Thursday, 20 February 2014

Steve Hughes, ABB's UK Sales Manager for LV drives writes: It was the headline and then the photo that really caught my attention.

And then the story itself:  Alongside Winne the Pooh, in the sewers of Scotland, was a fax machine, a bike, a snake and jeans.  In fact Scottish Water claims that it dealt with over 40,000 blockages in its drains and sewer network.  It is running an awareness campaign to highlight the issue, which it said creates costs of more than £7m a year.  ABB has an answer tucked away within its ABB drive, the ACQ810, which is dedicated to the water and wastewater industry and it is called anti-ragging or anti-jam.
All water companies experience blockages in the foul pumps, caused largely by rags sticking to the impeller.  As well as downtime, clogging can lead to sewage pollution.  A total system failure can lead to effluent leakage, with implications for the environment and health and safety, as well incurring clean-up costs and resulting in possible breaches of legislation.  Clearing these blockages is an involved and time consuming process.  Every time a pump becomes blocked, it has to be removed from the well, split open and cleaned out, which is an expensive job because a crane has to be hired each time to clean the pump.  To cure this problem,  ABB provides anti-jam software, a function of its ACQ810, variable-speed drive.

The anti-jam software performs a number of cleaning cycles every time the pump starts, each cycle consist of a series of rapid ramp ups in both forward and reverse directions.
Taking one to two minutes to complete, the cleaning cycle removes the debris from around the pump volute, preventing it from entering the pump and blocking it when the pump ramps up from zero to its normal operating speed. One company to benefit is Severn Trent Water (STW). The company is making savings of up to £2,400 a week on pump maintenance after upgrading its pump control software. STW had installed four submersible foul pumps at its sewage treatment works in Worcester, pumping raw sewage from a new foul well. The pumps are driven by four 132kW ABB drives, ACQ810, supplied complete with filters to reduce harmonics caused by the drives.



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