Delmar's Standard Textbook Of Electricity
7th Edition
ISBN: 9781337900348
Author: Stephen L. Herman
Publisher: Cengage Learning
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A 25-HP, continuous-duty, three-phase squirrel-cage induction motor is connected to a 240-volt line. The conductors are run in conduit to the motor. The motor does not have a NEMA design code listed on the nameplate. The termination temperature rating of the devices is not known. Copper conductors with THWN insulation are to be used for the motor connection. What size conductors should be used?
All answers should be written in complete sentences. Calculations should be shown in detail, and Codereferences should be cited when appropriate. Unless otherwise stated, all conductors are copper type THHN, and the supply is AC.
1. What is the minimum conductor ampacity, overload protection, and dual-element fuserating for a circuit supplying a 560-volt, 3-phase, code J, 40°C, 125-horsepower motorwith a nameplate full-load current of 115 amperes?
A 30- hp squirrel cage induction motor is connected to a 240-volt three phase feeder. The motor is to be replaced with a 50-hp squirrel cage induction motor connected to 480 volts. The motor has a nema code b, a full load current of 49.8 amps, and an sf of 1.10. the present conductors are 3 awg copper with thwn insulation. Are these conductors sufficient to connect to the 50-hp motor or will they have to be replaced
Chapter 34 Solutions
Delmar's Standard Textbook Of Electricity
Ch. 34 - Which NEC table is used to determine the full...Ch. 34 - A 5-HP single-phase motor is connected to 208...Ch. 34 - A 10-HP single-phase motor is connected to 240...Ch. 34 - A 75-HP synchronous motor is connected to a...Ch. 34 - A squirrel-cage induction motor has a nameplate...Ch. 34 - A squirrel-cage motor has a nameplate current...Ch. 34 - A 100-HP three-phase squirrel-cage induction motor...Ch. 34 - A 60-HP synchronous motor is connected to 240...Ch. 34 - Prob. 9RQCh. 34 - Both the motors and the feeder in Question 9 are...
Ch. 34 - A 30-HP squirrel-cage induction motor is connected...Ch. 34 - Refer to the preceding Practical Application. When...Ch. 34 - Refer to the first Practical Application in this...Ch. 34 - A 10-HP single-phase motor is connected to 240...Ch. 34 - A 500-HP synchronous motor is connected to 2300...Ch. 34 - A 30-HP three-phase squirrel-cage induction motor...Ch. 34 - A 75-HP synchronous motor is connected to a...Ch. 34 - Prob. 5PPCh. 34 - A 350-HP squirrel-cage induction motor is...Ch. 34 - Three squirrel-cage motors are connected to a...
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- A 350-HP squirrel-cage induction motor is connected to a 480-volts three-phase feeder. The nameplate lists the following: HP 350, Service factor 1.10, Full-load amps 408, NEMA Code B. The conductors are to be copper with THWN insulation, and 600:5 current transformers are used to reduce the current supplied to the overload heaters. The motor circuit is protected with dual-element time delay fuses. Determine the conductor size, overload heater size using the chart shown in Figure 34-7, the NEMA and IEC starter sizes, and the fuse size for this installation.arrow_forwardA 100-HP three-phase squirrel-cage induction motor is connected to 480 volts. The conductors supplying the motor are copper with THW2 insulation. The nameplate lists a full-load running current of 118 amperes, NEMA Code B, and a service factor of 1.00. Current transformers with a ratio of 200:5 are used to reduce the current supplied to the overload heaters. The motor is protected with dual-element time delay fuses. Determine the conductor size, overload heater size using the chart in Figure 34-7, NEMA and IEC starter sizes, and fuse size for this motor.arrow_forward460VAC squirrel cage, 60 hp, 3 phase induction-type AC motor, is to be controlled with 220VAC rated magnetic contactor. Control circuit will be supplied with 110VAC. What is the full-load current and the conductor size.arrow_forward
- All answers should be written in complete sentences. Calculations should be shown in detail, and Codereferences should be cited when appropriate. Unless otherwise stated, all conductors are copper type THHN, and the supply is AC. 1. What are the minimum allowable ampacities of the phase conductors and the neutralconductor that are to supply a 2-phase, 3-wire, 230-volt, 30-horsepower motor?arrow_forwardAll answers should be written in complete sentences. Calculations should be shown in detail, and Codereferences should be cited when appropriate. Unless otherwise stated, all conductors are copper type THHN, and the supply is AC. 1. What size conductor would be required to supply three motors connected to a 440-volt, 3-phase branch circuit? Motor #1 is a 50-horsepower, code B induction motor;motor #2 is a 40-horsepower, code H induction motor; and motor #3 is a 50-horsepower, code J induction motor.arrow_forwardA 40 hp Squirrel cage Induction-type, 230 volts rated 3 phase motor. It has a code rating of "B" and an ambient temperature of 40 degree celcius. Conductor code RHW copper will be used. Determine its conductor size.arrow_forward
- All answers should be written in complete sentences. Calculations should be shown in detail, and Codereferences should be cited when appropriate. Unless otherwise stated, all conductors are copper type THHN, and the supply is AC. 1. What is the minimum conductor size, overload protection, and inverse-time circuitbreaker rating for a circuit supplying a 230-volt, 3-phase, code A, 40°C, 75-horsepower synchronous motor operating at an 80% power factor with a nameplate full-load current of 185 amperes?arrow_forwardYour Answers may be presented through Discussions, Drawings/Figures/Diagrams, Reference to NEC/PEC and Computations 6. What are the minimum allowable ampacities of the phase conductors and the neutral conductor that are to supply a 2-phase, 3-wire, 230-volt, 30-horsepower motor?arrow_forward#10 When selecting conductors, from where is the motor full - load ampere rating to be takenarrow_forward
- A 460VAC rated, 60 Hz, 125-Hp Three-phase induction type motor is to be connected for across-the-line starting. The nameplate indicates the motor’s maximum ampere rating, 160A. It has a NEMA code letter B. The ambient temp of the installation place is and TW copper will be used. Short-circuit protection device that will be used is Inverse Time Breaker. Calculate the Conductor size.arrow_forwardAirframe Electrical System Question: What is the maximum acceptable voltage drop from the voltage source to the utilization equipment's ground in a 28 volt system? (Source: FAA AC 43.13-1B/2B)arrow_forwardYour Answers may be presented through Discussions, Drawings/Figures/Diagrams, Reference to NEC/PEC and Computations. 8. What is the minimum conductor ampacity, overload protection, and dual-element fuse rating for a circuit supplying a 560-volt, 3-phase, code J, 40°C, 125-horsepower motor with a nameplate full-load current of 115 amperes?arrow_forward
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