Industrial Engineer · phase 2 of 16
Isolation
Electrical separation that limits unwanted current paths between field circuits, channels, and controller electronics.
The Explain card
- Plain English
- Isolation is an electrical barrier that keeps one circuit's current from finding a path through another. Optocouplers and transformers pass the signal without connecting the wires.
- Example
- An isolated input card lets a sensor on a 120 VAC circuit talk to a controller running on 5 V logic. A fault on the field side stays on the field side.
- Why it matters
- Without isolation, a ground loop between two panels can shift readings, and a wiring fault can put line voltage on the backplane. Channel to channel isolation is also what lets one card read signals referenced to different commons.
- Hook
- The signal crosses, the current stays home.
Where it sits in the deck
Phase 2: PLC I/O and Field Signals
Where the controller meets the machine: discrete and analog signals, the wiring conventions behind them, and the field devices that send them.
