자주 묻는 질문
자주 묻는 질문
What is a PLC? Types and Applications of PLCs
PLC, also known as a Programmable Logic Controller, uses a type of programmable memory to internally store programs that execute user-oriented instructions such as logic operations, sequence control, timing, counting, and arithmetic operations. It controls various types of machinery or production processes through digital or analog input/output.
Initial Operating Data
A control program always requires initial data. This data can be obtained in several ways:
- From External Devices: Initial data can be acquired from devices connected to input ports, using transfer instructions to read the data and send it to internal units.
- From the Program Itself: Immediate values can be transferred to internal units through the program.
- Machine Internal Data: Some operational data stored in specific locations within the machine can be sent to the working unit through an initialization program at startup.
Types of PLCs
Commonly used PLCs in China include Siemens, Schneider, Mitsubishi Electric, Panasonic, Delta, and domestic brands. Below is a summary of major PLC brands:
1. Delta PLC
- Designed by Delta Group for industrial automation.
- Uses programmable memory for logic operations, sequence operations, timing, counting, arithmetic operations.
- Controls machinery or production processes through digital or analog inputs/outputs.
2. Siemens PLC
- Widely used in metallurgy, chemical industry, printing lines.
- Historical progression: SIMATIC S3 → S5 → U-series → S7 series (from 1975 to 1994).
- PCS7 concept proposed for process control in 1996.
3. Schneider PLC
- Includes Quantum, Compact (discontinued), Momentum, Premium, Micro, Twido, and ZelioLogic series.
- Programming software: Concept, PL7Pro, UnityPro, TwidoSoft/ZelioSoft.
4. Mitsubishi Electric PLC
- Main models: FR-FX1N, FR-FX1S, FR-FX2N, FR-FX3U, FR-FX2NC, FR-A, FR-Q.
- Supports logic operations, sequence control, timing, counting, arithmetic operations.
5. Rockwell PLC
- Includes large, medium, micro & nano, and safety PLCs.
- Programming software: RSLogix, RSLogix5, RSLogix500, RSLogix5000.
6. Panasonic PLC
- Available since 1981.
- Series: FP-XH, FP7, FP-X0, FP0R, FP-e, FP-X, FPΣ, FP2SH, FP0.
- FP-XH features fast instruction processing, flexible expansion, high-speed pulse output.
7. ABB PLC
- Controllers: AC800F, AC800M, AC700F, AC500, AC500-eco.
- Supports fieldbus interfaces, controller redundancy, communication and power redundancy.
8. Fatek PLC
- Founded in Taiwan, 1992.
- Focus on high-performance small and medium-sized PLCs.
9. Hollysys PLC
- Products: LM small PLC, LK large PLC, MC series motion controllers.
- Certified with CE and UL; widely used in subways, mines, oil fields, water treatment, machinery.
Applications of PLCs
PLCs are widely used in steel, petroleum, chemical, electric power, building materials, machinery, automotive, textile, transportation, environmental protection, and entertainment industries.
1. Logic Control of Digital Signals
- Replaces traditional relay circuits.
- Used for single or multiple machine control and automated production lines (e.g., injection molding, printing, stapling, grinding, packaging, electroplating).
2. Analog Control
- Handles continuously changing quantities: temperature, pressure, flow, liquid level, speed.
- Uses A/D and D/A conversion modules for analog signals.
3. Motion Control
- Controls rotary or linear motion via digital I/O or dedicated motion control modules.
- Drives stepper or servo motors; widely applied in machinery, robots, elevators.
4. Process Control
- Closed-loop control of analog quantities (temperature, pressure, flow).
- Uses PID adjustments; widely applied in metallurgy, chemical industry, heat treatment, boilers.
5. Data Processing
- Supports mathematical operations, data transfer, conversion, sorting, table lookup, bit manipulation.
- Enables data collection, analysis, comparison with reference values, transmission to other intelligent devices, or printing.
6. Communication and Networking
Modern PLCs include convenient network interfaces for factory automation networks.
Communication between PLCs and other intelligent devices.
Fresh Air System – Unidirectional Duct Fan FAQs
Precautions for Use
- Turn off the power during installation or maintenance.
- Do not install the duct fan in locations where the temperature exceeds 40°C.
- The installation height of the duct fan must be above 2.3 meters to reduce the risk of injury.
- Installation work must be carried out by professionals.
- When installed in bathrooms or similar locations, a qualified residual current circuit breaker must be added.
- Do not place the switch within reach inside the bathroom.
- Indoor wiring must include a device that disconnects all poles of the power supply.
- Do not install in areas accessible to open flames.
- Prevent gas from backflowing from gas pipelines or combustion appliance ducts into the room.
- Only use for general exhaust; do not use for discharging hazardous or explosive gases.
- Do not use above cooking areas, or in places with excessive oil smoke or high humidity (see Figure A).
- Do not install in locations with steam.
- Install securely to avoid abnormal noise.
- Provide a proper air intake opening.
- Install an inspection port.
- This product must be grounded.
- The unit casing should not touch other objects.
