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| Category | Function | Example | | :--- | :--- | :--- | | | Conduct high voltage/current to machinery. | Motors, generators, transformers. | | Control Elements | Low voltage circuits for automation. | Relays, timers, PLC inputs. | | Protection Elements | Safety against overloads and short circuits. | Fuses, circuit breakers, thermal relays. | 4. Essential Industrial Symbols (IEC-based) 4.1 Conductors and Connections | Symbol | Description | | :--- | :--- | | ⎯⎯⎯ | Single conductor / cable. | | ⎯⎯●⎯⎯ | Connection point (junction). | | ⎯⎯✕⎯⎯ | Crossing conductors (not connected). | | ⏚ | Earth ground (chassis or protective ground). | 4.2 Power Supply and Distribution | Symbol | Description | | :--- | :--- | | ⎓ | Direct Current (DC). | | ~ | Alternating Current (AC). | | ⚡ (inside circle) | General power source. | | ⸦⸧ (rectangle with taps) | Three-phase transformer. | | ⎚ | Fuse. | | —⎐— | Circuit breaker (thermal-magnetic). | 4.3 Industrial Loads (Motors and Actuators) | Symbol | Description | | :--- | :--- | | Ⓖ | DC Motor (series/compound). | | Ⓜ (inside circle) | AC Induction Motor (squirrel cage). | | ⎍ | Solenoid valve coil (pneumatic/hydraulic). | | —⎎— | Heating element (resistance). | 4.4 Control Devices (Switches and Relays) | Symbol | Description | | :--- | :--- | | —⎔/— | Normally Open (NO) momentary push button. | | —⎔⎯— | Normally Closed (NC) momentary push button. | | —⏤⎯— | Limit switch (actuated by machine motion). | | —⎎⎯— | Thermal overload relay (NC auxiliary). | | —⎐/— | Relay coil (generic). | | ─┐─┌─ | Relay contact (NO) – delayed closing. | 4.5 Logic and Sensors (Industrial Automation) | Symbol | Description | | :--- | :--- | | —⎕— | Proximity sensor (inductive or capacitive). | | —⌇— | Photoelectric sensor (through-beam). | | —◯— | Pressure switch (closes on high pressure). | | —⌭— | Temperature switch (thermostat). | | & (inside rectangle) | AND logic gate (PLC ladder equivalent). | | ≥1 (inside rectangle) | OR logic gate. | 5. Comparative Table: IEC vs. ANSI Differences Industrial professionals must recognize both. Key differences include: simbologia electrica industrial
| Component | IEC 60617 Symbol | ANSI/NFPA Symbol | | :--- | :--- | :--- | | Resistor | Rectangle | Zigzag line (∧∧∧) | | Coil/Relay | Rectangle with diagonal line | Circle with diagonal line | | Fuse | Rectangle with a line through | Rectangle (simpler) | | Normally Open Contact | ─┐─┌─ | Two parallel lines (||) | Below is a common industrial control circuit using standardized symbols (IEC style): End of Report | Category | Function |
+24V ---⎔/---⎔\---(K1M)---0V (Start) (Stop) (Relay Coil) K1M NO contact --- parallel to Start button (seal-in circuit) | Relays, timers, PLC inputs