Rectifier Practice Questions

These questions test impressed current CP rectifier operation, inspection, output interpretation, and troubleshooting.

Study Focus

Focus on polarity, DC output, voltage and current trends, anode circuits, structure returns, interruption, RMU verification, and why output alone does not prove protection.

Practice Questions

  1. In an impressed current CP rectifier, the positive terminal is normally connected to:

    1. The protected structure
    2. The reference electrode
    3. The anode system
    4. The coating holiday

    Answer: C. The positive terminal is normally connected to the impressed current anode system.

  2. The negative rectifier terminal is normally connected to:

    1. The protected structure
    2. The anode backfill only
    3. The reference electrode cap
    4. The AC ground only

    Answer: A. The negative terminal is normally connected to the protected structure.

  3. Why is reversed rectifier polarity dangerous?

    1. It can make the protected structure discharge current and corrode rapidly
    2. It improves all coating systems
    3. It makes all readings native
    4. It eliminates all interference

    Answer: A. Reversed polarity can cause severe corrosion of the intended protected structure.

  4. A rectifier operates at 60 volts and 2 amps. What is the effective circuit resistance?

    1. 30 ohms
    2. 120 ohms
    3. 0.033 ohms
    4. 62 ohms

    Answer: A. R = V ÷ I = 60 ÷ 2 = 30 ohms.

  5. High rectifier voltage with low current may indicate:

    1. A high-resistance or open circuit
    2. A perfect coating survey
    3. No electrolyte anywhere
    4. Guaranteed overprotection at every point

    Answer: A. High voltage with low current often suggests increased circuit resistance.

  6. Why should rectifier output be compared with historical data?

    1. Trends can reveal developing system problems
    2. Historical data is never useful
    3. Voltage and current do not change
    4. Only nameplate data matters

    Answer: A. Changes in output trends may indicate circuit, groundbed, coating, or continuity changes.

  7. Why does rectifier output alone not prove adequate protection?

    1. It does not prove current distribution or structure polarization at all required locations
    2. It proves no current exists
    3. It only applies to galvanic anodes
    4. It replaces reference electrodes

    Answer: A. Output must be interpreted with structure measurements and current distribution.

  8. What is one reason to verify RMU readings with a portable meter?

    1. RMU data may be stale, scaled incorrectly, or sensor-based
    2. RMUs always report pipe diameter
    3. Portable meters cannot measure voltage
    4. RMUs eliminate all testing requirements

    Answer: A. RMU values should be validated when accuracy matters.

  9. What does zero rectifier output potentially indicate?

    1. Power loss, blown fuse, failed component, intentional shutdown, or open circuit
    2. Automatic proof of abandonment
    3. Guaranteed protection
    4. Only reference electrode failure

    Answer: A. Zero output has multiple possible causes and requires diagnosis.

  10. What should be checked before increasing rectifier output?

    1. Structure potentials, current distribution, interference risk, and system condition
    2. Only the cabinet paint color
    3. Nothing; more output is always better
    4. Only the weather forecast

    Answer: A. Output adjustment should be based on system response and risk.

Related Study Pages