BreakerStat: Current Monitoring System

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Breaker-StatCurrent Monitoring System

• Mid-term Presentation
• October 4,2006

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Presenters
Deven Patel
Stephanie Forman
Matthew Forman
Vishwas Sankaran
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Overview

• Problem Statement
• Solution
• Safety
• Recap of Design I
• Hardware Implementation
• Software Implementation
• Breaker-Stat Design Set-up
• Manufacturability
• Packaging
• PCB manufacturing
• Project refinements/changes
• Test Plan
• Timeline

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Problem Statement

• Tools currently utilized by industries today
  provide inadequate means or minimum capabilities
  of monitoring power distribution.
• OPTImizer informs personnel of circuit
  breakers operating condition, i.e. a tripped
  breaker.
• Pico Current Monitoring Kit logs data for
  optional analysis via download.
• The inadequacies may lead to unforeseen problems
  arising, which in turn, may become potentially
  dangerous.

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Solution

• Effectively monitor the power distribution
  continuously by incorporating the following
  features
• Graphical User Interface
• Tripped breaker alert
• Overloaded status indicator
• Microsoft Access Database
• History log for trend analysis
• Wireless implementation
• 802.15.4 standard serving as the communication
  medium

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Safety

• Assists in keeping critical equipment online.
• Hospital Environments
• Added safety precautions to patients
• Functions without causing harmful interference
  with other devices.
• Operates on a 2.4 GHz unlicensed band

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Recap
A Current Monitoring System with the following
features

• Monitors
• Wirelessly
• Multiple Load Center
• Multiple Branch Circuit
• Overload Warning Indicator
• Breaker Trip Indicator
• Microsoft Windows 2000 and XP Compatible

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Hardware Components

• Current Transformers (CT)
• Difference Amplifier
• Microprocessor
• Wireless Transceiver

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Components (cont)

• Current Transformer
• Measures Current
• Placed at each breaker
• Sizes are application dependent
• Difference Amplifier (INA159)
• Gain of 0.2
• DC offset of Vref/2

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Components (cont)

• Microchip (PIC18F4620)
• 10 Bit ADC
• 13 channels
• 36 I/O pins
• Wide operating voltage range
• 2.0V 5.5V

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Overview

• Problem Statement
• Solution
• Safety
• Recap of Design I
• Hardware Implementation
• Software Implementation
• Breaker-Stat Design Set-up
• Manufacturability
• Packaging
• PCB manufacturing
• Project refinements/changes
• Test Plan
• Timeline

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Software Implementation

• True RMS
• Sampling Method
• Sampling Process
• GUI

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True RMS

• Only True RMS will give accurate data
  measurements
• Since all waveforms will not be pure sinusoids,
  the True RMS equation is implemented

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Sampling Method

• To achieve the most accurate measurements, the
  PIC is used to sample the incoming waveform.
• Sampling Rate 2500 samples/sec
• Window Size 2 seconds

Example of Window Size
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Sampling Method Problem

• Since the PIC does not like negative values, the
  Difference Amplifier is used to offset the
  waveform.

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Difference Amplifier

• INA159
• Constant DC offset
• Gain

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Sampling Process

• CTs produce, from the primary current, a
  proportional secondary current.
• Burden Resister creates an AC output voltage.
• Difference Amp provides the DC offset.
• VOUT applied to input ports of the PIC.
• PIC perform A/D conversion and acquires a mean
  squared value.

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Graphical User Interface

• Graphical User Interface
• Performs calculations and displays current
  reading
• Provides spreadsheet of past breaker info.

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Breaker-Stat Design Setup
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Overview

• Problem Statement
• Solution
• Safety
• Recap of Design I
• Hardware Implementation
• Software Implementation
• Breaker-Stat Design Set-up
• Manufacturability
• Packaging
• PCB manufacturing
• Project refinements/changes
• Test Plan
• Timeline

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Manufacturability

• 2 different modules (house the PCBs)
• Load center module
• Wall-mounted unit
• Located near the breaker
• Wireless transmitter
• PC module
• User-preferred location
• USB connection from the module to the PC
• Wireless receiver
• Size no larger than (4 (W) x 4 (H) x 3 (D))

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Packaging
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Manufacturability
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PCB

• Implemented using Eagle software
• Basic layout of board given below
• Includes following main components
• PIC18F4620 44 pin microcontroller
• 2 Differential Amplifiers provide gain of 0.2
• USB connection for GUI
• RJ11 phone jack
• Voltage Reference (2.5V)
• Daughter Card

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PCB (schematic)
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PCB (schematic)
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PCB (schematic)
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PCB (Layout)
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Overview

• Problem Statement
• Solution
• Safety
• Recap of Design I
• Hardware Implementation
• Software Implementation
• Breaker-Stat Design Set-up
• Manufacturability
• Packaging
• PCB manufacturing
• Project refinements/changes
• Test Plan
• Timeline

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Project Refinements/Changes

• Printed Circuit board
• Packaging
• Microchip Zigbee Stack v3.5 ? MSSTATE_LRWPAN
• Created by Dr. Reese
• Smaller, easier to understand stack
• Add router to increase distance
• Fix GUI interface issue
• Improve visual appearance of GUI

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Project Refinements/Changes
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Project Refinements/Changes

• Printed Circuit board
• Packaging
• Microchip Zigbee Stack v3.5 ? MSSTATE_LRWPAN
• Created by Dr. Reese
• Smaller, easier to understand stack
• Add router to increase distance
• Fix GUI interface issue
• Improve visual appearance of GUI

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Project Refinements/Changes
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Test Plan

• Unit Testing
• Current measurements
• Wireless communication via HyperTerminal
• Interaction between GUI and coordinator
• Final Product Testing
• 2 loadcenters/2 breakers per load center
• Simrall
• Residential environment

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Timeline
11.14 Packaging/ GUI Interfacing
10.17 Complete Wireless Code
10.10 Complete Code Port
11.29 Final Presentation
11.21 Final Product Testing
10.14 Add Router
10.22 Populate PCBs