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Power Supplies
Technicians should use surge protectors or surge suppressors to protect computers from power spikes and surges. These devices are specifically designed to absorb overvoltage conditions that would damage computers, printers, and monitors. While these devices will protect the computer from damage resulting from an overvoltage condition, they do not protect it from an undervoltage condition. Undervoltage is a condition that occurs when insufficient voltage is provided by the outlet to the computer. In situations where it is essential that the computer not lose power, technicians must install an uninterruptible power supply (UPS) to provide emergency power when a power failure (blackout) occurs or an undervoltage condition (brownout) occurs. The UPS runs the computer from its internal battery continuously and recharges the UPS’s battery while power is available. Once power is lost, the UPS continues to power the computer for up to 15 minutes (purportedly). This provides the user enough time to save work and safely power down the workstation. Another device that helps in undervoltage conditions is the standby power supply (SPS), which runs the computer directly from the wall outlet (AC power), but switches to the battery in less than a millisecond when a power outage occurs. An SPS device does not provide constant power, like a UPS device. For this reason, most technicians prefer UPS devices over SPS devices, so UPS devices are much more common in the marketplace. 技術人員應使用電湧保護器或電湧抑制器來保護計算機免受電湧和電湧的影響。這些設備經過專門設計，可以吸收可能損壞計算機，打印機和顯示器的過電壓情況。儘管這些設備可以保護計算機免受過壓狀況的損害，但它們不能保護計算機免受欠壓狀況的影響。當計算機的插座提供的電壓不足時，就會發生欠壓情況。在必須確保計算機不掉電的情況下，技術人員必須安裝不間斷電源（UPS），以在發生電源故障（停電）或發生欠壓情況（斷電）時提供應急電源。UPS會使用其內部電池連續運行計算機，並在有電時為UPS的電池充電。一旦斷電，UPS將繼續為計算機供電長達15分鐘（據稱）。這為用戶提供了足夠的時間來節省工作並安全地關閉工作站電源。備用電源（SPS）是在欠壓情況下提供幫助的另一種設備，該備用電源直接從壁裝電源插座（交流電源）運行計算機，但在斷電時不到一毫秒即可切換到電池。SPS設備不像UPS設備那樣提供恆定功率。因此，大多數技術人員更喜歡UPS設備而不是SPS設備，因此UPS設備在市場上更為普遍。
Uninterruptible power supplies are rated in various ways, including their runtimes, network support capabilities, automatic shutdown capabilities, and surge suppression. The runtime dictates the amount of time a computer will keep running on power from the UPS’s battery once source power is removed. Usually, you want to use a UPS with at least 15 minutes of runtime support. The bigger the battery, the longer the runtime. The runtime is calculated based on volt-amps, which is discussed in more detail in a later section. UPS devices can also have software that allows them to be connected to the network. Therefore, when the UPS notices a drop in power, it can send out a message to the users that the network is being shut down because of power loss. Some UPS devices support automatic shutdown of the connected computer or server, so that once a switch to battery power occurs, the UPS sends a shutdown signal to the connected machine. Finally, most UPS devices also provide surge suppression capabilities, rated in joules. 不間斷電源的額定方式有多種，包括其運行時間，網絡支持功能，自動關機功能和電湧抑制。運行時間規定了斷開電源後計算機將繼續使用UPS電池供電的時間。通常，您要使用具有至少15分鐘運行時間支持的UPS。電池越大，運行時間越長。運行時間是基於伏安計算的，這將在後面的部分中詳細討論。UPS設備還可以具有允許其連接到網絡的軟件。因此，當UPS注意到電源中斷時，它可以向用戶發送一條消息，通知您由於斷電而導致網絡正在關閉。某些UPS設備支持所連接的計算機或服務器的自動關機，因此一旦切換到電池電源UPS就會向所連接的計算機發送關機信號。最後，大多數UPS設備還提供以焦耳為單位的電湧抑制功能。
The last type of device technicians can use is called a power conditioner or line conditioner. These devices do not have any battery backup capability, but can rectify the power from a dirty power condition (where power fluctuates greatly) to a steady 115-120 VAC power condition. These devices can raise undervoltage conditions to normal levels, as well as cut overvoltage conditions back down to standard levels. This is very important if your systems are going to run from a backup generator, or if you are operating in an area with unstable power (such as in some developing countries). 技術人員可以使用的最後一種設備稱為功率調節器或線路調節器。這些設備沒有任何備用電池功能，但是可以將電源從骯髒的電源狀況（電源波動很大）整流為穩定的115-120 VAC電源狀況。這些器件可將欠壓條件提高到正常水平，並將過壓條件降低迴標準水平。如果您的系統要使用備用發電機運行，或者您在電力不穩定的區域（例如在某些發展中國家）運行，則這非常重要。
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