What is Power Trend Management?

Power trend management has very little to do with energy conservation, except that both practises are aimed at getting more productivity out of the existing facility without having to upgrade any electrical panels and wiring. Facility managers and operations managers are well aware of the benefits of seeking out more efficient ways to run their operations. Selecting more efficient plant equipment and applying the equipment more efficiently does greatly increase the benefits of power trend management.

High power peaks cost some users money every month because the utility charges a "demand" rate, or wire demand surcharge on top of the metered energy usage. The tuned PTM reduces this cost significantly. Power trend management is the practice of controlling the switching on and off of major plant loads for the purpose of reducing the amplitude of the power peaks set within the plant. Over time, this practice can be fine-tuned to the extent that the hourly, daily, and weekly, load curve at their meters is relatively flat. The art of power trend management is significantly different from load shedding. Although the Olson Power Trend Management (PTM) system is quite capable of doing load shedding, our perspective is that load shedding is a relatively brutal practice and quite contrary to plant operations needs and goals.

A fine-tuned PTM system applies slight delays to the start-up of loads that are under the control of some sort of automated device. These delays are, in some cases, slightly noticable. In most cases they are not. For example, consider a heating system that controls blower motors. The HVAC controller does not care if the blowers are started immediately or five seconds later. Certainly no one inside the plant will notice the difference. However, the electrical billing meters located at the main power panel do care, and very much so.

With a PTM system applied, individual loads are no longer started and stopped in ignorance of the resulting cumulative effect. A precise delay is automatically calculated and applied when needed, taking into account the entire load picture of a plant. Loads are statistically monitored and controlled so that they are not turned off and on in rapid succession. This intervention smooths the power demand by reducing peaks and raising the valleys. Wear on the plant equipment due to excessive start-ups is also reduced. In special cases, loads can be kept running as opposed to stopping and starting.This intervention by the PTM system results in reductions in demand and energy costs.

The PTM system monitors individual load characteristics. Changes in start-up time, start-up current, and normal current for each load are watched over time. This reveals trends toward unscheduled shutdowns. Simple load protection is provided as well. For example, a motor under PTM control will not be allowed to start if the AC power is not within tolerances, or if a load fault is detected. Whenever a monitoring function senses an abnormal line or load condition it generates important alarms that can be picked up by users in a variety of ways: pager, e-mail, or workstation alarms. This provides the means by which plant managers can prevent a day from starting with an air conditioning or heating system outage, or other impediments to revenue generation.

In summary, a tuned PTM system provides facility and operations managers with a more constant electrical load curve. The area under the curve represents the plant's energy usage. It is roughly equal to or less than the time before the PTM. More electrical energy is now available for expanding operations because the main breaker is no longer at risk of tripping during peak periods.

The PTM provides an ad hoc metering function. When the utility bill comes the plant manager can reconcile the metered power demand and energy with the accumulators in the PTM system. Small differences in these amounts are expected. Large differences in favor of the utility may be of interest to government auditors.