Medium Voltage (MV) High Voltage (HV) （中压(MV)及高电压(高压)）.pdf

Medium Voltage (MV) High Voltage (HV) Training Module 6 Date of the presentation Electrical System Basics MV vs. HV - Definitions • Differences between USA and the rest of the world • IEC define a high voltage fuse as a fuse-link rated for 3 phase systems above 1kV to 72.5 kV • IEEE define a medium voltage fuse-link as a fuse rated for single and 3 phase systems between 1kV and 38kV Cliquez et modifiez le titre Module 6 - page 2 2 Electrical System Basics • Generation voltage 10 kV-25kV MV (Medium Voltage) • Transmission voltage HV (High Voltage) – 132kV to 475 kV Or EHV (Extra high voltage) – 500 kV to 800 kV • Distribution voltage MV (Medium Voltage) – 1.1kV to 72.5 kV Cliquez et modifiez le titre • Low voltage LV 1 V to 1kV Module 6 - page 3 3 Electrical System Basics Cliquez et modifiez le titre Module 6 - page 4 Why High Voltage Power = Volts X Amps If we increase voltage, we can decrease current If we decrease current, we can use smaller conductors (less copper) and have lower losses (around 7% typical) Transmit and distribute at high and medium voltages Typically on overhead line systems Cliquez et modifiez le titre Module 6 - page 5 5 Why Overhead Line Systems • Predominantly driven by cost For 1 kilometre of overhead line £5,000 • For 1 kilometre of underground cable £25,000 • Overhead systems susceptible to faults permanent transient Cliquez et modifiez le titre • Need for protecti