2.11 System Charge Limit
The proper system charge can keep the system parameters in the normal level, such as cooling and heating
capacity, sub cooling degree, suction and discharge temperature, compressor's sump temperature, etc.
The refrigerant charge and refrigerant oil in the system should keep the ratio as follow:
Note: Specific gravity of the Oil using in R407C/R410A/R134a series compressors is 0.94
If oil/refrigerant ratio is lower than 0.35, it will cause dilution of oil and lack of lubrication inside of compressor.
So please inform us before the system being tested under 0.35>oil(kg)/refrigerant (kg) ≥0.3 condition,
some detailed advices will be given about oil level in compressor .
As a general requirement, oil (kg)/refrigerant (kg) >0.3 shall be kept.
2.12 Oil level of the compressor
The minimum oil level in the compressor shall comply with the requirements of the compressor specification
to ensure the compressor reliability. When the oil is foamed, do not consider the foaming portion as oil level.
Low oil level will cause lack of lubrication to rotating parts and seriously affect the compressor reliability.
Observe the oil level with the compressor with sight glass supplied by Panasonic, and consult your account
representative for the result.
<<Example showed the oil level to keep>>
· level A : the lowest oil level during transition
operation; (Distance to the Bottom 10mm)
· level B : the lowest oil level during stable
operation; (Distance to the Bottom 38mm)
· level C : the highest oil level during stable
operation; (Distance to the Top 15mm)
2.13 Operating Envelope
The operating envelopes of inverter compressors depend on the running speed. The envelope limitations are
varied for different speed range, which are defined by mainly considering the limits of discharge temperature,
compression ratio, lubrication and power limitation.
The operation of compressor shall be under the Operation Envelope that described in the compressor
specification at all conditions. However, when operating conditions exceed the range described in the
specification during transitional period such as during start up and defrosting, it may be judged by testing or
checking the operating data.
Oil (kg)/ Refrigerant (kg)≥0.35