J&E Hall Cellar Plus 70-S1, Техническое руководство

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Issue: 01.07.2020 Page 19
Commissioning
Vacuum Operation
Do not operate scroll compressors in a vacuum condition, as this will cause the scrolls to overheat very quickly causing premature
failure.
Safety pressure switch settings
The Saginomiya DNS pressure switch fitted to the condensing units with auto reset for low pressure and manual reset for high
pressure is
NOT factory preset. BOTH THE LP AND HP SWITCH SETTINGS MUST BE ADJUSTED BEFORE STARTING THE UNIT. Be
sure that the high-pressure setting does not exceed the receiver’s maximum service pressure.
High pressure safety
The high-pressure safety switch is required to stop the compressor should the discharge pressure exceed the values shown in the
following table. The high-pressure switch can be set to lower values depending on the ambient conditions.
Low pressure safety
The low-pressure safety switch protects the compressor against deep vacuum operation, a potential cause of failure due to
internal arcing and overheating.
For ZB compressors, the low-pressure cut-out should be set as high as possible.
Care should be taken because the scroll sets will unload at a pressure ratio of approximately 10:1 for ZB compressors.
If the unit fails to pump down, the pump down pressure should be reset to a higher value.
Compressor operating pressures
The compressor operating pressures should be kept within the following limits:
Compressor
Refrigerant
S2/S3 Max. HP Set
Unit Series
ZB
R448A/R449A
27 bar
Compressor
Refrigerant
M in. Cut Out (barG)
M in. Cut Out (psi)
S2/S3
30
2
Unit Series
ZB
R448A/R449A
Compressor
Refrigerant
High Side (barG)
Low Side (barG)
7.1 ~ 27.7
S2/S3
2.0 ~ 7.1
Unit Series
ZB
R448A/R449A