DANIEL LAWSON
Box Wrapper PLC
Disclaimer: This project was part of Udacity's "From Wire to PLC, A Bootcamp In Industrial Automation" course. I completed this project with help from the videos in the class and my final product was ultimately checked against the solution provided.
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Link to Course: https://www.udemy.com/course/from-wire-to-plc-a-to-z-compilation/
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I took Udemy's "From Wire to PLC, A Bootcamp In Industrial Automation" course because I became very interested in manufacturing after working at Tesla and wanted to learn more about it. The course covered topics such as:
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Basic electrical concepts and components and how they operate
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Traditional motor driving control circuits and modern motor driving equipment
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Protection components and how to choose them
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Wiring and cable sizing
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Sensors and their utilization in real projects
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Electrical Panel Troubleshooting
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Schematics drawing and design
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PLC programming using Ladder Logic, Structured Text, and Functional Block Diagrams
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Allen Bradley - RsLogix 500, RsEmulate 500 and Rslinx Training
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Human User Interface design and Animation
Completion Certificate
Box Wrapper Project
Goal: Design the control logic for a box wrapper machine and build an animated visual to simulate the machine.
Main Components
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Motor 1: to move the wrap up and down
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Motor 2: to rotate the platform under the box
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High limit switch: to sense when the wrap is at the top
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Low limit switch: to sense when the wrap is at the bottom
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Rotation count proximity sensor: to count the number of box rotations
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Wrap empty proximity sensor: to stop the machine when there is no more wrap
Example of a Box Wrapper
Choosing Power Components and Cabling
Motor 1
Given criteria:
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0.37kW 380VAC 3-Phase
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Speed control: 0.37kW VFD
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Distance from the panel: 1m
Calculations:
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I = W/(V*0.7*1.73) = 0.8A
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Overload not required
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From cable size table: 1.5mm diameter cable
Motor 2
Given criteria:
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0.55kW 380VAC 3-Phase
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Speed control: 0.55kW VFD
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Distance from the panel: 1m
Calculations:
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I = W/(V*0.7*1.73) = 1.2A
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Overload not required
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From cable size table: 1.5mm diameter cable
Total power = 0.37kW + 0.55kW = 0.92kW
Need 6m of 1x1.5mm cable
Choosing Sensors and their Cabling
Current = 12mA per PLC input = 12mA * 4 = 48mA
Power = 48mA * 24VDC = 1.1W
Need:
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3m of 2x0.75mm cable
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3m of 3x0.75mm cable
Current = 12mA per PLC input + 9mA per relay coil
Current = (12mA + 9mA) * 4 = 84mA
Power = 84mA * 24VDC = 2W
Choosing PLC and IO
Digital Outputs (12mA each)
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Motor 1 (rotation)
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Motor 2 (Up_Down)
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Motor 2 (Down_Up)
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Spare
Digital Inputs (12mA each)
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High limit SW
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Low limit SW
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Wrap proximity
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Count proximity
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Motor1 OVLD
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Motor2 OVLD
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EMGC stop
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Spare 1
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Spare 2
Analog Outputs (12mA each)
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VFD1 frequency
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VFD2 frequency
Current = DOs + DIs + AOs + Relays + PLC Internal + VFD Internal
Current = (12mA * 4) + (12mA * 9) + (12mA * 4) + (9mA * 4) + 20mA + (5mA * 2) = 246mA
1A 24VDC power supply with shortcircuit protection is more than enough.
Choosing Circuit Breakers
Main Breaker
Total power = 920W + (PLC IO + PLC internal power + Relay) + 20% = 1.1kW
Total current = 1.1kW / (380 * 0.7 * 1.73) = 2.4A * 10 (worst case inrush current) = 24A
Cable length from power source to breaker = 10m
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Is 1.5mm enough? In other words, is voltage drop less than 3%?
Voltage drop % = (1.73 * current * cable_imp._per_meter * cable length * 100) / voltage source
Voltage drop % = (1.73 * 24 * 0.0138 * 10 * 100)/380 = 1.5% < 3% -- 1.5mm is acceptable
MCBs
From cable size table, max current for 1.5mm cable is 25A. Main input MCB should be rated at 25A type C to account for inrush currents.
Since these are only for switching, any rating higher than the device max rating is enough.
Internal Panel Cabling
Follow US color coding
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DC Control (Relays & PLC): 0.75mm
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VFDs: 1.5mm
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Main circuit breaker input: 1.5mm
Fuses
Since total PLC current is 246mA, choose next highest fuse which is 500mA.
Schematics
MCB Schematic
Control Schematic
Motors Schematic
Sensors and Button Schematic
CodeSys Demonstration
