Multi-compressor system with normally-open valves in oil balancing connections

A multi-compressor system comprising:

• a plurality of compressors which are parallelly coupled, the plurality of compressors comprising at least two compressors, each compressor including a compressor shell provided with a refrigerant suction fitting, a refrigerant discharge fitting and an oil balancing connection, each oil balancing connection being fluidly connected to a low pressure volume of the respective compressor,
• a common suction line and inlet connection lines each connecting the common suction line to the refrigerant suction fitting of a respective compressor,
• a common discharge line and outlet connection lines each connecting the common discharge line to the refrigerant discharge fitting of a respective compressor,
• a common oil balancing line and balancing connection lines each connecting the common oil balancing line to the oil balancing connection of a respective compressor, and
• a plurality of spring-loaded normally-open valves each associated with a respective compressor, each spring-loaded normally-open valve being configured to occupy an open configuration in which said spring-loaded normally-open valve fluidly connects the low pressure volume of the respective compressor with the common oil balancing line and a closed configuration in which said spring-loaded normally-open valve at least partially fluidly isolates the low pressure volume of the respective compressor from the common oil balancing line, each spring-loaded normally-open valve being configured to be displaced in the closed configuration when a pressure difference between a pressure prevailing in the low pressure volume of the respective compressor and a pressure prevailing in the common oil balancing line reaches a predetermined value.