Compressor Normal Mode; Speed Control; Constant Speed Operation; H Side Start Condition （And) - Panasonic MDF-DU702VH Service Manual

２．Compressor normal mode
（Speed control）
(1)
Three type of comp. operation mode depending the chamber temp.
Chamber temperature

Speed control

(Constant speed operation)

The control method in the case of starting the comp. from the state where both the comp.s are stopped is
shown below
H side
L side
L side restart
L side
① H side start condition （AND)
・After the H side stopped, the threshold (3 min) elapsed
・（Immediately after H side start failure, 10 sec elapsed ）
・If the chamber temp.is higher than the set temp. plus the threshold (0.5 ° C)
② L side start condition（AND)
・After the L side stopped, the threshold (4 minutes) elapsed
・（Immediately after L side start failure, 10 min elapsed）
・A time longer than the threshold(※1) has elapsed after the H side start.
threshold (※1) condition
short(60 sec) Cascade temp. is below threshold (-20 ° C) and within 2 hours from the L side stop
long (480 sec) Other than those above
＜After security operation＞
・After the L side stop, the threshold(4 min) elapsed.
・After the H side start, 1min elapsed
・The cascade temp. is less than -34 ° C or 15 min elapse from the above
③ H side stop condition（OR)
・the chamber tempreture is lower than set temp.-threshold (0.5℃).
・(security operation)
④ L side stop condition(OR)
・H side stop
・Outside the initial startup period and the cascade temp. is higher than the threshold (-10℃)
⑤ Condition for L side restart（AND)
・After the L side stopped, the threshold (4 min) elapsed
・（Immediately after H side start failure, 10 seconds elapsed）
・The cascade temperature is -34 ° C or less, or even 15 minutes elapse
Number of revolutions at L side restart
> set temp.(SV)
+ Proportional band lower
limit (EL)
Constant speed control
H side ON
L side delay start
L side delay start period
(1 min or 8 min)
restart
L side restart defray period
(4 min~8 min)
≦set temp.(SV)
+ Proportional band
lower limit (EL)≧ set
temp.(SV)- Proportional
band upper limit (EH)
PID control
4000rpm (AT32℃ or more)
start initial period
Constant speed initial
period
Start initial period
(30sec ~ 120sec)
-26-
< set temp.(SV)
- Proportional band
upper limit (EH)
stop
Constant speed period