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PDC: Duplex Pump Down Controller with High Alarm


• Pump Down


• De-Bounced Inputs


• High Alarm Output


• Lost Input Compensation


• Removable Terminal



• Low Level Cut-Off


• Staggered Starting


• Indicating LEDs


• Manual or Auto Alarm



• Float Sequence Error



The PDC has been designed to operate as an alternating Duplex Pump Down Controller with high alarm. The PDC also has the capability of sensing one or two damaged float switches and adjusting its operation accordingly.


When the level rises above the “Cut-Off” float, the input closes to the PDC, the LED is illuminated, but no pump outputs are initiated. As the level continues to rise above the “Lead” float, the LED is illuminated and the output contact to start pump #1 is closed. If the level begins to lower below the “Lead” float, the “Lead” float LED goes out, but pump #1 continues to run until the “Cut-Off” float opens. This is the end of a pumping cycle.


Since a pumping cycle has been completed, the PDC will automatically switch the lead pump to pump #2 (Alternating Operation). This provides for distributed running time on both pumps, helps to ensure that the impellers are cleared periodically and the seals are wetted, extending the life of the pump.


Next time the “Lead” float closes, the pump #2 comes on first. If the level continues to rise and the “Lag” float is closed, then pump #1’s output contacts will be closed too. Both pumps will be running at this time. As the level clears the “Lag” and “Lead” floats, the appropriate LEDs will go out, but both pumps continue to run until the “Cut-Off” float is cleared. This ends the pumping cycle and the lead and lag positions of the pumps switches again.


To avoid pulsing the pump motors On and Off due to turbulance in the tank, when a “Lead’ or “Lag” float switch closes, it latches in until the “Cut-Off” float opens. If both “Lead” and “Lag” float switches are closed when power is applied to the PDC, there will be a 5 sec. time delay to start the first pump and another 5 sec. delay to start the second pump. This avoids high inrush levels during recovery from a power outage.


(download pdf spec sheet at left for more operation details)




Line Voltage:

     24V AC/DC, ±10%

     115 or 230VAC, ±10%, 1Ø, 50/60Hz

Inputs: Normally Open (NO) contact or Solid State (NPN)

Power Up Delay: 5 Sec., Fixed

Second PumpDelay: 5 Sec., Fixed

Contact Ratings:

     10 Amps Total Unit Rating

     5 Amps @ 240VAC, per contact

     10 Amps @ 120VAC, per contact

     100,000 Full Load Electrical Cycles

     10,000,000 Mechanical Cycles



Mounting: Surface

Termination: Screw Terminals Removable (Plug-In)

Packaging: Dust Cover

Weight: 2 Lbs. Approx.


Ambient Temperatures

Operating: 0°C to 65°C

Storage: -30°C to 85°C


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