In a cascade system, adding a second compressor mainly helps to prevent what?

• A. Very high compression ratio for each compressor
• B. Overcooling the product
• C. Overloading the power supply
• D. Increased refrigerant leakage

Answer: (A)

In a cascade system, the total pressure rise required is split between two compressors, so each one only has to achieve a moderate compression ratio. This prevents any single compressor from needing a very high per-stage ratio. With lower ratios per compressor, discharge temperatures stay lower, efficiency improves, and mechanical stress is reduced. The two-stage arrangement also lets you match each stage to an appropriate refrigerant for its temperature range. So the main benefit of adding a second compressor is to prevent very high compression ratios for each compressor.

The other issues listed aren’t the primary reason for cascading; they can be concerns in some designs, but the key advantage here is distributing the compression requirement across stages.