Failure of screw air compressors to start is a high-frequency fault in industrial settings, directly causing compressed air supply interruptions and disrupting normal production line operations. This fault stems from multiple dimensions, including electrical systems, control systems, and mechanical components, requiring systematic troubleshooting following the principle of "from simple to complex, from electrical to mechanical." Drawing on frontline maintenance experience, this article breaks down root causes and provides actionable troubleshooting steps to guide technicians.  

Step 1: Inspect the Power Supply System to Ensure Normal Power Input  

Power anomalies are the most fundamental cause of failure to start and must be prioritized. First, check if the compressor’s main power switch and emergency stop button are reset—if the emergency stop button is not twisted out, the unit will remain in a power-off protection state. Next, use a multimeter to measure three-phase voltage, ensuring it falls within ±5% of the equipment’s rated voltage; excessive or insufficient voltage triggers electrical protection, preventing startup.同时, inspect power cables for looseness, short circuits, or overheating, and check for oxidized or poorly connected terminals (tighten terminals and clean oxidation layers if needed). Additionally, verify if fuses or residual current protectors in the distribution cabinet have tripped—if tripped, investigate overload or short-circuit causes before resetting.  

Step 2: Inspect the Control System to Ensure Normal Transmission of Start Commands  

After confirming normal power supply, verify if the control system issues start commands. First, observe the control panel’s display: if there is no display, the panel’s power module may be faulty or communication lines loose—check panel power connectors and replace damaged modules. If the panel displays normally but the start button has no response, access the parameter interface to check if "remote control" mode is enabled; local start buttons are disabled in remote control mode, requiring a switch to local mode. Then, inspect the PLC controller: use a multimeter to test if the input point corresponding to the start button receives signals (a lack of signal may indicate a damaged button or broken line). If input signals are normal but no output signals are sent, further check for PLC program anomalies or replace faulty PLC modules.  

Step 3: Inspect Protection Devices to Confirm No Fault Interlock Activation  

Screw air compressors are equipped with multiple protection devices; activation of any protection triggers a startup block. First, check fault codes on the control panel—common protection faults include low oil level protection (insufficient lubricating oil), high temperature protection (oil temperature not cooling to normal range after shutdown), and high pressure protection (unreleased discharge line pressure). If oil level is below the scale, add dedicated lubricating oil; if oil temperature is too high, wait for it to drop below 40℃ before restarting; if discharge line pressure is too high, open the vent valve to release pressure. Additionally, check if motor overload protectors, belt breakage protectors (for belt-driven compressors), or oil-gas separator differential pressure protectors are activated—reset fault codes on the control panel after clearing faults to enable normal startup.  

Step 4: Inspect Mechanical Components to Confirm No Seizure or Jamming  

If no anomalies are found in the first three steps, inspect mechanical components for jamming. First, cut off power and manually rotate the compressor coupling: if rotation is difficult or impossible, the main rotor may be seized due to oil shortage, carbon buildup, or foreign object intrusion, or the motor bearings may be damaged. In this case, disassemble the main unit end cover to inspect rotor wear, clean carbon buildup and foreign objects, and replace damaged bearings and seals. If rotation is smooth, check the motor for faults: use a megohmmeter to measure motor insulation resistance—if resistance is below 0.5MΩ, the windings are damp or burned, requiring drying or motor replacement.  

After completing troubleshooting, closely monitor parameters such as pressure, temperature, and current during test runs to ensure no anomalies before putting the unit into normal operation. In daily maintenance, regularly inspect power lines, clean control panels, and maintain sufficient lubricating oil to effectively reduce the incidence of startup failures.