stopped. (The No. 2 compressor will be performed in un-load operation.)
3
Switching from un-load to full-load of No. 2 compressor.
When the required performance cannot be obtained by the No. 1 compressor and the No. 2 compressor operat-
ing in un-load, the No. 2 compressor will be switched to full-load operation.
4
Switching from full-load to un-load of No. 2 compressor.
When the required performance is exceeded when the two compressors, No.1 and No. 2 operating in full-load,
the No 2 compressor will be switched to un-load operation.
2) No. 3 compressor operation/stopping.
1
Switching No. 3 compressor from stopping to operation
When the required performance cannot be obtained with only the No. 1 and No. 2 variable capacity unit com-
pressors, the constant capacity unit No. 3 compressor will be started.
*The No. 3 compressor is equipped with a capacity control switching function. It starts with un-load operation
in the initial start mode and during defrosting, and starts in full-load operation at all other times.
setting of each LEV opening, requiring approx. 2 minutes at the maximum.)
le capacity compressor is as follows. It is performed at 3 Hz per
-74-
No.3 No.1 No.2
Constant Variable
capacity capacity
unit unit
un-load or un-load full-load.