On a modern refrigerated container unit employing suction modulation for the purposes of capacity control and capacity limitation, what happens when the applied voltage and current draw associated with the normally open (NO) suction modulation valve located in the suction line both increase?
Official USCG Answer & Rule Citation
Correct Answer: Option B — the valve will further close, raising evaporator pressure and lowering suction pressure
Increasing current to a normally open suction modulation valve drives it further closed, restricting suction gas flow, which lowers downstream evaporator pressure while raising compressor suction pressure.
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