Common components for electricians and PLC

The following are the common components and their functional classifications in the fields of electrical work and PLC (Programmable Logic Controller):

 I. Common Components for Electricians

1. Switches and Protection Devices

- **Circuit Breaker**: Protects against overload and short - circuit (e.g., 16A/20A single - pole circuit breakers for household use).

- **Ground Fault Circuit Interrupter (GFCI)**: Detects electrical leakage and cuts off the power supply (commonly used in socket circuits).

- **Contactor**: Controls high - current circuits with low - current signals (e.g., for starting and stopping motors).

- **Relay**: Converts weak - current signals to control high - current circuits (e.g., time relays, intermediate relays).

 2. Power Distribution and Control Components

- **Fuse**: Protects against over - current (e.g., porcelain plug fuses, screw - in fuses).

- **Transformer**: Converts current or voltage (e.g., Current Transformer (CT), Potential Transformer (PT)).

- **Terminal Block**: Connects wires (e.g., rail - mounted terminals).

- **Distribution Box/Cabinet**: Centralizes the installation of components (e.g., household distribution boxes, industrial control cabinets).

3. Motors and Drives

- **Motor Starter**: Enables direct starting or star - delta starting (e.g., products from ABB, Siemens).

- **Frequency Inverter**: Controls the speed of motors (e.g., Variable Frequency Drive (VFD) for energy - saving in fans and pumps).

- **Soft Starter**: Smoothly starts large motors, reducing inrush current.

 4. Other Components

- **Cables and Wires**: Selected according to current - carrying capacity (e.g., THHN copper wires).

- **Buttons and Indicators**: Used for operation and status display (e.g., emergency stop buttons, power indicators).

 II. Common Components for PLCs

 1. PLC Main Unit

- **CPU Module**: The core computing unit (e.g., Siemens S7 - 1200, Mitsubishi FX5U).

- **Power Supply Module**: Provides stable voltage (usually DC 24V).

 2. Input/Output (I/O) Modules

- **Digital Input (DI)**: Receives switch signals (e.g., from buttons, limit switches).

- **Digital Output (DO)**: Controls contactors and solenoid valves.

- **Analog Input (AI)**: Handles continuous signals such as temperature and pressure (e.g., 4 - 20mA).

- **Analog Output (AO)**: Adjusts frequency inverters and control valves.

 3. Sensors and Actuators

- **Sensors**: Proximity switches, photoelectric sensors, temperature transmitters.

- **Actuators**: Cylinders, servo motors, control valves.

 4. Communication and Expansion

- **Communication Module**: RS485, Ethernet/IP, Profibus.

- **Expansion Module**: For high - speed counting, positioning control (e.g., Siemens SM 1231).

 5. Programming and Human - Machine Interface

- **Programming Software**: TIA Portal (Siemens), GX Works3 (Mitsubishi).

- **HMI (Human - Machine Interface)**: Touch screens (e.g., Weintek, Siemens TP series).

 III. Typical Application Scenarios

1. **Industrial Automation**: PLCs control production lines and robots.

2. **Building Control**: HVAC (Heating, Ventilation, and Air Conditioning) systems and lighting systems.

3. **Water Treatment**: Logical control of water pumps and valves.

4. **Traffic Signals**: Timing control of traffic lights and barrier gates.

 IV. Selection and Precautions

- **Electrical Components**: Select based on voltage, current, and environment (e.g., waterproof, explosion - proof).

- **PLC Systems**: Calculate the number of I/O points, response speed, and storage capacity.

- **Compatibility**: Ensure that the communication protocols of the PLC, sensors, and frequency inverters are compatible.

Summary

- **Electrical components** focus on high - power control and power distribution safety.

- **PLC components** focus on logical operations and automation integration.

If you need specific model recommendations or circuit design examples, please further describe the scenario!