Panasonic MDF-DU702VH, Service Manual

Page: 29 / 78

２．
Compressor normal mode
(1)
（
Speed control
）
Three type of comp. operation mode depending the chamber temp.
Chamber temperature > set temp.(SV)
+ Proportional band lower
limit (EL)
≦
set temp.(SV)
+ Proportional band
lower limit (EL)
≧
set
temp.(SV)- Proportional
band upper limit (EH)
< set temp.(SV)
- Proportional band
upper limit (EH)
Speed control Constant speed control PID control stop
(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
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
H side
H side ON
L side
L side restart
Constant speed period
L side delay start
restart
L side restart defray period
(4 min~8 min)
L side
L side delay start period
(1 min or 8 min)
Constant speed initial
period
start initial period
Start initial period
(30sec ~ 120sec)
4000rpm (AT32
℃
or more)
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