Mitsubishi Electric PKA-RP1.6GAL Service Technical Manual page 50

Control modes
4-1. Normal control
4. LEV(B)
4-2. Evaporation protection control
4-3. Low discharge super heat temperature protection control
4-4. Others
5-1. Normal control
5. Four way valve
5-2. Change of Operation mode
LEV opening pulse will be controlled according to the change of compressor
operating frequency and regulated every minute to adjust the discharge
temperature to let the intake super heat temperature be 0: to 5:.
• Control timing: Once per minute after 3 or 7 minutes have passed since the
compressor started.
• Opening pulse range: The following range is specified according to the
compressor operating frequency.
Opening pulse range (Lower limit to upper limit)
Compressor
frequency PUHZ-RP1.6, 2VHA
49Hz or less 65 ~ 250
50Hz to 75Hz 95 ~ 350
76Hz to 90Hz 120 ~ 400
91Hz to more 140 ~ 480
• Opening pulse range corresponding to the change of compressor operating
frequency
Opening pulse range = Present opening pulse O (Target frequency / Operating
frequency -1) O 0.8
• Compressor start-up
Opening pulse will be adjusted according to only the change of frequency
during 3 or 7 minute start-up. The start-up control time will be changed
according to the discharge temperature (TH4).
Discharge temperature (TH4) ] 30:: 3 minute start-up
Discharge temperature (TH4) < 30:: 7 minute start-up
The targeted opening pulse should be made large in the condition written below.
Indoor cond./eva. temperature (TH5) - Indoor liquid pipe temperature (TH2) ] 6:
Set the targeted value of the discharge temperature about 5 to 15: lower.
W This control does not work for 3 or 7 minutes after the compressor gets started.
Set a small value for the targeted opening pulse according to the discharge
super heat temperature.
• Correction range of the discharge super heat temp. : 10: or less
W This control does not work for 3 or 7 minutes after the compressor gets started.
1 LEV opening pulse is set to 400 while the compressor is being stopped.
2 After LEV opening pulse is initialized to 0 by making 700 pulse down from
the present pulse, set the pulse to 400.
3 20 pulses are added to the present pulse if the following conditions are
satisfied within 14 minutes after the compressor gets started.
COOL: Indoor cond./eva. temperature (TH5) - Indoor liquid pipe temperature (TH2) ] 25:
HEAT: Outdoor cond./eva. temperature (TH6) - Outdoor liquid pipe temperature (TH3) ] 25:
Always OFF during normal operation.
When the mode changes from HEAT to COOL:
COOL
Operation mode
HEAT
ON
Four way valve
OFF
Control details
PUHZ-RP2.5, 3VHA PUHZ-RP4,5,6VHA
70 ~ 250
105 ~ 350
160 ~ 400
160 ~ 480
50
Remarks
80 ~ 300
90 ~ 350
100 ~ 400
120 ~ 480
Discharge super
heat temp. is
calculated from
discharge temp.
(TH4) and
outdoor
cond./eva. temp.
(TH6).