TL;DR
Read the Elektronikon fault code first. Most won't-start faults are a pressure switch error, VSD input fault, or supply voltage issue. Fault code lookup takes 2 minutes and narrows the field immediately.
What you might see
- no response when start button pressed
- fault code on Elektronikon display
- main contactor does not close
- VSD trips immediately on start command
Likely causes
Pressure switch failure or setpoint drift, making the controller believe system pressure is already at or above cut-out
VSD input fault from supply voltage imbalance, blown fuse, or loose input terminal
Emergency stop circuit open, latched E-stop or remote interlock not reset
Elektronikon controller fault requiring reset after a prior high-temperature or overcurrent shutdown
Required tools
- Multimeter rated for supply voltage
- Clamp ammeter
- Elektronikon controller (fault log access)
- LOTO kit
- Replacement fuses (correct rating per schematic)
Safety first
- Voltage measurements on energized panels require arc-flash-rated PPE and an Energized Electrical Work Permit.
- VFDs retain a lethal DC bus charge after main disconnect. Wait at least 5 minutes before opening the VSD enclosure.
Procedure
- 1
Read the active fault code on the Elektronikon display. Record the exact fault text.[1]
- 2
Check if an emergency stop is latched anywhere in the system. Reset all E-stops and confirm remote interlocks are closed.
- 3
Verify supply voltage at the main isolator with a multimeter. Check all three phases. Voltage outside the nameplate range or imbalance above 2% prevents start.
- 4
Open the control panel and check the main fuses. Replace any blown fuse with an identical rating.
- 5
Press the fault reset button on the Elektronikon and attempt a restart. If the same fault returns immediately, the underlying condition is still present.[1]
- 6
Locate the pressure sensor and check its reading on the controller. If the sensor reads above cut-out when system pressure is actually low, replace the pressure transducer.
- 7
If the VSD trips with an input fault, measure each phase current at the drive input terminals while attempting start. Imbalance or loss of one phase will cause the trip.
Sources
Atlas Copco GA VSD+ Air Compressor User Manual, Atlas Copco
Atlas Copco GA VSD+ IOM, Elektronikon fault code list and start-up diagnostic procedures (general)
View source
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