The DC motors were employed on Whitehead & Poole piston ram pumps that are used to transfer sludge from the Laighpark waste water treatment site, which serves around 150,000 people in the Paisley area of Glasgow, to Shieldhall waste water treatment plant. They had been installed for some years, providing the high torque at start-up necessary for the pumping operation, and the facility for variable speed control of the pumps via a simple potentiometer.
Because the capacity for storing sludge at Laighpark is limited, transfers to Shieldhall are made daily. This places a premium on the reliability of the two front line motors – the third is a duty stand-by - which are generally called upon to operate for 6-hours a day. This was not a problem until recently, when the age of the motors starting causing concern. Apart from questions of ongoing motor reliability, spares were becoming a particular problem, especially so in view of the repeated failures of the DC control equipment that were being experienced.
In view of the frequent failures, the Operations Team Leader, Willie Lindsay, submitted a request for the E&M technical support to investigate. It was determined, subsequently, that all three of the DC machines would have to be replaced in order to restore higher levels of reliability to the sludge pumping operation. For the supply of the replacement motors, Scottish Water turned to Brammer, with whom it has a framework agreement. This agreement means that Brammer actively works on Scottish Water’s behalf to deliver the most cost effective, reliable and suitable products across a wide range of categories, including gearboxes, motors, inverters, power transmission, bearings seals, lubricants and many other products.
“Scottish Water was looking for a solution that delivered the flexibility to control the pumps in the manner that they always had,” said Walter Bryce of Brammer. “However, these benefits had to be delivered in a package that offered the best competitive price and the longest possible warranty. Following consultations with Tony Leslie and David Doig, both Technical Support Advisors, we were able to deliver all these benefits with a matched motor and inverter drive package from WEG.”
“Brammer offered us the best package in terms of price, warranty and technical back-up, with the WEG motors and drives,” said Tony Leslie. “The three-year guarantee that WEG has provided on the combined motor-inverter package provides us with greater security of purchase and a single source responsibility for the equipment, which is vital in a continuous process industry, should problems arise.”
“The fact that we can offer such a comprehensive warranty is evidence of the confidence we have in the quality and reliability of our equipment,” said Marek Lukaszczyk, European Marketing Manager for WEG. “This is the result of WEG’s unique policy of manufacturing all of its own components and equipment, right down to the wire and resins used in our electric motors; it’s a policy we intend to continue.”
The motor drive package provides improved flexibility in the operation of the pumps. It comprises 3- W21 200kW EFF1 high efficiency motors, and 3- CFW-09 frequency inverters. The motors are effectively matched with the drives because this has consistently demonstrated the highest levels of energy saving – and reliability.
Brammer supplied the motors, drives and control gear to a local panel builder (Aird Walker & Ralston Elec Engs) in Kilmarnock. The drives and control gear were built into control cubicles and then installed on site. An engineer from WEG subsequently visited the Laighpark site to assist in the commissioning of the project, which was completed in a day, minimising any disruption at the facility.
xCommenting upon the installation, Tony Leslie said: “We have been impressed by the high level of technical support provided by Brammer and by WEG throughout the project and by the excellent after sales service we received following the installation. The products have proved to be totally reliable, which vindicates our decision to use WEG motors and drives for the first time."