Implementing power quality solutions: Success Stories

The local electrical utility worked with the company, installed metering and determined that most of the events were due to voltage sags. The plant is supplied at 26kV via an overhead line ; there is a dedicated 2500kVA transformer on site to provide the 480V operating voltage for the plant. The utility was unable to prevent sags many of which occurred during thunderstorms.

The plant is supplied via the local electrical utility at medium voltage 20kV and there are several transformers on site to provide the operating voltage of 480V. The company and the utility installed power quality monitors. The data produced showed almost all events were due to voltage sags which occur mainly during storms and bad weather. Omniverter was given data from the site and company management decided that they wished to apply any solution to one critical line which produces several million cookies per week

The company requested help from their electrical utility which installed power quality meters at the site. The utility determined that the site was experiencing multiple voltage sags, especially in stormy weather and that while some of these sags originated from local conditions such as tree branches contacting power lines the plant was also seeing the effect of voltage sags created on the high voltage transmission lines. The utility concluded that in some months there were over 20 voltage sags below 90% of nominal voltage and some of these were very deep.

The Dairy management believed that the problems were due to poor electrical power quality. They approached their electrical utility which installed power quality analyzers. They concluded that the Dairy was suffering not only from voltage sags but also from occasional complete loss of power for short periods. The dairy is fed at 480V but is located downstream from a utility 12.5kV medium voltage recloser so, whenever the recloser operated, the dairy experienced loss of power. Omniverter was invited to offer a solution. After analysis of the data and discussions with the utility it was found that any movement of the medium voltage recloser to a position downstream of the Dairy to reduce power loss was not economically feasible. The solution would need to correct both voltage sags and short term loss of power in an industrial environment with no clean room space available for a conventional UPS system. In most cases the loss of power lasted for only a few seconds

The Company installed power quality analyzers and worked with their local electrical utility to acquire data. They determined that almost all of the events were due to voltage sags and there was very little actual loss of power. Omniverter analyzed the data and learned from the customer that a solution should provide continuous voltage correction and voltage phase balance to keep the voltage in as tight a tolerance as possible to optimize their production runs.

The utility installed power quality monitoring equipment and determined that there were neighborhood power fluctuations and electrical flicker which they traced back to the quarry. When starting the rock crushers at the start of a work shift there would be a requirement for reactive power (kVAR) input that exceeded the capacity of the utility supply, resulting in a voltage sag on the network. This could also happen occasionally during the day if large rocks were being crushed or if both rock crushers came under peak load simultaneously. Wide variations in load resulted in the creation of electrical flicker

The data was shared with Omniverter and it was clear that almost all events recorded were due to voltage sags which occur most frequently during stormy weather. The hospital had started building a new dedicated cancer treatment center on a separate site and required protection against voltage sags for their new suite which included several LINAC’s.

The company had installed several power quality monitors throughout its facility, so it had several years of data on the electrical supply power quality. The plant is supplied at medium voltage 27.6kV to a transformer located inside the building which supplies an operational voltage of 600V to production areas. Omniverter was invited to help the company find a suitable solution to correct the voltage sags and improve production. Analysis of the data showed that over a 5 year period there had been only one power outage but many voltage sags. Omniverter was able to calculate the depth of voltage sags that cause a production stoppage.

The company was supplied by their electrical utility via an underground cable at 35kV which was transformed down to 480V for the production processes. They had installed power quality meters and working with their utility concluded that nearly all of the problems were caused by voltage sags. Omniverter was provided with data which showed that if a voltage sag between 50% and 90% of nominal voltage occurred then either damage to the cut or due to smearing or breakage of wire could occur. Most of the voltage sags were single phase events consistent with lighting strikes on high voltage transmission lines.