Governor Flashcards
What is the primary function of a governor in rotating equipment?
To maintain the integrity and safety of rotating equipment by sensing and controlling the machine’s speed during operation.
Why must an overspeed shutdown safety device be installed on a governor system?
To protect against runaway conditions that could cause damage to the prime mover and driven machine or result in catastrophic failure.
What adjustment is recommended for a new governor during installation?
Manually decrease the governor speed setting screw so that the initial start-up speed is lower than required.
What is commonly done on engines to prevent damage during an overspeed situation?
The air inlet to the intake manifold is shut off to stop the engine.
What are the key maintenance tasks for a governor system?
Lubricate all linkages and pivot points, replace worn parts, check and adjust clearances, inspect the throttle valve, and clean the trip valve.
What is an indication that dirt or sludge is present in the housing of a governor?
The presence of dirt or sludge indicates that the governor needs to be dismantled, cleaned, and inspected.
When should a governor system be overhauled?
Whenever there is contamination in the hydraulic system or during a major overhaul of the engine or turbine.
What are some signs that indicate the need for an oil change in a governor system?
Changes in oil appearance, burnt smell, traces of moisture, changes in viscosity, or excessively worn parts.
What precautions should be taken during the overhaul of a governor system?
Replace all seals and gaskets, check linkages for stiffness, clean lines and passages, and flush the system with the correct hydraulic oil.
Why is oil maintenance critical in a hydraulic governor system?
To prevent contamination and damage to sensitive components, ensure smooth operation, and avoid catastrophic system failure.
What are the routine maintenance tasks for a mechanical governor?
Ensure knife edges and pivot points are in good condition, sliding parts are not binding, and anti-friction bearings are free of wear.
What is a critical danger associated with governor system malfunctions?
It can result in catastrophic system failure or loss of life to operating and maintenance personnel.
What is the primary function of a governor in a prime mover?
To automatically control the speed of the prime mover under varying load conditions.
List three key actions performed by a governor on a prime mover.
Maintain the selected speed.
Limit slow and fast speeds.
Shut down the prime mover if it overspeeds.
What are the two independent systems used for controlling the speed of steam turbines?
The operating speed control or governor to actuate the steam valves.
The overspeed control system to protect the turbine from destruction in case of an overspeed situation.
Why is it necessary to manually decrease the governor speed setting screw when placing a new governor into service?
To ensure the speed is lower than required at initial start-up.
What must be equipped in a prime mover to prevent catastrophic failure or damage?
An overspeed shutdown safety device.
What happens during overspeed in engines, and how is it commonly mitigated?
The air inlet to the intake manifold is shut off to prevent further acceleration.
What routine preventative maintenance tasks are essential for governors?
Lubricate all linkages and pivot points.
Replace worn parts.
Check governor clearances and adjustments using manufacturer specifications.
Inspect and clean the trip valve and governor throttle valve.
What are the primary causes of governor system malfunctions?
Incorrect speed setting.
Improper steam pressure (steam turbines) or fuel delivery (stationary engines or gas turbines).
Manual overrides or control valves blocking fuel or steam delivery.
What steps are required during a major overhaul of a governor system?
Replace all seals and gaskets.
Check and ensure mechanical tolerances match original specifications.
Flush parts with the correct hydraulic oil.
What are the three components common to all automatic governor systems?
Detection.
Transmission.
Correction.
Explain how a mechanical-hydraulic governor works.
It uses hydraulic pressure to actuate a spool valve that controls the steam valve to adjust speed.
What are the most common types of throttle valve governors?
Automatic or vacuum governors and centrifugal governors.
In a vacuum governor, how is engine speed monitored and adjusted?
Engine vacuum causes a diaphragm to move, adjusting the throttle valve to regulate air-fuel mixture and maintain speed.
What does a governor’s control rack do in a diesel engine?
Adjusts the amount of fuel injected into the cylinders, increasing or decreasing speed as required.
