Presentation on theme: "EE4503 Electrical Systems Design"— Presentation transcript:
1EE4503 Electrical Systems Design Protective DevicesandProtective Devices Cooordination
2Topics LV protective systems Protective Devices Protective Devices Coordination
3Low Voltage Protective Systems Fully Rated Protective SystemSelective Protective SystemCascade Protective System
4Protective Systems Fully Rated Protective System All devices are able to withstand the maximum short circuit current. (Interrupting Capacity)Highest CostNo need to prioritize the devices
5Protective Systems Fully Rated Protective System If short circuit at F2 is 30kA and F1 is 10kAA, B, C: 𝐼 𝑐𝑢 =30𝑘𝐴D, E, F: 𝐼 𝑐𝑢 =10𝑘𝐴Electrical Systems Design: ประสิทธิ์ พิทยพัฒน์
6Protective Systems Selective 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.
7Protective Systems Selective Protective System A, B, C: 𝐼 𝑐𝑢 =10𝑘𝐴D, E, F: 𝐼 𝑐𝑢 =5𝑘𝐴There are two kindsFullyPartiallyElectrical Systems Design: ประสิทธิ์ พิทยพัฒน์
8Protective Systems Fully Selective Protective System The selectivity is on the full range of short current.A & B are selective more than 10𝑘𝐴Electrical Systems Design: ประสิทธิ์ พิทยพัฒน์
9Protective Systems Partially Selective Protective System The selectivity is only on a certain range of short current.A & B are selective up to 5𝑘𝐴Electrical Systems Design: ประสิทธิ์ พิทยพัฒน์
10Protective Systems Cascade 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.
11Protective Devices Coordination Overlay the plot of tripping curve of each protective devicesIn general, no crossing of tripping curveLower current (downstream devices) branch will be tripped faster.Higher current (upstream devices) branch will be tripped slower.
13Reference Electrical Systems Design: ประสิทธิ์ พิทยพัฒน์ Device_Coordination.pdfCoordination of LV protection devices: Schneider ElectricDepend on the area, end-user can connect to the “meter” of the authority in three ways.