Certified Data Centre Professional (CDCP) Practice Exam

The correct term that describes the voltage difference between ground and neutral is common mode noise. This phenomenon primarily occurs in electrical systems where there is an unintended voltage present on the neutral conductor relative to the ground. Common mode noise can result from a variety of sources, including stray currents, electromagnetic interference, or unbalanced loads on the electrical system.

Understanding common mode noise is crucial for data centers and other facilities that require stable and reliable power. Excessive common mode noise can affect the performance of sensitive electronic equipment, leading to issues such as data corruption or equipment malfunction.

In contrast, the other terms do not accurately define the relationship between ground and neutral. Phase shift refers to the difference in phase angle between two alternating current signals and doesn't relate to voltage differences. Harmonic distortion involves the presence of frequencies that are multiples of the fundamental frequency and can affect power quality but is not a direct measure of ground-neutral voltage difference. Electrical imbalance refers to an uneven distribution of current in a three-phase electrical system but does not specifically indicate the voltage difference between ground and neutral.