Power and Noise

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Power and Noise

• Kevin Shaffer
• Fort Hays State University

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Learning Objectives

• Power and Noise Concepts
• Concerns and Dangers
• Solutions

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Power and Noise Concepts

• AC-DC, Noise, Grounding
• Current and voltage
• Variables and Equipment

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Alternating current, direct current, and the
difference

• DC is one-way
• AC is push-pull at 60 cycles per second
• No net current flow for AC

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Noise and how it corrupts digital pulses
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More definitions

• Grounding -- low resistance current path to earth
• Electrostatic discharge -- build up of voltage
  potential
• Conductors and Insulators -- Low resistance and
  high resistance to current flow

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AC wires and wiring problems

• Normal Mode
• Problem between Hot Wire and Neutral Wire
• Common Mode
• Problem between Safety Ground and either Neutral
  or Hot wire

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Electrical ground and signal reference ground

• Electrical Ground
• Low resistance path to earth
• prevent build up of hazardous voltage
• affects the Signal Reference Ground

• Signal Reference Ground
• sets the zero value for measuring the voltage of
  a pulse
• connected to the electrical ground

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Variable Current and Voltage

• Sags
• Brownouts
• Spikes
• Surges
• Oscillations

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Surge Suppressors

• Protection from voltage spikes
• Some are single use
• Redirect spikes to ground

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Uninterruptible Power Supplies

• Temporary
• Protects from sags and brownouts
• Not as good as a generator

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Dangers and Concerns

• Grounding issues
• multi-floor and multi-building sites
• poor installation
• Lightning
• Improper use of surge protectors
• Electrical Noise
• A UPS is not a generator

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Solutions--Grounding Issues

• Get your own transformer
• Q Expensive?
• A
• Breaker boxes for each office area
• Avoid the antenna effect
• Watch your electrical contractor

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Solutions--Lightning

• Use Fiber between buildings
• Check grounding
• Lightning rod

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Solutions--Surge Suppressorsand UPSs
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Solutions--Noise

• Breaker Boxes for each work area
• Never exceed standards for maximum cable lengths
  (both fiber and copper)

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Solutions--UPS and Generators

• Use intelligent online UPS for mission critical
  equipment
• Use UPS for all intermediate and end nodes where
  affordable
• A UPS is not a generator

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Power and Noise

• Kevin Shaffer
• Fort Hays State University