Power management

The basic objectives of a reactive power management system can be identified by the following for LT and HT distributions ... 

This product can be reduced by reducing X, using series capacitance with a reactance X, which will reduce to - Xq. This is where reactive control plays a major role. By meticulous reactive power manage-ment, the Ferranti effect can be controlled and the electrical line length increased to the desired level. It is a different matter that the electrieal length of the line cannot be raised infinitely, for reasons of stability, as discussed later. 

Power management capability has reached most office equipment, but on many devices the feature is not enabled or (for some PCs or monitors) is prevented from functioning. Equipment with functioning power management or that is turned off manually at night and on weekends use considerably less, and devices left fully on constantly use much more. 

Nordman, B. Piette, M. A. Kinney, K. and Webber, C. (1997). User Guide to Power Management for PCs and Monitors. Report No. LBNL-39466. Berkeley, CA Lawence Berkeley National Laboratoiy. 

Technologically it is important that smart battery packages, featuring power management by electronic devices within the battery package, are becoming a necessity due to the sensitive charging characteristics of Li and Ni-MeHy batteries, it should be noted that the same principles at a fraction of the cost have been successfully applied realized by simple reversal protection and overflow components by the low-cost RAM batteries. 

Power management may involve devices that regulate the on and off times of selected loads, such as fans, heaters, and motors. These devices reduce the electrical demand (kilowatts) and regulate energy consumption (kilowatt hours). In the past most of the energy savings has mainly been in heating. 

Linking power management systems to control systems allows the power information to flow from both systems. Load profiles can be developed to find any energy inefficiencies. Energy scheduling can be used to find the optimum energy schedule for new product lines or processes. 

Some power management devices are known as load shredders. They reduce the demand or average load in critical demand periods by interrupting the electrical service to motors, heaters, and other loads for short periods. Since the load which has been turned off would normally have been operating continuously, the overall effect is to reduce the average load or demand for that period of time. The instantaneous load when the load is operating remains the same. When the period involved... 

Appliance and equipment efficiency standards are having a notable impact on electricity demand in the United States. Standards have lowered national electricity use by 3%. A few energy efficiency measures, such as power-managed personal computers, have been widely adopted without financial incentives or much utility involvement. 

We come now to the third box in Figure 8.2, preparing yourself to use power. This refers to the mental and psychological preparation that you may need to make in order to exert your personal power. Management consultant and counsellor George W. Watts has described personal power as being a function of singleness of purpose and lack of impediments (1993 107). That succinct summary touches the essence. 

Ben 01] Benini, Luca, Giuliano Castelli, Alberto Macii, and Riccardo Scarsi, Battery-driven dynamic power management, IEEE Design Test of Computers, pp. 53-60, March-April 2001. 

Bro 03] Brock, Bishop and Karthick Rajamani, Dynamic power management for embedded systems, Proceedings of the IEEE International SOC Conference, pp. 416—419, September 2003. 

---