Water & Wastewater Instrumentation Solutions Highlights: Pump Control

In Precision Digital’s recently published Water & Wastewater Instrumentation Solutions Guide we show how Precision Digital products have been used to optimize operations in various water & wastewater applications.

The following examples show how Precision Digital’s Helios PD2-6000 and ProVu PD6000 are used for sump level monitoring, pump alternation, and lead-lag pump alternation control applications. Watch the included video of how the pump alternation works with the ProVu. Also, learn how to connect a 2-wire and 3-wire transmitter to the PD6000, and see how the ProVu’s dual-scale feature is displayed on the meter.

Pump Alternation


This pharmaceutical company had a guided wave radar level transmitter measuring the level of wastewater in a sump. Pump alternation was needed to keep the wastewater at safe levels and visual / audible alarm indication was also needed for alerting operators.


A Helios PD2-6000-6H7 with the PDA-LH Light/Horn accessory were installed. The Helios powers the level transmitter, performs pump alternation, and the red light/horn provides high/low level alarm indication. The Helios is especially beneficial for monitoring from far distances because of its large 1.8" (46 mm) digits that are readable from up to 100 feet away.

Lead-Lag Pump Alternation Control: How it Works

Many simple pump control applications do not require the sophistication and complexity of a PLC.

The ProVu PD6000-6R4 pump controller makes a simple and convenient solution for lead-lag pump alternation control with its 4 relays and isolated 24 VDC @ 200 mA transmitter power supply.

Basic Operation

  1. The ProVu pump controller powers up the level transmitter. In this case, the meter displays the level in feet for this 16 foot sump.
  2. Two relays are set up to control and alternate the main and backup pumps.
  3. The other two relays are used for high and low level alarms.

The following diagrams illustrate a typical lead-lag pump alternation control application with high and low alarm monitoring.

Relay #1 turns the main pump on at 8.5 feet and turns it off at 3.5 feet.

With the Pump Alternation feature activated, the next time the level reaches 8.5 feet, relay #2 transfers and starts the backup pump.

If the backup pump is not able to keep up, and the level reaches 10 feet, then relay #1 transfers and starts the main pump as well.

If level continues to rise in the sump, relay #3 trips the High Level Alarm at 11 feet and resets at 10 feet.

If the Main Pump fails to turn off, Relay #4 trips the Low Level Alarm at 2.0 feet to warn against the pump running dry.

Multi-Pump Alternation Video

Powering Up the Transmitter with the ProVu PD6000

One of the most useful features found on the Provu PD6000's line-powered meter is its built-in isolated, 24 VDC power supply to power up the transmitter.

This feature saves money by eliminating the need for an external power supply. Plus, it simplifies wiring by reducing the number of devices in the loop.

2-Wire Connection Diagram

2-Wire Transmitter Connections

3-Wire Connection Diagram

3-Wire Transmitter Connections

ProVu PD6000's Dual-Scale Feature

This unique feature lets you display the measured input in two different ways. Both display lines are scaled independently and are based on the 4-20 mA input signal.

PD6000 Displaying Gallons and Percent Full

Gallons & Percent Full

PD6000 Displaying Gallons and Height

Gallons & Height