Sinergy was called in to survey the sites’ electrical demand/usage over a four week period when the facilities were operating at near maximum capacity.
The business mantra ‘to measure is to manage’ proved just the case for a well-known multi-site leisure facility provider wanting to identify ways of reducing power bills across its operations.
The business, which runs a number of leisure sites around the UK providing family fun pools, restaurants and accommodation, was particularly interested in identifying savings from peak lopping and overnight wastage elimination.
Sinergy was selected for a number of reasons, one of the most important being that it could install enough portable energy loggers to complete a parallel monitoring exercise on the 40-plus distribution transformers. It was also imperative that sub-metering could take place without turning off the power supply to any facilities.
Parallel Feeder Cables
The easiest way to measure load current on the distribution transformers was on outgoing cables where safe access was available. It is common for these phase cables to be run in parallel pairs or sets of three or four. However the span of the cables did not cause installation problems – Sinergy e-Tracker’s flexible CT’s were long enough to span the parallel conductors. The e-Trackers were magnetically clamped to the transformer casings.
A 3 phase voltage measurement reference was accurately derived via Sinergy’s EV-TRAC synthesizer. The EV-TRAC plugs into a single phase socket and has an electrostatic phase identity feature essential in this style of measurement. Some manufacturers rely on their instruments’ software to automatically sort out the phase identity and rotation. This can be unreliable and lead to measurement inaccuracies. For example, if the power factor of one phase falls below about 0.7, then to some existing software algorithm, this phase appears more like the adjacent phase.
The peak demand of 500kW at 10.30pm on the 15th had a significant effect on the site’s monthly Maximum Demand charge and annual Capacity Charge. These two elements can represent up to 25% of an electricity bill. The question was whether peak demands at other distribution transformers coincided to push the 500kW level two or three times higher. The Excel uplink within e-Tracker’s Deltrax software package enables cumulative additions and comparisons with other sites to be made. However the solutions to seemingly complex questions are often easy – disable some equipment for the night and use e-Tracker to determine what effect it has on the profile and most importantly. Deltrax should display an improvement and its tariff section will work out the appropriate cost saving.
Peaks and troughs
Deltrax software was used to produce demand profile graphs for the survey report, with daily and weekly graphs of multi and single parameter graphics. A kW demand profile of a swimming arena is shown. The survey results were dramatic, with a peak demand of more than 500kW (level A) and heavy daytime consumption (level B). Questions were raised over why the midnight to 8am usage did not fall to say 15-20% (level C) as may have been expected. More puzzling were the frequent short dips from level C to level D. What was turned off to cause them and could it be extended for the whole night period? We estimated that if overnight demand fell for eight hours to the 120kW level of these short lived dips, there would be a saving in consumption of some 7,000 kWh per week. Tight demand control of this nature overnight for just the summer season would lead to savings of some £3,000-£4,000 in KWH unit charges in this swimming pool area alone.