AUTO 1 MIDTERM QUIZ NO. 2 PART 1

The main engine's jacket water outlet temperature needs precise control. The seawater temperature, which cools the jacket water, often fluctuates. How would you apply a cascade control system to maintain a stable jacket water temperature?

• The primary loop controls jacket water outlet temperature; the secondary loop controls the 3-way valve position.

• The primary loop controls cooling seawater flow; the secondary loop controls jacket water outlet temperature.

• The primary loop controls the engine load; the secondary loop controls the jacket water pump speed.

• The primary loop controls seawater cooling temperature; the secondary loop controls the main engine RPM.

On a vessel with a steam boiler, the drum water level must be kept extremely stable. The feedwater supply pressure, however, is known to fluctuate. What is the best cascade control strategy to ensure a stable drum level?

• The primary controller manages the boiler firing rate; the secondary controller manages the steam flow rate.

• The primary controller manages the steam pressure; the secondary controller manages the drum water level.

• The primary controller manages the feedwater flow rate; the secondary controller manages the drum level.

• The primary controller manages the drum level; the secondary controller manages the feedwater flow rate.

A ship's fuel oil viscosity controller must deliver fuel at a constant viscosity to the main engine. This is done by heating the fuel. The steam pressure to the heater often varies. How should a cascade system be configured?

• The primary controller manages the fuel viscosity; the secondary controller manages the steam pressure to the heater.

• The primary controller manages the steam pressure; the secondary controller manages the fuel viscosity.

• Both controllers manage the fuel viscosity equally.

• The system does not require a cascade configuration.

The primary loop controls fuel oil temperature; the secondary loop controls the final fuel oil viscosity.

• The primary loop controls fuel oil temperature; the secondary loop controls the final fuel oil viscosity.

• The primary loop controls fuel oil viscosity; the secondary loop controls the fuel transfer pump pressure.

• The primary loop controls the steam pressure; the secondary loop controls the fuel flow rate.

• The primary loop controls fuel oil viscosity; the secondary loop controls the fuel's temperature in the heater.

In a main engine lubricating oil temperature control system, the secondary (slave) controller is put into 'manual' mode by an engineer. What is the immediate consequence for the control system's operation?

• The primary controller's output now directly controls the 3-way valve, maintaining full automatic control.

• The entire lubrication oil system will automatically shut down as a safety precaution.

• The 3-way valve position is now fixed, and the primary controller can no longer regulate the oil temperature.

• The secondary controller will begin to function as a simple on-off switch for the 3-way valve.

Heating steam supply pressure fluctuates. How would cascade control be applied here?

• The primary loop controls the seawater temperature; the secondary loop controls the ejector pump speed.

• The primary loop controls the shell pressure; the secondary loop controls the steam flow to the heater.

• The primary loop controls the final water salinity; the secondary loop controls the shell pressure.

• The primary loop controls the steam flow; the secondary loop controls the final freshwater output.

For a cascade control system on a ship to function correctly and be stable, a fundamental timing relationship must exist between the two loops. Which of the following describes this essential relationship?

• The primary (master) loop must be tuned to react much faster than the secondary (slave) loop.

• Both the primary and secondary loops must be tuned to react at the exact same speed for synchronization.

• The reaction speed of the loops is not important as long as the final control element is correctly sized.

• The secondary (slave) loop must be tuned to react much faster than the primary (master) loop.

The steam pressure in the main line for deck machinery like mooring winches needs to be stable, but the load changes drastically when a winch starts or stops. How would a cascade system on the boiler be applied to handle this?

• The primary loop controls winch speed; the secondary loop controls the main steam line pressure.

• The primary loop controls fuel oil flow; the secondary loop controls the steam line pressure.

• The primary loop controls the steam line pressure; the secondary loop controls the boiler's fuel oil flow.

• The primary loop controls the drum level; the secondary loop controls the boiler's fuel oil flow.

A controllable pitch propeller (CPP) system's oil pressure must be maintained. The primary controller manages the system pressure. A secondary controller is added to manage the speed of the electric hydraulic pump. When is this cascade arrangement most useful?

• When the captain gives frequent and rapid pitch change commands from the bridge.

• When the oil filter in the hydraulic system becomes clogged over a period of many weeks.

• When the temperature of the hydraulic oil changes due to prolonged maneuvering operations.

• When the ship's main electrical voltage supply fluctuates, affecting the pump motor's speed.

You are designing a cascade system to control the temperature of heavy fuel oil being supplied to a diesel generator. The final control element is a steam valve. Which of the following represents the most significant disturbance that the secondary loop would be responsible for rejecting?

• Change in ambient temperature

• Change in fuel oil viscosity

• Change in steam pressure supplied to the heat exchanger

• Change in generator load