Mitsubishi Electric CITY MULTI PUHY-400YMF-C Service Handbook page 93

[1]-4 PUHY-600·650·700·750 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
setting of each LEV opening, requiring approx. 2 minutes at the maximum.)
(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: Model 500 has capacity control switching, Model 400 does not).
• 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 0 and 5˚C in cooling mode and that the high pressure is between 1.76 and 1.96 MPa in
• The fluctuation of the frequency of the variable capacity compressor is as follows. It is performed at 3 Hz per
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. (On Model 500, the No. 2 compressor will be started in un-load operation.)
• Model 400: After the No. 1 compressor has reached 98 Hz, the No. 2 compressor stops
• Model 500: After the No. 1 compressor has reached 100 Hz, the No. 2 compressor stops
full-load.
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. (On Model 500, the No. 2 compressor will be performed in un-load operation.)
3
Switching from un-load to full-load of No. 2 compressor (Model 500 only)
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 (Model 500 only)
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 star ted.
-90-
heating mode.
No.3 No.1 No.2
Constant Variable
capacity capacity
unit unit
starts.
un-load or un-load