Northern Foods drives a cool £30,000 plant saving
Northern Foods has saved £30,000 a year in electricity costs, thanks to the installation of three ABB variable speed drives at its Riverside Bakery in Nottingham.
The plant, which produces chilled foods for the likes of Marks & Spencer and Sainsbury, uses large refrigeration units to store both the ingredients and finished products. The refrigeration units are fed by cooling water which is pumped by three 75kW motors.
Soft-start control panels had been used to control the motors since the plant was built 22 years ago. However, as part of its energy saving plan, Northern Foods wanted to find a more efficient way of pumping the water.
Local contractor Inverter Drive Systems (IDS) suggested replacing the existing soft-start control panels with three 55kW ABB industrial drives in control panels. It also supplied a 4-20mA analogue temperature sensor connected to the inverter’s proportional integrated differential controller, which uses the return temperature of the chilled water as its feedback signal.
When the plant is working hard, the requirement for chilled water increases and the pumps run faster. When the plant is less busy at weekends and holidays, the pumps run at minimum speed, as the return temperature of the chilled water is already cool.
Installing the drives turned out to be a challenge as all the plant services, including the chillers, are installed in the roof space. This meant lifting the drives 6m off the production floor through a hatch in the roof. To save space the inverters are side-mounted inside the control panels. The inverters were installed individually, leaving two out of three running at any one time, avoiding lost production time.
Post installation monitoring showed the average power reduction to be about 65% per pump, giving a saving of around £30,000 a year.
Contact: ABB, Tel: 0161 438 3036
