Case Study 7 - Severn Trent Anti-Ragging Software Saves Thousands

abb's anti ragging software frees up wastewater pumps

A case of rags to riches with Severn Trent Water saving 2,4k a week with ABB's anti-ragging software. Watch the video here: ABB's anti-ragging software for water drives

Getting rid of wet wipes and toilet paper substitutes has left a water authority flushed with success. Severn Trent Water had been experiencing severe problems with blockages on four foul pumps (controlled by four ABB, 132kW drives) caused by rags sticking to the impellers. On average the blockages were so severe that they had to be cleaned every two days. The expense and labour involved were considerable. When a pump became blocked it had to be removed from the well, split open and cleaned out. This was not a popular job - and required the hire of a crane.

The clogging was pointed out during an ABB engineer's visit to site and he suggested that ABB's anti-ragging software could be a remedy to the ongoing problem. As variable speed drives were already being used for speed control, the anti-ragging software could be installed on them (the software is standard on ABB's ACQ580 water drives) and effectively 'shakes off' the rags during ramp up.

Anti-jam software is a module of ABB's 'Intelligent Pump Control' software and allows a number of cleaning cycles at pump start up. This consists of a series of rapid ramp ups in both forward and reverse, performed without stressing the motor. On average, it takes around two minutes to complete, and when finished the debris from around the pump volute will have been removed, preventing it from entering the pump and blocking it when the pump ramps up from zero to its normal operating speed. The beauty of anti-ragging software is that it will also 'kick-in' if it detects a drop in pump efficiency.

The benefits? No pumps have clogged since the software was fitted: a true rags to riches story.