Case Study – Power quality investigation in a manufacturing company

Sector: Industrial Sector

Project: Power quality investigation in a manufacturing company



Most companies view energy as free issue within the production process. They also do not place large emphasis on the effective delivery of the energy to its point of use. This is driven by a number of reasons, one of which is a leaking electrical system which can only be visually identified if it creates a brown out or black out – in other words a shorting of the system. Manufacturers that are in older facilities are prone to having an amount of their energy return to their utility provider without them using it. This is caused by a number of technical reasons including incorrect wiring or phase imbalance. This energy usually flows back via the neutral cable.




A manufacturing company was concerned that its energy bills were rising at a faster pace than they expected. In order to find out where their energy was going, a mapping exercise was conducted.

A number of assets were found to be inefficient but a larger issue was also highlighted in the amount of energy being returned down the neutral. At 50 amps this represents approximately 12kW per hour or £10,500 per year if left untreated.




A detailed power quality investigation was undertaken to identify why an individual phase was running higher than the other two and why the 50 amps was detected in the neutral.

As the manufacturing operation has grown organically over the years, so new systems have been added to the electrical system without balancing them. This caused an imbalance to the phases and a part cause of the neutral outflow. On-going work to trace the rest of the neutral outflow is continuing.

Specialist power quality analysis equipment is expensive and not needed on a day to day basis. However, all manufacturers should be investing in periodic system health checks to ensure optimum running.

These should not be seen as a compliance test but rather an efficiency test, as the cost of not doing so can be high. In the above example the loss is equivalent to a months’ worth of energy.