What is HCT and LLOP? Why is a DG set to stop automatically by PMU under HCT and LLOP alarms on cellular towers? What do these alarms indicate?

LLOP - Low Lub Oil Pressure - If Lub oil pressure if less than LLOP setting then the Dg set will get tripped to protect the engine.

HCT - High cylinder Temperature - If the engine cylinder temperature while operating, is more than HCT setting then the Dg set will get tripped to protect the engine.

These are the protections provided on the diesel engine to avoid severe damage in case of abnormality.

LLOP indicates that the lub oil flow is restricted due to problem in lub oil pump or some blockage in the lub oil pipeline or leakage etc.

HCT may be due to some of the problems in engine as below:

a. Increase in Engine Load

b. Fuel Valve/Supply

c. Exhaust Valve Passing

d. Fouling of Exhaust Gas Passageways

e. Fouling of the Scavenge Air Passageways

f. Leakage of the Scavenge Air.

g. Scavenge Fire

h. Insufficient /Unsatisfactory HFO Treatment.

i. Insufficient Air Supply to Blower

j.  exhaust Valve Timing Problem