Electrical Wiring Residential
19th Edition
ISBN: 9781337101837
Author: Ray C. Mullin, Phil Simmons
Publisher: Cengage Learning
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Textbook Question
Chapter 28, Problem 15R
The utility company has provided a letter to the contractor stating that the available fault current at the line side of the main service-entrance equipment in a residence is 17,000 amperes RMS symmetrical, line to line. In the space following each statement, write in “Meets Code” or “Violation” of 110.9 and 110.10 of the Code.
- a. Main breaker has a 10,000-ampere interrupting rating; branch breakers have a 10,000-ampere interrupting rating. _______
- b. Main current-limiting fuse has a 200,000-ampere interrupting rating; branch breakers have a 10,000-ampere interrupting rating. The panel is marked “Series-Rated.” _______
- c. Main breaker has a 22,000-ampere interrupting rating; branch breakers have a 10,000-ampere interrupting rating. The panel is marked “Series-Connected.” _______
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Approximately 75 percentage of the fault are either _____ or permanent LG Faults.
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In a short-circuit test on a 3-pole, 110 kV circuit breaker.
Power factor of the fault= 0.4.
Recovery voltage= 0.95 times (full line voltage)
The breaking current was symmetrical the restriking transient had a natural frequency of 15000 c/s. Determine the average rate of rise of restriking voltage. (The natural is grounded and the fault involves earth). Explain in details.
3.On a double line-to-ground faultImmersive reader
A) The short-circuit currents in the faulted phases are equal.
B) The voltages at the fault point on the faulted phases are zero.
C) The phase not involved in the fault has a zero voltage at the fault point.
D) There are no circulating currents through the neutrals to ground.
E) N. A.
Chapter 28 Solutions
Electrical Wiring Residential
Ch. 28 - What is the minimum size service for a one-family...Ch. 28 - Prob. 2RCh. 28 - Prob. 3RCh. 28 - Prob. 4RCh. 28 - Prob. 5RCh. 28 - Prob. 6RCh. 28 - Prob. 7RCh. 28 - List the standard sizes of fuses and circuit...Ch. 28 - Prob. 9RCh. 28 - Using the method shown in this unit, what is the...
Ch. 28 - State four possible combinations of service...Ch. 28 - Which Code section states that all overcurrent...Ch. 28 - All electrical components have some sort of...Ch. 28 - Arc-fault damage is closely related to the value...Ch. 28 - The utility company has provided a letter to the...Ch. 28 - While working on the main panelboard that is...Ch. 28 - Repeat problem 16 for a main service panel that...Ch. 28 - NEC ______________________________ generally...Ch. 28 - Prob. 19RCh. 28 - Prob. 20RCh. 28 - Overcurrent devices must be accessible. (True)...
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- A line to ground fault occurs on the terminals of an alternator, sequence voltages and sequence currents during this fault are Vao = -0.3 pu Val = -0.4 pu Va2 = -0.7 pu Iao = 1a1 = 1a2 = -j2 pu If zero sequence impedance is j0.05pu then what will be neutral to ground impedance placed approximately,arrow_forwardIn a short-circuit test on a 3-pole, 220 kV circuit breaker. Power factor of the fault = 0.8 Recovery voltage, 1.90 times (full line voltage) The breaking current was symmetrical the restriking transient had a natural frequency of 30000 c/s. Determine the average rate of rise of restriking voltage. (The natural is grounded and the fault involves earth).arrow_forwardcomplet The equivalent reactance of the double circuit line under post fault condition is................than fault condition.arrow_forward
- In a short circuit test on 132 kV, 3-phase system, the breaker gives the following results: Power factor of the fault = 0.45. Recovery voltage 0.9 time of full line voltage. The breaking current is symmetrical. The restriking transient has a natural frequency of 15 kHz. Calculate the rate of rise of restriking voltage (RRRV) in the following types of faults: (1) Grounded fault (2) Undergrounded fault.arrow_forwardIn which of the following faults symmetrical component method is not required a. Line to line fault O b. Double line to ground fault lon O c. Single line to ground fault O d. Three phase balanced fault Clear my choice pagearrow_forwardIf an unsymmetrical fault occurs on phase C of a transmission line, what would make the fault symmetrical? A. if phase C of the transmission line opens B. If phases A and B become faulted C. If two different faults occur on phas a and barrow_forward
- Q.3 When a line-to-ground fault occurs, the current in faulted phase 'a' is 100A. The zero-sequence current in phase 'c' isarrow_forwardData obtained from a short circuit test on a 132 kV 3-phase circuit breaker with earthed neutral are as follows: -the power factor fault was 0.3. -the recovery voltage was 0.75 of the full line value. -the breaking current was symmetrical. -the restriking transient had a natural frequency of 1600 Hz. Estimate the rate rise of the recovery voltage. Assume that the fault is grounded.arrow_forwardA protection system engineer is planning to provide the complete protection, he can achieve this by ___________ a. two phase fault relays and three earth fault relays b. a two phase fault relays and three earth fault relays c. three phase fault relays and two earth fault relays d. a two phase fault relays and two earth fault relaysarrow_forward
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