【數據中心設計】CDCP 學習筆記 - 數據中心 (Part 6-6) - Data Centre Design - Power Infrastructure

UPS電池技術的種類 Main battery technologies for UPS

• Flooded cell 滿槽鉛酸電池
• Sealed Lead Acid (SLA/VRLA) 密封式鉛酸電池
• Lithium-Ion (Li-ion) 鋰離子電池（鋰電池）
• Nickel-Cadmium (Ni-Cd) 鎳鎘電池

Flooded cells 滿槽鉛酸電池

• Wet or Vented cells
• 500 kVA and above
• Pros
• Long life span (typically 15 - 20 years)
• Able to operate at high currents
• Cons
• Must be stored in special, vented rooms （產生hydrogen.，氫氣易燃）
• Requires maintenance (water replenishment) （需要一段時間填充distilled water蒸餾水）
• Electrolyte requires special handling (burns)（需要添加電解液）
• Can only be used in one (upright) position

SLA / VRLA 密封式鉛酸電池

• SLA (Sealed Lead Acid)（密封式鉛酸電池）
• VRLA (Valve Regulated Lead Acid)（閥控式鉛酸電池）
• 5 years of design life
• 10/12 years of design life
• 設計壽命受到各種因素影響
• Design life does not equal service life（設計壽命一般長於使用壽命）
• Number of discharges and level of discharge circle（放電次數和放電深度影響使用壽命）
• Ripple voltage（電壓波動對電池影響）
• Ambient temperature（環境溫度對電池影響）
• Average service life
• 5 years design approx. 3-4 years
• 10 years design approx. 7-8 years

• Pros
• Attractive price
• No memory effect
• Low self-discharge（大約4-6個月後才需要充電）
• Cons
• Slow recharging (8 hours or more)（充電至少8-12個小時）
• Must always be stored in a charged state
• Sulphate destroys plates
• Can't stand high temperatures（電池需要安裝在有冷氣的房間）

Lithium-ion (Li-ion) 鋰離子電池

• Pros
• Long lifetime (>10 years)
• Smaller footprint and less weight（在香港，體積小成為重要考量因素，一般是Lead acid體積的三分之一）
• 10 times more discharge cycles
• Allows for fast charging（較Lead acid充電速度提升4倍以上）
• Cons
• Very expensive (3 times more than SLA)（成本已經逐年下降，很多香港小型數據中心已經逐步採用鋰電池）
• The battery management system is required to prevent, unsafe temperatures during charging/discharging
• Stricter transportation regulations

Nickel-cadmium（Ni-Cd）鎳鎘電池

• Pros
• Long lifetime (20 years)
• Able to work in high ambient temperature
• Reliable / predictable life
• Allows for fast charging
• Cons
• Need special charger in UPS
• Memory effect
• Very expensive (4-6 times more than SLA)
• Expensive to dispose of high chemical content（不環保，不推薦）

電池如何測試？Battery testing and testers

• Most UPS have an internal battery test（大多UPS會具備電池的自檢功能）
• A string level test only gives an indication
• Recommended to test batteries every 3-6 months at the block level（一般情況都需要定期檢查電池狀況）
• Testing should be performed at:
• Floating: battery status whilst UPS is running in normal / online mode and batteries are charged
• Under load: input power is turned off i.e. all the power to the load is provided by the batteries
• Spot check / continuous monitoring systems（電池自主監測功能可以實時監測電池狀態）
• Two types of battery testers
• Voltage
• Impedance/Resistance
• Thermographic scanning（通過觀察各設備溫度來檢測熱量）
• 相關標準——ANSI/NFPA 70B, SS507 indicate a yearly scan
• What to scan?
• All main switchboards and PDUs
• All connections and breakers of high-power equipment
• Isolation Transformers
• UPS
• Gen-set
• Main power cables (three-phase) and Bus Bar
• Busbar Trunking (BBT)
• Don't forget the neutral
• Critical rack / equipment / breakers