Building Power Issues and Mitigations

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Power Issues

• A surge is a brief increase in voltage, while a spike is an intense surge

  • caused by machinery and other high-power devices being turned on or off and by lightning strikes
  • can cause interference to computer to crash, reboot, or damage it

• Under-voltage event is when devices that require high-starting current to cause building voltage to dip briefly

  • could cause computer equipment to turn off

• Power failure is complete loss of power

  • caused by:
    • blackout from power grid
    • equipment failure
    • accidental cutting of cables during construction work
    • fuse blown or circuit breaker tripped

Mitigation

Surge Suppressors

• rated according to various national and international standards
  • E.g. Underwriters Laboratory (UL) 1449
• 3 Important Characteristics
  • Clamping voltage
    • Defines the level at which the protection circuitry will activate, with lower voltages (400 V or 300 V) offering better protection
  • Joules rating
    • The amount of energy the surge protector can absorb, with 600 joules or more offering better protection
    • Each surge event will degrade the capability of the suppressor
  • Amperage
    • The maximum current that can be carried or basically the number of devices you can attach
    • you should only use 80% of the rated capacity

Battery Backups

• an uninterruptible power supply (UPS) will provide a temporary power source in the event of complete power loss
  • time allowed by a UPS is sufficient to activate an alternative power source
  • if no alt power supply, then will give enough time to save and shutdown the machine
  • key characteristics
    • volt-amperes (VA) rating is the maximum load the UPS can sustain
      • to calculate,
        • sum the wattage of all the devices that will be attached to the UPS
        • and multiply by 1.67 to account for a conversion factor
      • E.g., if you have a 10 W home router and two 250 W computers, the VA is (10 + 250 + 250) * 1.67 = 852 VA
        • A 1K VA UPS model should therefore be sufficient.
    • Runtime is the number of minutes that the batteries will supply power
      • measured in amp hours (Ah)