a) Determine the setting of the overload protection of the circuit breaker intended to protect a 50hp, 380V, IV-pole motor, powered by a unipolar copper-PVC conductor circuit, with a cross-section of 25mm², installed in a buried conduit: The short-circuit current at the motor terminal is 5KA. It is assumed that the overload current of the conductor throughout its useful life is controlled and will not exceed 100 hours for 12 consecutive months or 500 hours throughout the useful life of the conductor. Data: fp = 0.86; efficiency = 0.92 a) Determine the minimum operating time of the circuit breaker in the event of a short-circuit at the motor terminals.

a) Determine the setting of the overload protection of the circuit breaker intended to protect a 50hp, 380V, IV-pole motor, powered by a unipolar copper-PVC conductor circuit, with a cross-section of 25mm², installed in a buried conduit: The short-circuit current at the motor terminal is 5KA. It is assumed that the overload current of the conductor throughout its useful life is controlled and will not exceed 100 hours for 12 consecutive months or 500 hours throughout the useful life of the conductor. Data: fp = 0.86; efficiency = 0.92 a) Determine the minimum operating time of the circuit breaker in the event of a short-circuit at the motor terminals.

Electric Motor Control

10th Edition

ISBN:9781133702818

Author:Herman

Publisher:Herman

Chapter14: Phase Failure Relays

Section: Chapter Questions

Problem 1SQ: What is the purpose of phase failure relays?

See similar textbooks

Similar questions

Report:- 1. Plot (total core loss / cycle) as a function of frequency. 2. Evaluate (K & K2 )corresponding to value of (voltage & frequency). 3. Calculate hysteresis and eddy current losses at rated voltage and frequency.
A 100/5A 5P10 bar primary current transformer supplies an over current relay set at 20 % pick up and it has a burden of 5VA. The CT has 50 turns on its secondary operating at 50 Hz and the fault current is 10 times the relay setting. Assume the cross sectional area of the core is 0.003 m2. Calculate: (1) The knee point voltage (ii) The flux density of the core (iii) Accuracy limit factor
If we have a 50G ground relay connected to a flux summation CT of 50:5. If we measure the phase currents to be, la = 2002-14° b = 1982-120° Ic=77z+120° How much current will flow into the 50G relay?
h.1. In an alternating-current system, the maximum size for a copper grounding electrode conductor isA. 250 kcmil.B. 3/0.C. 500 kcmil.D. 4/0. h.2. The figure shows a fault condition in an ungrounded electrical system. Which of the following will occurbecause of the fault in this system?A. Only the overcurrent protector at Point A will trip open.B. The ground fault will heavily damage the service.C. Nothing will happen until a second ground fault occurs.D. The overcurrent protection will trip, shutting off all the line side power.
b. traveler (ti)*) D. Several factors or conditions can cause conductors to overheat, but often overlooked is the possibility A a. induction heating b. ambient temperature C. the size of conductors d. grounding
Which of the following is?are an application of electrimagnets. A) relays, B) generations, C) magnetic cluches, D) all of the above. When using the left hand rule for conductor, the fingers point in the direction of_______. A) the electron flow, B) the field around the conductor, C) both a and b, D) none Upon what does the strength of an air-cored coil depend?A) amount of current flow, B) number of turns, C) permeability of the core, D) all above
What is the purpose of phase failure relays?
solve with explanation.
Q2/ Design a 4-pole wave winding for an armature with 21 slots. Assume single turn coils and two conductors per slot. (35 mark)
Please help me with these MCQ 1. stator windings are connected in _____ types 2. Circuit resistance is checked by connecting a(n) ______ to the positive battery terminal and the output, or battery terminal of the AC regenerator. 3. Slip rings and brushes A: Mount on the rotor shaft B: Conduct current to the rotor field coils C: Are insulated from each other and the rotor shaft D: All of the above
A three phase,Y connected, 215 V (line to line), 7.5 kW, 60 Hz, three pole IM has the following parameter values in Ohm/phase referred to the statorR₁ = 0.294 Ohm, R₂ = 0.144 Ohm, X₁ = 0.203 Ohm, X₂ = 0.409 Ohm, Xm = 10.25 Ohm.The total friction,windage and core losses may be assumed to be constant at 350 W independent of load. For a slip s = 0.02, compute the followingsa) Stator Currentb) Power Factor(pf)c) Rotor Speedd) Power Output(Shaft)e) Output(Shaft) Torquef) Efficiency(n)
Draw a block diagram of a phase-locked loop (PLL) and briefly explain its operation.