Free sample: 2 of 45
Answer each one before you open the explanation. On the exam there's no explanation, and you have about 77 seconds a question on RC and BT, 90 on TO and BI.
The per unit voltages in the PRC-024-3 Attachment 2 no trip boundaries are referred to one particular measurement location. Which location is it?
- A. The generator terminals, on the machine side of the breaker
- B. The low side of the generator step-up transformer
- C. The unit auxiliary transformer secondary bus
- D. The high side of the generator step-up transformer
Show the answer
Answer D The high side of the generator step-up transformer
Attachment 2 states that its voltage values are at the high side of the generator step-up transformer or main power transformer, with the per unit base being the nominal transmission system voltage unless the Transmission Planner specifies otherwise. Where protection actually measures voltage elsewhere, the setting has to be evaluated back to that high-side reference.
Reference: PRC-024-3 R2; Attachment 2
In the Eastern Interconnection, within which frequency band does the PRC-024-3 Attachment 1 no trip zone call for continuous operation rather than a minimum ride-through time?
- A. Above 59.5 Hz and below 60.5 Hz
- B. Above 59.4 Hz and below 60.6 Hz
- C. Above 58.4 Hz and below 61.6 Hz
- D. Above 57.8 Hz and below 61.8 Hz
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Answer A Above 59.5 Hz and below 60.5 Hz
The Eastern Interconnection table shows continuous operation above 59.5 Hz and below 60.5 Hz; beyond that band the no trip zone is bounded by a minimum time that shortens as frequency moves further from 60 Hz, ending in an instantaneous allowance at 61.8 Hz and at 57.8 Hz. The wider 59.4 Hz to 60.6 Hz continuous band belongs to the Western, Quebec and ERCOT tables, not to the Eastern one.
Reference: PRC-024-3 R1; Attachment 1, Table 1
