Plant Operator Selection System Test POSS 3

Question 1

A log table shows turbine vibration readings for Monday through Friday: 2.1, 2.4, 2.0, 2.8, 3.1 mils. What is the average vibration for the week?

Accepted Answer

2.48 mils

Answer

(2.1 + 2.4 + 2.0 + 2.8 + 3.1) ÷ 5 = 12.4 ÷ 5 = 2.48 mils.

Question 2

Which mechanical principle explains why a longer wrench handle makes it easier to loosen a bolt?

Accepted Answer

Mechanical advantage through leverage

Answer

A longer handle increases the moment arm, providing greater torque (leverage) with the same applied force.

Question 3

A plant procedure states: 'Isolate the equipment, verify zero energy state, then apply lockout/tagout.' Which step comes second?

Accepted Answer

Verify zero energy state

Answer

The passage specifies the order: isolate first, verify zero energy second, then apply lockout/tagout.

Question 4

A pipe carries steam at 150 psi. The pipe diameter is reduced by half. What happens to the steam velocity?

Accepted Answer

It quadruples

Answer

Halving the diameter reduces cross-sectional area by 75% (area ∝ r²), so velocity increases 4× to maintain flow continuity.

Question 5

A chart shows that Motor 3 consumes 18 kW at full load and 6 kW at no load. What percentage of full-load power is the no-load consumption?

Accepted Answer

33%

Answer

6 kW ÷ 18 kW = 0.333 = 33.3%, so no-load is approximately 33% of full-load power.

Plant Operator Selection System Test Practice Test