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Power Supplies 電源 (P.39)
Learning Objectives 學習目標
• Identify power supply connectors.
識別電源連接器。
• Recommend and install an appropriate power supply given specific hardware to be powered.
根據要供電的特定硬件，建議並安裝適當的電源。
Power supply units (PSUs) are required in all computer systems, since computers are designed to run on direct current (DC), but our home and office outlets only provide alternating current (AC). For a computer to run well, it requires good, clean power from the outlet to the computer’s PSU. The PSU then converts the AC input into DC output to the various subsystems of the computer at the necessary voltages. The PSU creates heat in this transformation from AC to DC. Therefore, a good power supply fan is essential to remove the heat from the PSU and computer system. A power supply is a field replaceable unit (FRU) and should be replaced — never repaired — because the capacitors will hold voltage well after the PSU has been unplugged.
所有計算機系統都需要電源單元（PSU），因為計算機被設計為以直流電（DC）運行，但是我們的家庭和辦公室插座僅提供交流電（AC）。 為了使計算機正常運行，需要從插座到計算機PSU的電源乾淨整潔。 然後，PSU將交流輸入轉換為直流輸出，並在必要的電壓下將其輸入計算機的各個子系統。 PSU在從AC轉換為DC的過程中會產生熱量。 因此，良好的電源風扇對於消除PSU和計算機系統的熱量至關重要。 電源是一個現場可更換單元（FRU），應進行更換（切勿修理），因為在拔下PSU後電容器將保持良好的電壓。
Computer PSU, showing a space for the fan and an electric cord input.
計算機電源模塊，顯示風扇和電線輸入的空間。
Power supplies are rated in watts, with contemporary computer systems requiring 400 watts of power or more. Every device inside the computer requires power and receives it from the PSU. Therefore, the more devices there are inside the computer, the more power that is required from the power supply.
電源的額定功率為瓦特，當代計算機系統需要400瓦特或更高的功率。 計算機內部的每個設備都需要電源，並從PSU接收電源。 因此，計算機中存在的設備越多，電源所需要的功率就越大。
A technician should verify that the backward “UR” logo 
appears on the power supply, since this indicates that the power supply has been properly safety tested. When purchasing a new computer, the power supply will already have been selected based on the initial configuration of the machine, but if you are adding new components to the workstation, you will need to verify that the power supply has enough wattage to support the existing and new components. To do this, you need to determine the wattage by adding all the devices’ wattage together. If the device is measured in amps, multiply amps times voltage (A x V) to calculate the watts. Power supplies are not 100 percent efficient, nor are they rated to be 100 percent efficient. Therefore, you should always keep the total wattage under 70 percent of the rated wattage of the power supply to ensure proper computer operations.
技術人員應驗證電源上是否有向後的“ UR”徽標，因為這表明電源已經過正確的安全測試。 購買新計算機時，將已經根據計算機的初始配置選擇了電源，但是如果您要向工作站添加新組件，則需要驗證電源是否具有足夠的功率以支持現有電源。 和新組件。 為此，您需要通過將所有設備的瓦數相加來確定瓦數。 如果設備以安培為單位測量，則將安培乘以電壓（A x V）以計算瓦數。 電源效率不是100％，也不是額定為100％。 因此，應始終將總功率保持在電源額定功率的70％以下，以確保計算機正常運行。
Power supply specifications. 電源規格
Dual Voltage 雙電壓
Most of today’s computers are built around the world with different voltages. In the United States, power is delivered at 115–120 VAC (voltage alternating current) at 60 hertz. In Europe and Asia, the typical wall outlet provides 230–240 VAC at 50 hertz. If the power supply supports dual voltage, you need to ensure the correct setting is selected. In that situation, there should be a slider button that allows you to select the proper voltage. Slide the button to the appropriate voltage before plugging the power supply into the wall or damage to the computer can occur.
當今大多數計算機都是在世界各地以不同的電壓構建的。在美國，功率在60赫茲的115-120 VAC（交流電壓）下輸送。在歐洲和亞洲，典型的壁裝電源插座以50赫茲提供230-240 VAC。如果電源支持雙電壓，則需要確保選擇正確的設置。在這種情況下，應該有一個滑塊按鈕，可讓您選擇合適的電壓。在將電源插頭插入牆上之前，請將按鈕滑動至適當的電壓，否則可能會損壞計算機。
What do you think would happen if we selected the wrong voltage before plugging it in? Well, if we are in Europe and expecting 230 VAC from the wall, but set the switch to 110 VAC (the United States standard), the power supply would receive an overvoltage condition, damaging the power supply and possibly starting a fire. If instead we took a European PC, which expects 230 VAC, and plugged it into a United States electrical outlet providing 110 VAC, we would get an undervoltage condition, and the computer would not start up.
如果我們在插入之前選擇了錯誤的電壓，您會怎麼辦？好吧，如果我們在歐洲並期望牆壁有230 VAC的電壓，但將開關設置為110 VAC（美國標準），則電源將出現過壓狀況，從而損壞電源並可能引發火災。如果取而代之的是，我們帶了一個歐洲PC，該PC期望提供230 VAC的電源，然後將其插入提供110 VAC的美國電源插座，則將出現欠壓情況，並且計算機將無法啟動。
Power supply port and on/off switch within a metal honeycomb mesh to allow for power supply ventilation.
金屬蜂窩網內的電源端口和開/關開關可允許電源通風。
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