Q4 An industrial motor is to be protected against overload. Its nameplate details are three-phase 3.3 kV, 500 kW, 75 % efficiency and 0.85 power factor. The motor can withstand 15% overload continously. The time constant of heat withstand characteristic is 10 minutes. A thermal relay is connected across a C.T. of 120/1 ratio. The time constant of the relay is also 10 minutes. The range of settings is 70 % to 150 % of 1 A in steps of 5 %. Suggest the proper relay setting for this application

Q4 An industrial motor is to be protected against overload. Its nameplate details are three-phase 3.3 kV, 500 kW, 75 % efficiency and 0.85 power factor. The motor can withstand 15% overload continously. The time constant of heat withstand characteristic is 10 minutes. A thermal relay is connected across a C.T. of 120/1 ratio. The time constant of the relay is also 10 minutes. The range of settings is 70 % to 150 % of 1 A in steps of 5 %. Suggest the proper relay setting for this application

Power System Analysis and Design (MindTap Course List)

6th Edition

ISBN:9781305632134

Author:J. Duncan Glover, Thomas Overbye, Mulukutla S. Sarma

Publisher:J. Duncan Glover, Thomas Overbye, Mulukutla S. Sarma

Chapter12: Power System Controls

Section: Chapter Questions

Problem 12.4P

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