As shown in the illustrated alternator...

Question 1 / 205eccefa4bacbc34ba4d48465

Question 1 of 205eccefa4bacbc34ba4d48465

As shown in the illustrated alternator protection scheme diagram, what function does the negative phase sequence relay (NPS) perform? See illustration EL-0067.

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Question 1 of 20

5eccefa4bacbc34ba4d48465

As shown in the illustrated alternator protection scheme diagram, what function does the negative phase sequence relay (NPS) perform? See illustration EL-0067.

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🔍 Key Concepts

• Negative phase sequence (NPS) currents and what typically causes them in a 3‑phase alternator • Difference between short‑circuit overcurrent protection and unbalanced current protection • How time‑delay overload relays usually relate trip time to the size of the overload current

💭 Think About

• Look at where the block labeled "OCIT OC (inst) NPS" is connected in the diagram. What are the current transformers (CTs) measuring there: total current magnitude, or the balance between the three phase currents? • Which of the options describes a condition that would exist even if all three phase currents were equal, and which option describes a condition where one or more phase currents differ from the others? • Think about what negative phase‑sequence currents physically do to the rotor of an alternator. Does that relate more to general overload, to a high fault current, or to unbalanced stator currents?

✅ Before You Answer

• Identify which choice mentions unbalanced phase or stator currents – this is closely related to negative phase‑sequence conditions. • Separate functions: which protection would be handled by an instantaneous overcurrent relay versus a specialized NPS relay? • Verify which answers talk about time‑delay overload (trip time vs. current) – that is usually handled by thermal or inverse‑time overcurrent relays, not NPS.

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Question 1 of 20

As shown in the illustrated alternator protection scheme diagram, what function does the negative phase sequence relay (NPS) perform? See illustration EL-0067.

trips the alternator circuit breaker due to extremely high over current caused by a short-circuit fault

trips the alternator circuit breaker due to sustained motor overload current where the trip delay is directly proportional to the overload current

trips the alternator circuit breaker due to sustained motor overload current where the trip delay is inversely proportional to the overload current

trips the alternator circuit breaker in the event of unbalanced stator currents

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Question 1 / 205eccefa4bacbc34ba4d48465

Question 1 of 205eccefa4bacbc34ba4d48465

As shown in the illustrated alternator protection scheme diagram, what function does the negative phase sequence relay (NPS) perform? See illustration EL-0067.

Back

Question 1 of 20

5eccefa4bacbc34ba4d48465

As shown in the illustrated alternator protection scheme diagram, what function does the negative phase sequence relay (NPS) perform? See illustration EL-0067.

No comments yet

Be the first to share your thoughts!

If the question has a related picture, it will appear here.

🔍 Key Concepts

💭 Think About

✅ Before You Answer

👋 Hi! I'm Genie, your AI study assistant. How can I help you with this question?

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