Controller puts an end to pumping station's ragging woes

Utility company Severn Trent had a significant problem with ragging in a sewage pumping station (SPS), which caused repeated pump tripping and demanded regular pump lift and clean operations,

The station, which lies in a village on the Nottinghamshire/Leicestershire border, is a terminal pumping station, receiving from three other pumping stations in the village and pumping to the local treatment works, a kilometer away.

In addition, the site – which was 30 minutes’ drive from the nearest engineering base – caused frequent telemetry alarms requiring a 4-hour response.

Operators and technicians were responding to calls at all hours to reset tripped pumps and there was the possibility of OFWAT outcome delivery incentive penalties. Staff responding to out of hours callouts were then unavailable the following working day, meaning that programmed work had to be rescheduled.

Technicians were responding to calls at all hours to reset tripped pumps and there was the possibility of outcome delivery incentive penalties

Control systems provider CEMA Automation was the framework panel builder. Framework manager Chris Hutchinson attended site and subsequently chaired a meeting with all stakeholders.

Said Hutchinson: “It became clear to us that the issue was in the chamber design, causing the pumps to rag up excessively, tripping the pump starters.” The pumps were being lifted and cleaned as often as once a month.

 “The normal solution to the issue would have been to install variable speed drives, but in this case there was no room, a new cabinet would have had to have been supplied.

“I had attended a seminar at Pulsar and I knew that their Ultimate Controller offered a pump reversing feature as an optional extra.”

Pulsar Process Measurement Ltd worked with Cema to supply automatic pump reversing technology delivered through the high specification Pulsar Ultimate Controller. The product also logs site data, provides all necessary control functionality for the well and there was no need to modify the existing compact cabinet or replace drive units on the pumps.

A compact control system that also incorporates Pulsar’s Datem level control software, it offers the user a choice between non-contacting ultrasonic or Radar measurement (in this case ultrasonic).

The controller is designed to offer sophisticated control of the pumping station, including an in-built WITS compliant telemetry outstation and even the option of a camera. Pump power usage is monitored by optional Power Monitor modules mounted in the starter section, which in this case included proprietary Retroflo software that automatically detects load and reverses the pumps to clear ragging.

Since the installation of the Pulsar equipment last year, there have been no further unforeseen maintenance requirements on the pumps.

Zac Dorn, the technician responsible for the site, said:

“Each lift and clean operation required a couple of operators and a couple of hours, and it meant that planned work went out of the window. I’m really pleased with the Ultimate system.

The data logs are also invaluable, we can immediately see how many times the Retroflo has reversed the pumps, we don’t need a PLC to manage the station and we can rely on the equipment to perform.”