GROL - General Radiotelephone Operator License Power Sources and Distribution Questions and Answers 1 — Questions and Answers
Question 1: A technician is servicing the power supply for a ship's primary HF transmitter. The technician observes that after the rectifier stage, the DC voltage has significant pulsating variations. Which component is most likely malfunctioning or missing?
- The step-down transformer
- The filter capacitor (Correct answer)
- The voltage regulator
- The power indicator LED
Correct answer: The filter capacitor
The rectifier converts AC to pulsating DC. The filter capacitor's job is to smooth out these pulsations by storing energy during voltage peaks and releasing it during troughs, creating a more stable DC voltage. Significant ripple indicates a faulty or failed filter capacitor.
Question 2: Under GMDSS regulations, a ship is equipped with an emergency generator. What is the minimum duration that the reserve source of energy (typically batteries) must be able to power the essential radio equipment?
- 30 minutes
- 6 hours
- 3 hours
- 1 hour (Correct answer)
Correct answer: 1 hour
According to SOLAS Chapter IV, Regulation 13, if a ship is provided with an emergency source of electrical power (like an emergency generator) that can power the radio equipment, the reserve source of energy must be able to power the installation for at least 1 hour. If there is no emergency generator, the requirement is 6 hours.
Question 3: When performing routine maintenance on a bank of flooded lead-acid batteries used as a reserve power source, what is the correct fluid to add if the electrolyte level is low?
- Sulfuric acid
- Tap water
- Distilled water (Correct answer)
- Saltwater solution
Correct answer: Distilled water
When a lead-acid battery is charged and discharged, only water is lost through gassing and evaporation; the acid remains. To restore the proper electrolyte level, only distilled or deionized water should be added. Adding acid will increase the specific gravity to an incorrect level and can damage the battery plates. Tap water contains minerals that can coat the plates and reduce battery capacity.
Question 4: In a marine radio installation's DC power supply, what is the primary function of the voltage regulator circuit?
- To convert the ship's AC power to DC power.
- To increase the amperage available to the transmitter.
- To maintain a constant output voltage despite fluctuations in input voltage or load. (Correct answer)
- To filter out RF noise from the DC power lines.
Correct answer: To maintain a constant output voltage despite fluctuations in input voltage or load.
A voltage regulator's specific purpose is to maintain a fixed output voltage, protecting sensitive electronic equipment from variations in the power source (like a charging alternator) or changes in the current draw from the load (like keying the transmitter). Rectifiers convert AC to DC, and filters (capacitors/inductors) remove noise.
Question 5: A vessel's GMDSS console is powered by a 24V battery bank as its reserve source of energy. During a capacity test, the technician must monitor the voltage to avoid a deep discharge. For a typical nickel-based battery pack, discharging a cell below what voltage level can cause irreversible damage?
- 1.5V per cell
- 0.5V per cell
- 1.0V per cell (Correct answer)
- 1.2V per cell
Correct answer: 1.0V per cell
Deep discharging a battery can cause permanent damage and loss of capacity. For nickel-based battery systems (like NiCd or NiMH) often used in these applications, the minimum safe voltage level is considered to be 1.0V per cell. Discharging below this point can lead to cell reversal and permanent failure.
Question 6: Which of the following is an essential and routine maintenance practice for ensuring the reliability of terminal connections on a lead-acid battery bank used for emergency power?
- Painting the terminals with marine-grade paint to prevent water intrusion.
- Applying a solution of baking soda and water to clean away corrosion. (Correct answer)
- Frequently spraying the terminals with saltwater to improve conductivity.
- Leaving terminal connections slightly loose to allow for thermal expansion.
Correct answer: Applying a solution of baking soda and water to clean away corrosion.
Corrosion on battery terminals increases resistance, which can hinder current flow and prevent proper charging or power delivery. A solution of baking soda and water effectively neutralizes the acidic corrosion (lead sulfate). After cleaning, the terminals should be rinsed, dried, and coated with a protective spray or petroleum jelly.
GROL - General Radiotelephone Operator License Power Sources and Distribution Questions and Answers 1
A technician is servicing the power supply for a ship's primary HF transmitter.
The technician observes that after the rectifier stage, the DC voltage has significant pulsating variations.
Which component is most likely malfunctioning or missing?