Hitachi YUTAKI Series - Defrost Operation Control

147
Safety and control device setting
SMGB0066 rev.0 - 12/2009
Controller pack
Service Manual
4
Hot Gas Bypass OFF
Hot gas Bypass OFF
Compressor Frequency
70 Hz Output
Compressor Frequency
60 Hz Output
Defrosting Finish
ConditionFullled
60 sec passed
after(*1)?
6 min passed from
desfrostingstart?
Pd≥3.6MPa?
 
Compressor Frequency
40HzOutput(*1)
10 Sec Count
Hot Gas bypass Solenoid
Valve (20G ON)
1 Sec Count
Fanstop,4-wayvalveswitching
Mainexpansionvalve“apulse”*2
10 Sec Count
Compressor Frequency
Retention
*Fan1stepoperationstart
Defrosting
ConditionsFullled
Compressor Real
Frequency=40Hz?
Tr≤-2ºC?
Tr≥-2ºC?
Ps≥1.0MPa?
1 min passed from
defrostingstart?
3 min passed from
defrostingstart?
Tr≤-10ºC?
Faninoperation?
Pd≥3.0MPa?
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
Yes
No
<Start Defrosting>
<Anti-Defrosting at
Liquefaction>
*Atoperationstart,6-stepoperationfor10seconds
and 1-step operation thereafter
<Prevent Ps Over-increase by
Hot Gas>
<Anti-Defrosting when Empty>
<Anti-Defrosting at
Liquefaction>
No
No
No
No
No
No
No
No
No
No
No
Fan OFF if in operation

note
For desfrosting, operate at the compressor frequency shown in -
the defrosting ow chart (without applying upper/lower limit).
Liquid injection shall be OFF at desfrosting. -