Why is oil maintenance critical in hydraulic governor systems?
To prevent contamination, wear, and ensure smooth operation over extended periods.
What are the primary functions of a governor on steam turbines?
The governor regulates operating speed by controlling steam valves to speed up or slow down the turbine and prevents overspeeding to protect against mechanical damage.
What is the purpose of overspeed control systems in turbines?
Overspeed control systems protect the turbine from destruction in the event of overspeed situations.
What do governors automatically control in stationary engines?
Governors automatically control the speed of a prime mover under varying load conditions by maintaining selected speed, limiting fast speeds, and shutting down the prime mover if it overspeeds.
What are the three essential components common to all automatic governor control systems?
Detection, transmission, and correction.
How do isochronous governors differ from variable speed governors?
Isochronous governors maintain a uniform, constant speed without fluctuation, while variable speed governors allow adjustment of speed within a range.
What is the function of a pressure-regulating governor?
Pressure-regulating governors maintain constant pipeline pressure by throttling the pump as needed.
How does an electric load-sensing governor operate?
It detects changes in load and adjusts the fuel supply to maintain stable frequency and speed in electric power generation plants.
What parameters must be monitored for gas turbine governors?
Parameters include actuator position, turbine rpm, compressor inlet air temperature and pressure, and combustor discharge pressure.
How does a vacuum governor regulate engine speed?
A vacuum governor uses intake manifold vacuum to adjust throttle valve position, controlling the air-fuel mixture.
Why is an increase in fuel burned important for a gas turbine?
It produces more heat, enabling the turbine to carry a larger load.
What is the primary purpose of speed-limiting governors?
Speed-limiting governors prevent overspeeding but do not shut down the unit. Instead, they limit it to a maximum speed.
What controls a diesel engine’s governor system?
The governor system adjusts fuel delivery by controlling a linkage connected to a control rack that modifies the plunger’s position in the cylinders.
How does a pressure-regulating governor adjust pump speed?
It senses pressure through bellows or a diaphragm, which moves the control rod to adjust the pump’s throttle.
What is the purpose of a governor in rotating equipment?
A governor maintains the integrity and safety of the rotating equipment by sensing and controlling its speed during operation.
Why is an overspeed shutdown safety device essential for prime movers?
It protects against runaway conditions that can damage the prime mover or driven machine and potentially cause catastrophic failure.
What adjustments are typically made when placing a new governor into service?
The speed setting screw is manually decreased to ensure the speed is lower than required during the initial startup.
What should be done to the air intake on engines during an overspeed situation?
The air intake manifold should be shut off to prevent damage.
List three routine preventative maintenance steps for governors.
Lubricate all linkages and pivot points, replace worn parts, and check clearances using manufacturer specifications.
What is the primary cause of hunting in governors?
Hunting occurs when the governor reacts too quickly to speed changes, resulting in repeated over-correction.
Define speed droop in governors.
Speed droop is the percentage decrease in speed required by the governor to provide an increase in throttle during load changes.
What are the primary components of a flyweight governor?
Flyweights, speeder spring, rotating ballhead, and control rod.
What is the role of centrifugal force in a flyweight governor?
Centrifugal force moves the flyweights outward, adjusting the control rod to maintain engine speed.
Why is complete reduction of friction in a flyweight governor undesirable?
It could result in oscillation of the speed adjustment, requiring further corrections.
What is the main purpose of the governor rod in steam turbines?
To adjust the steam valve based on the speed of the turbine.
What happens when a steam turbine experiences overspeed?
The governor shuts the steam valve, reducing the flow and slowing the turbine.
What is the main function of isochronous control governors?
To maintain a uniform and constant speed without fluctuation.
Where are electric load-sensing governors typically used?
In power plants, where maintaining a stable frequency is critical.
How does a variable speed governor differ from an isochronous governor?
It allows adjustment to maintain any selected speed, not just constant speed.
What causes pressure-regulating governors to adjust the pump speed?
Changes in fluid pressure.