Energy management and energy conservation start with the ability to monitor power and energy use.   For electrical systems, this involves measuring DC or AC power (Watts, VA, VAr) or energy (Wh, VAh, VArh).  In fixed installations, digital panel meters offer a range of display formats, capabilities & sizes. Single display power/energy meters start at $150.  Multiple display meters with user selectable parameters are available for $200-800, depending on configuration and capabilities. Bargraph power meters, which show a digital reading and analog level, start around $350.   Advanced parameters, including power factor, demand & harmonics, are standard on many models. Most meters also offer options for setpoint alarms & network communications.  Specialized meters are available for applications such as generator monitoring or load shedding.  See the more popular digital:       Power Meters       Energy Meters       Bargraph Meters  For older systems, we offer a selection of Analog Power Meters and panel adapters.       Applications that don't require a local readout can use a transducer system to monitor power and energy.  Data is collected through a network or computer interface.  Sub-metering can be implemented with either a panel meter or transducer system. Split core current sensors and potential transformers are often used to simplify installation of these products.   For portable or temporary use, test instruments such as power analyzers (or power quality monitors) are a convenient solution. These products connect to single phase or three phase systems. In addition to basic power and energy measurements, some units monitor inrush current, voltage dips/spikes and mains interruptions. Many models offer graphic displays and extensive waveform/data storage. Reference Information: Power Measurement application notes.  Current Transformer application notes. Power & Energy Monitoring presentation (pdf).