AME 10 Q4

Correct Answer: C) It opens the cooling valve while closing the heating valve.

Explanation:
If the jacket water temperature exceeds the setpoint, the controller increases its output signal to enter the upper range, which controls the cooling valve. The cooling valve opens to lower the temperature, and simultaneously, the heating valve is closed to prevent further heating.

Correct Answer: A) A single controller adjusts both heating and cooling valves, with the signal split into two ranges: one range controlling the heating valve and the other range controlling the cooling valve.

Explanation:

• In a split range control system, a single controller is used to manage both the heating and cooling processes. The controller's output signal is split into two distinct ranges.
• One range of the output signal operates the heating valve, while the other range operates the cooling valve.
• This approach ensures that as the jacket water temperature fluctuates, the controller can either increase heating (by opening the heating valve) or increase cooling (by opening the cooling valve), depending on the needs of the system.
• This method allows for smooth transitions between heating and cooling, maintaining the desired temperature setpoint.

Why the Other Options Are Incorrect:

B) Two separate controllers operate independently, one controlling the heating system and the other controlling the cooling system, with no interaction between them.

• This describes a dual control system, not a split range system. Split range control involves a single controller managing both heating and cooling, not two separate, independent controllers.

C) A primary controller adjusts the temperature setpoint, while a secondary controller modulates the flow of coolant based on the primary controller's output.

• This describes a cascade control system, where one controller (primary) sets the target for another (secondary). It does not describe a split range system, where one controller splits its output to control two different processes (heating and cooling).

D) A single controller controls the cooling valve, while a separate controller is responsible for monitoring temperature and making adjustments to the heating system.

• This again suggests independent control by separate controllers rather than a single controller splitting its output to manage both heating and cooling, which is the essence of a split range control system.

Correct Answer: B) The controller outputs a signal that is divided between heating and cooling operations.

Explanation:
The controller in a split range system outputs a single control signal that is divided across two operations—heating and cooling. The lower part of the signal range typically controls heating, and the upper part controls cooling, enabling smooth transitions between the two operations.

Correct Answer: A) The heating valve closes, and the cooling valve begins to open.

Explanation:
When the controller's output signal reaches the upper range, the system is responding to a condition where cooling is needed. The heating valve closes to stop any further heat input, and the cooling valve opens to bring the temperature down to the desired level.

Correct Answer: C) To provide a buffer zone where neither valve operates, allowing temperature stabilization.

Explanation:
A deadband or overlap in the control signal range provides a buffer zone where neither the heating nor cooling valve is operating. This allows the system to stabilize around the setpoint without oscillating between heating and cooling, leading to more stable temperature control.

Correct Answer: B) It provides smoother transitions between heating and cooling.

Explanation:
A split range control system offers smoother transitions between heating and cooling because both functions are managed by a single controller. This reduces the potential for conflicting operations and ensures a more stable temperature control, which is especially important in maintaining the engine's operational efficiency.

Correct Answer: C) When the jacket water temperature is above the setpoint.

Explanation:
When the jacket water temperature exceeds the setpoint, the split range control system responds by closing the heating valve to prevent further temperature rise. The cooling valve would then be opened to bring the temperature back down to the desired level.

Correct Answer: B) Pneumatic actuators

Explanation:
Pneumatic actuators are commonly used in marine control systems due to their reliability and ability to operate in harsh environments. They are also easily integrated with the control signals from a split range control system, providing smooth and accurate valve movement for both heating and cooling operations.