Screw air compressors are essential components in modern industrial production. Their efficient and stable operation relies heavily on sophisticated control systems that ensure protection, automation, and optimized energy consumption. This article outlines the key control measures, characteristics of single and centralized control systems, inverter selection tips, and best practices for energy-saving monitoring.
1. Types of Protection Control Systems in Screw Air Compressors
Screw compressors typically use two types of control systems:
- Single Compressor Protection Control: Each compressor has its own controller that manages protection and operation.
- Centralized/Linked Control System: Multiple compressors share a centralized control cabinet that can integrate with a DCS system in the control room. It handles master-slave switching, automatic start/stop sequences, and balanced operating time distribution among units.
2. Features of Single-Unit Control Systems
Single screw compressor controllers use IC boards or microprocessor-based panels. They provide real-time control and monitoring, including:
- Automatic control of shutdown, standby, start-up, load/unload, emergency stop
- Real-time monitoring of exhaust pressure and temperature
- Filter replacement alerts based on runtime
- Software upgradeability for various industrial applications
- Simple interface and user-friendly operation
3. Central Control Cabinet Functions
Key functions of centralized (linked) control include:
- Staggered Startup: Compressors start sequentially with a 20-second interval.
- Load/Unload Automation: Compressors stop automatically when pressure exceeds set limits.
- Parameter Configuration: Users can adjust high/low pressure limits, switch intervals, start/stop delays, and unit prioritization.
- Fault Handling: Faulted units are automatically removed from the system while the rest continue operation.
- Operating Time Balancing: The system alternates main and standby units for even runtime.
- Flexible Control Assignment: Compressors can be manually removed or added back into the linked system.
- Signal Communication: Linked systems send signals such as operation status, idle alerts, critical faults, and start permissions to central control rooms.
4. Switching Between Single and Centralized Control
Key precautions include:
- Use selector switches to toggle between linked or standalone mode.
- Compressors must be reactivated manually when switching to centralized mode.
- In case of major fault, isolate and repair the unit before reintroducing it to the linked system.
5. VFD (Inverter) Selection Tips
When choosing inverters, consider load types:
- Fans and Pumps: Match inverter capacity with motor capacity.
- Cranes and Hoists: Allow extra capacity for startup shocks and regenerative energy.
- High Inertia Loads: Use slightly oversized inverters and braking units.
- Uneven Loads: Size inverters based on the maximum load condition.
Additional Notes:
- For low-speed operation, increase the gear ratio or use 6-pole motors.
- Limit cable length to 50m or use output reactors for longer distances.
6. Energy Monitoring Requirements
To effectively monitor compressor energy consumption:
- Conduct tests under normal, stable operating conditions.
- For stable loads: use a 2-hour sampling period; for variable loads, cover full load cycles.
- Sample all parameters (pressure, temperature, flow, power) simultaneously and at least three times.
- Use flow meters or heat balance methods for volume flow measurement.
- Ensure instruments are within calibration and accuracy limits.
Заключение
Effective protection and control of screw air compressors ensure reliable performance, energy efficiency, and long-term savings. By leveraging advanced control systems and regularly monitoring energy use, industries can optimize their compressed air systems and reduce downtime.
For more technical guides, visit our Air Compressor Knowledge Hub.
Need help configuring your control system? Contact Baldor’s technical support for expert assistance.