The Problem

Brintons Carpets, one of the UK’s leading carpet manufacturers, needed to review is production processes as all of their spinning frames were DC controlled. The existing DC motors were obsolete and Brintons had difficulty in obtaining spares. The 75 kW motors needed regular maintenance with each one requiring 12 carbon brushes to be exchanged every year. The annual cost to the plant for replacement parts is about £5,000 per annum not including the cost of manpower.

Sentridge’s Solution

Sentridge has a long working relationship with Brintons having provided them with variable-speed drives and technical back up for many years. Phil Tomkinson, Sentridge’s Area Manager, visited the manufacturer’s plant to assess the production processes and evaluate how best Brintons could not only reduce maintenance costs but also energy consumption.

Sentridge initially ran a trial on site using an early generation ABB industrial drive and revealed 19 percent energy savings, equating to 0.5 MW per year. Since the trial, ABB has introduced a more efficient drive, the ACS880, that features 4th generation motor control platform, DTC, and the energy savings are even greater, totalling some 504,000 kWh saved. Together with the installation of IE3 ABB motors, return on investment was expected within three years but when the Government’s Enhanced Capital Allowance is factored in payback drops to 2.6 years.

The Full Story

Brintons Carpets, one of the UK’s leading carpet manufacturers, needed to review is production processes as all of their spinning frames were DC controlled. The existing DC motors were obsolete and Brintons had difficulty in obtaining spares. The 75 kW motors needed regular maintenance with each one requiring 12 carbon brushes to be exchanged every year. The annual cost to the plant for replacement parts is about £5,000 per annum not including the cost of manpower.

Brintons approached Sentridge for advice on converting the old DC motors to AC.

Phil Tomkinson, Sentridge’s Area Manager, explained “The DC to AC conversion is something we have done before and when Brintons suggested this as a solution to help increase capacity we immediately saw the potential.

Phil continued, “The biggest challenge we faced was the increase in the demand for power by bringing in the additional machines, with each motor rated at 75 kW, bringing the demand close to 1 MW.”

Initial thoughts were that the factory’s transformer capacity was not sufficient to handle the increased loading from the additional carding machines and spinning frames. This was because the DC solution gave poor factor of about 0.4, which meant heavy current usage. However the AC solution vastly improves the power factor, reducing current and subsequently active power.

Try before you buy

Sentridge operates a “try before you buy” scheme which runs real-time tests on-site, demonstrating the cost saving potential before any investment is made. Sentridge undertook analysis on the transformers, logging all loading and calculating various “what if…” scenarios over two weeks. The results confirmed that the 400 A busbars did not need to be upgraded, nor did the transformers have to be increased in capacity. In fact, Sentridge calculated a significant saving in current across the Canalis busbar system (see table below) thereby avoiding an increase in busbar copper and any change to the installed transformers, substation and switchgear.

Although energy saving was not the motivation for the conversion, Sentridge’s calculations showed that a saving could be achieved across all spinning frames of £40,000 per year. We supplied, installed and commissioned  12 off ABB 75kW drives with IE3 high energy efficient motors.

The trial was undertaken with an early generation ABB industrial drive and revealed 19 percent energy savings, equating to 0.5 MW per year. Since the trial, ABB has introduced a more efficient drive, the ACS880, that features 4th generation motor control platform, DTC, and the energy savings are even greater, totaling some 504,000 kWh saved. Together with the installation of IE3 ABB motors, return on investment was expected within three years but when the Government’s Enhanced Capital Allowance is factored in payback drops to 2.6 years.