Maintenance fundamentals — full outline

Voltage, current, resistance, AC, DC, single-phase, three-phase, and the why behind 480 V hot-to-hot. Grounding and bonding without the legal padding.

1. 1.1Voltage, Current, Resistance, Power — and How They Show Up on the Floor 22 min10 terms
2. 1.2AC vs DC and Why the Plant Runs on AC 18 min9 terms
3. 1.3Three-Phase Power and Why It Wins for Motors 22 min9 terms
4. 1.4Single-Phase from 480 V, Two Hots, and Why It's Still One Sinusoid 18 min8 terms
5. 1.5Grounding, Bonding, and the System That Keeps You Alive 18 min9 terms
6. 1.6Delta vs Wye, Explained with the Triangle Trig Analogy 14 min9 terms

OSHA 1910.147, NFPA 70E, approach boundaries, the LOTO sequence that keeps you breathing, and the safety habits that separate veterans from victims. PPE specifics are covered separately when the team is ready for that level of detail.

1. 2.1Why Electrical Work Kills, and How LOTO Stops It 20 min10 terms
2. 2.2Arc Flash: What It Is and How NFPA 70E Keeps You Out of It 22 min10 terms
3. 2.3Mechanical and Thermal Hazards on a Production Line 18 min10 terms

The meter is a tool, not magic. What's happening inside when you read volts, ohms, and amps; why true-RMS matters; why input impedance creates phantom voltage; and why ohms mode is really a tiny DC test the meter is running on the circuit.

1. 3.1Inside the Meter — A/D Conversion and True-RMS Math 14 min8 terms
2. 3.2Input Impedance and the Truth About Phantom Voltage 13 min6 terms
3. 3.3Ohms Mode — The Meter Is Sending Out a Test Voltage 14 min7 terms
4. 3.4Voltage Reading Habits — Reference Points and Live-Dead-Live 11 min8 terms
5. 3.5Clamp-On Amp Readings — How the CT in the Jaw Actually Works 11 min6 terms

Three-phase induction motors, across-the-line starters, soft starters, VFDs (the engine of every extruder line), barrel-zone heating circuits with SSRs and contactors, and mechanical vs solid-state relays. The core daily knowledge for a blown-film maintenance crew.

1. 4.1How a Three-Phase Induction Motor Actually Works 22 min9 terms
2. 4.2Across-the-Line Starters and Their Overload Protection 18 min10 terms
3. 4.3Variable-Frequency Drives — The Heart of Every Extruder 25 min9 terms
4. 4.4Mechanical Relays vs Solid-State Relays — Pick the Right Tool 18 min9 terms
5. 4.5Barrel Heating Circuits — The Other Half of the Extruder Line 22 min7 terms
6. 4.6PTC Motor Thermistors and VFD Motor Protection 14 min9 terms

Proximity, photoelectric, ultrasonic, RTD and thermocouple temperature, melt-pressure transducers, load cells, the 4–20 mA loop, and every sensor type a blown-film line uses to know what's going on.

1. 5.1Discrete Sensors: Proximity, Photoeye, and Limit Switches 18 min10 terms
2. 5.2Temperature: RTDs, Thermocouples, and Cold Junctions 20 min9 terms
3. 5.3The 4–20 mA Loop and Analog Signals 18 min8 terms
4. 5.4Melt Pressure, Load Cells, and the Sensors That Make the Line Possible 18 min10 terms
5. 5.50–10 V Analog, Speed Pots, and 2-Wire vs 3-Wire Sensors 14 min9 terms

The science and the wiring behind every barrel zone on the floor: J-type thermocouples and the Seebeck effect, heater bands and their failure modes, solid-state relays and why they read open in ohms, phase-angle vs zero-cross firing, and tuning the PID loop that ties it all together.

1. 6.1J-Type Thermocouples and the Seebeck Effect 14 min8 terms
2. 6.2Heater Bands — Wattage, Amps, and How They Fail 11 min8 terms
3. 6.3Solid-State Relays — Zero-Cross and Why Ohms Reads Open 14 min8 terms
4. 6.4SSR Control Modes — Phase-Angle vs Burst-Fire 13 min7 terms
5. 6.5PID Loops — Tuning a Barrel Zone Without Hunting 12 min9 terms

How resin gets from the silo or gaylord to the extruder throat: vacuum pumps, receivers, filters, the continuous-run valves that keep PD pumps alive, airlocks for solids handling, and the PM schedule that prevents downtime.

1. 7.1Vacuum Conveying Basics — Pumps, Receivers, Sequencers 12 min9 terms
2. 7.2Continuous-Run Valves — Keeping a PD Pump Alive 12 min8 terms
3. 7.3Airlocks and Rotary Valves — Pellet Handling and Dust Collection 11 min8 terms
4. 7.4Filters and the Conveying PM 10 min10 terms

The half-split method, signal tracing, true voltmeter technique, clamp meter use, finding intermittents, and the systematic mindset that separates a maintenance pro from a parts-changer.

1. 8.1The Troubleshooting Mindset and the Half-Split Method 18 min8 terms
2. 8.2Voltmeter Technique That Actually Works 22 min8 terms
3. 8.3Clamp Meters and Diagnostics 17 min8 terms
4. 8.4Finding the Hard Stuff: Intermittents, Phantoms, and Weird Failures 17 min8 terms
5. 8.5Open Neutrals and E-Stop NC Fail-Safe Circuits 14 min8 terms

Why blown film needs corona treatment to take ink or glue, how a Pillar-style treater actually works (HF generator, ceramic roller, film as part of the load), and the speed-sensor interlocks that prevent a stopped web from destroying the equipment.

1. 9.1Why Corona Treatment Exists — Dyne Level and Surface Energy 9 min8 terms
2. 9.2How a Pillar Treater Works — Generator, Transformer, Electrode, Ceramic Roller 14 min8 terms
3. 9.3Roller Speed Sensor Interlock — Why Stopped Film Means Shutdown 11 min8 terms
4. 9.4PM and Troubleshooting — Ceramic, Electrode, Ozone, Generator Faults 11 min8 terms

How load-cell-based batch blenders dose virgin, color, and additive by weight; the hardware, the math, the calibration, and the failure modes that show up at the extruder throat.

1. 10.1Gravimetric vs Volumetric — Why Weight Wins for Blends 12 min10 terms
2. 10.2The Hardware — Load Cells, Weigh Hopper, Valves, Mixer 13 min9 terms
3. 10.3Recipes, Calibration, and the Throughput Calculation 12 min10 terms