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EE4503 Electrical Systems Design

EE4503 Electrical Systems Design. Protective Devices a nd Protective Devices Cooordination. Topics. LV protective systems Protective Devices Protective Devices Coordination. Low Voltage Protective Systems. Fully Rated Protective System Selective Protective System

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EE4503 Electrical Systems Design

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  1. EE4503Electrical Systems Design Protective Devices and Protective Devices Cooordination

  2. Topics • LV protective systems • Protective Devices • Protective Devices Coordination

  3. Low Voltage Protective Systems • Fully Rated Protective System • Selective Protective System • Cascade Protective System

  4. Protective SystemsFully Rated Protective System • All devices are able to withstand the maximum short circuit current. (Interrupting Capacity) • Highest Cost • No need to prioritize the devices

  5. Protective SystemsFully Rated Protective System Electrical Systems Design: ประสิทธิ์ พิทยพัฒน์ • If short circuit at F2 is 30kA and F1 is 10kA • A, B, C: • D, E, F:

  6. Protective SystemsSelective Protective System • All devices are able to withstand the maximum short circuit current. (Interrupting Capacity) • Tripping Characteristic Curve of each devices are “selected” in the way that the device that is closer to the fault trips first.

  7. Protective SystemsSelective Protective System Electrical Systems Design: ประสิทธิ์ พิทยพัฒน์ • A, B, C: • D, E, F: • There are two kinds • Fully • Partially

  8. Protective SystemsFully Selective Protective System Electrical Systems Design: ประสิทธิ์ พิทยพัฒน์ • The selectivity is on the full range of short current. • A & B are selective more than

  9. Protective SystemsPartially Selective Protective System Electrical Systems Design: ประสิทธิ์ พิทยพัฒน์ • The selectivity is only on a certain range of short current. • A & B are selective up to

  10. Protective SystemsCascade Protective System • The upstream device has the faster tripping rate at the high current than the lower one. • The upstream device is able to withstand the maximum short circuit current while the downstream is lower capacity. • In case of high current short circuit the upstream handle the breaking function.

  11. Protective Devices Coordination • Overlay the plot of tripping curve of each protective devices • In general, no crossing of tripping curve • Lower current (downstream devices) branch will be tripped faster. • Higher current (upstream devices) branch will be tripped slower.

  12. Protective Devices Coordination http://www.poweranalytics.com/designbase/pdf/Protective_Device_Coordination.pdf

  13. Reference • Electrical Systems Design: ประสิทธิ์ พิทยพัฒน์ • http://www.poweranalytics.com/designbase/pdf/Protective_Device_Coordination.pdf • Coordination of LV protection devices: Schneider Electric

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