Version 2.02 15.05.2007 Function of VS 3000
46
3.36.7 Sequence of Z2 discharge gas defrosting with coldroom defrost mode set
to El. With UA 300
Signal: Start delayfor
drain heater5
to 30 minfor
oil equaliz-
ation
Unload to
one stage
Speed =
Minimum
Pumpdown
to suction
pressure at
LP Low
Defrost time
10 to 30 min.
Defrost termination
1 Drain heater Z2 coldrooms No start delay if power failure oc-
curs during defrosting and in sep-
arate defrost
2 SV2.2/1 close suction line 4 min monitoring time for pump-
down. SV opens 10 to 100 sec
after SV3.2. Z2 Low LP alarm dis-
abled.
3 SV1 common discharge
line
SV3.2/1, SV3.2/2 discharge feed
closed 5 s ec later
4 SV3.2/1discharge gas feed Z2 coldrooms disabled with elec-
tric defrost. Defrost termination by
temperature or defrost duration on
NT cases.
5 Defrost command to Z2
cases (not to Z2 coldrooms)
via bus
6 Disable Z2 coldrooms
7 Disable all Z2 refrigeration
points via bus
Start on defrost termination. End
30 sec after first Z2 compressor
starts. Max. 5 min duration
8 Setpoint toggle Z1 pack (no
shift)
AL 300/CI 3000 displays A before
t0 setpoint in overview
9 Forced cooling of all Z1 re-
frigeration points via bus
10 Disable LP Measuring Loop
Error alarm
5 min after opening suction line
11 Disable Z2 refrigeration
points 1.5 min before open-
ing suction line when de-
frost duration equal to max.
defrost time
Absaugen
oder Verd.
sperre
Without oil equalizer:
Enable compressors when
t0_Z2 < t0_Enable
With oil
equalizer:
Enable compressors when
t0_Z2 < (t0_Z1 + 2K)
Max. disable after defrost 5 min.
Min. disable 10 sec
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