Duplex Compressor Alternator Control Panels

UL Listed

UL Listed Duplex air compressor

UL listing assists in acceptance by local codes and regulations.

Panel provides single control source for duplex compressors.

  • Self contained controls include 2 magnetic starters, compressor alternator, on/off switches, and run lights.
  • Power connects to single enclosure.
  • Easy operation via toggle switches & run lights.
  • Alternation features provides even run time of compressor pumps.
  • Automatically starts two compressors when one unit does not keep up with demand.
  • Start/stop operation reduces power usage.
  • Isolation feature allows user to manually turn one compressor off.

Can be field installed on existing duplex or two simplex compressor systems.

Stand Alone Alternator Control Panel

alternator control page (closed)alternator control panel (open)

Shown above left – outside enclosure with toggle switches and run lights.

Shown above right – internal components including two magnetic starters, alternator, wiring and UL label.

The following chart shows the available configurations
Motor Horsepower Phase Voltage
1 ½ – 5 1 230
1 ½ – 5 3 230 or 460
7 ½ 3 230 or 460
10-15 3 230 or 460
20-25 3 460
20-25 3 230
30 3 460
30 3 230

Duplex Compressor Sequence of Operations

  1. The lead pressure switch closes, energizing the alternator relay and 1st air compressor.
  2. The pressure rises opening the lead pressure switch, de-energizing the alternator relay and the 1st air compressor.
  3. The alternator will then alternate from the 1st air compressor to the 2nd air compressor, ready for the next need for compressed air.
  4. The next phase is the same as Steps 1-3, except that the 2nd air compressor will run.
  5. When the need for compressed air becomes greater than the operating compressor can produce and the pressure continues to drop after the lead pressure switch closes, the lag pressure switch will close, starting the 2nd air compressor.
  6. As the pressure rises, the 2nd air compressor will shut off, then the 1st air compressor will shut off.