Class 2 (2nd Engineer) MEKG 📅 Apr 2019

Exam Question

With Reference to Air conditioning System onboard your vessel

(a) Sketch and describe a high pressure cut out in a refrigeration system.

(b) The refrigeration compressor has stopped due to operation of the h.p. cutout, explain

(i) The possible causes.

(ii) How these causes would be found and possible remedies

Reference Answer

(a) A high-pressure cut-out in a refrigeration system is a safety device that protects the system from operating at dangerously high pressures. It consists of a bellows connected to the compressor discharge, a spring, an adjustment screw, and a switch arm. Under normal conditions, the switch arm is held up, maintaining electrical contact. When pressure exceeds the set limit, the bellows expands, releasing the switch arm, and the compressor cuts out, preventing further damage. The cut-out needs manual reset after troubleshooting and pressure returns to safe levels. It ensures system safety and prevents over-pressurization risks.
(b) (i) The possible cause of HP cut out could be due to:
Dirty condenser
Overcharge of refrigerant

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