Troubleshooting
| Problem | Possible Cause | Troubleshooting |
|---|---|---|
| Low airflow | Low voltage, poor duct, clogged filter | Check voltage, duct connections, clean or replace filter |
| Vibration/noise | Product touching other objects, obstructed duct | Inspect exterior and duct for foreign objects |
| Abnormal operation | Wrong wiring | Correct the wiring |
Abnormal phenomena, possible causes, and corresponding corrective actions: (Refer to table)
Maintenance and Care
After cleaning, reinstall the filter in its original direction and replace the inspection cover. When installing a new filter, remove the packaging before installing it into the unit.
Before cleaning or maintenance, turn off the operating switch and the dedicated circuit breaker.
Do not allow water to enter the motor.
Do not use gasoline, benzene, thinner, or similar chemicals to wipe the unit.
The primary filter should be cleaned regularly according to the usage environment and time; it is recommended to clean at least once a month. Adjust the maintenance cycle based on local conditions. Use a vacuum cleaner for cleaning; do not wash with water or clean with volatile oils or metal brushes. Protect your eyes during cleaning.
The PM2.5 filter is recommended to be replaced every 6–12 months. If the side indicated by the arrow becomes black, replace the PM2.5 filter promptly.
Purchase filters through authorized dealers.
Fresh Air System – Choosing a Fresh Air or Heat Recovery Unit
Choose the Type of Heat Recovery Unit According to Interior Design
Select the type of heat recovery unit based on the interior design. If planned at the early stage of decoration, a ceiling-mounted heat recovery unit can be integrated with the room structure. Ceiling-mounted units are usually installed within the ceiling; choosing a smaller, thinner model can maximize usable space after renovation.
Consider Budget and Costs
If you only need to bring in and filter outdoor air, a unidirectional duct supply fan may suffice. If higher indoor air quality is desired along with energy-saving and eco-friendly considerations, a heat recovery unit is recommended.
How to Choose the Right Model
Select the required airflow based on the building area (m²) and number of rooms. For heat recovery units, first determine the necessary ventilation volume according to the room size. Choosing too high a ventilation rate will increase air-conditioning costs, while too low a rate will reduce air replacement efficiency. Generally, an indoor air exchange rate of 1 time per hour is recommended. For example, a 99 m² room with a 2.5 m ceiling requires a unit with an airflow of 250 CMH (m³/h).
Filter Replacement and Filter Grades
A key function of fresh air and heat recovery units is circulating indoor and outdoor air, improving indoor oxygen levels for a more comfortable environment. However, with outdoor air pollution and high PM2.5 concentrations, filters are critical. Heat recovery units should include both primary filters and HEPA antibacterial filters. Primary filters capture dust, sand, and pollen, while HEPA antibacterial filters remove PM2.5 particles. Units with activated carbon filters can also reduce volatile gases and odors.
Electricity Consumption
Fresh air and heat recovery units need to operate continuously to maintain indoor air quality. It is recommended to choose models with DC inverter motors, which consume only about half the electricity of traditional AC motors, resulting in significant savings over long-term operation.
Bathroom Heater – Delta Bath Heater FAQs
Winter is here—do you feel a chill every time you wash or get ready in the bathroom?
To create a comfortable bathroom experience during the cold season, consider the Delta Bath Heater!
Bath heaters have become increasingly popular in recent years as bathroom ventilation and heating devices, especially suitable for new bathroom renovations. When cold winter air hits, stepping into a chilly bathroom can be uncomfortable. Turning on a bath heater before bathing quickly warms the space, and after bathing, it prevents discomfort caused by sudden temperature changes. Bath heaters are especially appreciated in homes with newborns or elderly family members, giving your loved ones a five-star level of comfort.
1. Can a bath heater only be used in winter? How do the “cool/warm” and “dry” functions differ?
Delta bath heaters feature not only warm air but also cool air, drying (cool/warm), and ventilation functions.
- Cool air: In summer, the cool air function circulates the bathroom air like a gentle fan, relieving heat and humidity.
- Drying vs. Warm air: The drying function differs from the warm air function. Warm air heats indoor air via a PTC ceramic heater (recirculating indoor air without exhausting it outside). The drying function, besides heating the air, also opens the exhaust duct, removing indoor moisture to leave the bathroom dry and fresh.
- Ventilation: Essential year-round, ventilation works like a standard exhaust fan, removing odors and keeping the bathroom environment clean.
2. Recommended Bath Heater Installation Position
Install the unit in the center of the bathroom with the warm air outlet directed toward the dressing area (dry zone). Avoid placing it directly above the shower or bathtub (wet zone) to prevent wind chill during showers.
3. Installation Precautions
Key Points to Note When Installing a Bath Heater:
A. Do not install the unit in locations where the temperature exceeds 40°C.
B. Recommended installation height is 2.3–2.5 meters to reduce injury risk.
C. When installed in humid areas like bathrooms, always add a residual current circuit breaker (RCCB) with leakage current below 30mA.
D. Use a dedicated, independent power circuit.
E. Install a “full-pole power switch” with a contact gap ≥3mm in the supply line to control the main power; rated load ≥250V/20A, and place it outside the bathroom for easy access.
F. Do not install in areas accessible to open flames.
G. Install an external exhaust hood to prevent birds or rainwater from entering the duct.
H. For high-rise or windy areas, consider installing a backdraft damper to reduce noise from improper exhaust flow.