Question 426Electricity/Electronics - Assistant Engineer70% to pass
Suppose a cargo vessel of 1600 gross tons or more is fitted with emergency storage batteries for the purpose of supplying emergency lighting and power. According to 46 CFR, Subchapter J (Electrical Engineering), the capacity of the storage batteries is such that they should be able to successfully power the emergency loads for a period of 18 hours. Beginning with fully charged batteries, what is the minimum allowable voltage of the batteries after the 18 hour discharge period assuming a nominal voltage rating of 24 VDC and operating at rated capacity?
AI Explanation
The correct answer is C) 21.1 VDC.
According to 46 CFR Subchapter J, Section 111.15-10, emergency storage batteries for vessels of 1600 gross tons or more must be able to power the emergency loads for a minimum of 18 hours. Assuming a nominal voltage rating of 24 VDC, the minimum allowable voltage after the 18-hour discharge period is 21.1 VDC. This is because the batteries are expected to discharge to no less than 88% of their nominal voltage rating, which is 24 VDC x 0.88 = 21.1 VDC.
The other options are incorrect because 16.0 VDC is too low, 18.8 VDC is below the 88% threshold, and 22.8 VDC is above the minimum allowable voltage.
Related Questions
#424 According to 46 CFR, Subchapter J (Electrical Engineering), which of the following statements concerning battery installations is correct? #425 In accordance with 46 CFR Part 112, a storage battery for an emergency lighting and power system must have the capacity to accomplish which of the following? #427 While inspecting the copper commutator bars of a DC generator, you notice a chocolate brown film covering the bars. What should be done? #428 Incorrect brush pressure can result in accelerated brush wear on a DC generator. What statement concerning brush pressure is true? #429 As the brushes ride on the commutator of a DC generator, eventually mica ridges will form between the bars causing sparking and chipping of the brushes. When this happens the mica must be undercut. To what depth is the mica undercut?