The metering industry has no shortage of technical terminology and keeping it all straight is a challenge. In addition, there is terminology you might encounter on the ESIS website that could use a simple definition as well, which is why ESIS presents this a glossary of common electrical & power metering terminology.
Short for Alternating Current, it’s an electric current commonly used in mains power, that periodically reverses direction 50 or 60 times a second (50Hz or 60Hz), whereas direct current only flows one direction. DENT power data loggers are designed to measure alternating current using current transformers.
An amp-hour (Ah) is a unit of electric charge (or energy), having dimensions of electric current times time, equal to the charge transferred by a steady current of one amp flowing for one hour.
An ampere is a unit of measure for an electrical current; the amount of current that flows in a circuit at an electromotive force of one Volt and at a resistance of one Ohm. Abbreviated as amp. DENT power meters are designed to measure many parameters, including amps.
Amplifier/Integrator circuitry is built into several DENT products, including the RōCoil mV CTs (discontinued), PowerScout Series, and ELITEpro XC meter. This circuitry, which is connected to the output of a Rogowski coil, provides an output signal that is proportional to the current. In the case of the RōCoil mV, this circuitry must be externally powered using a wall transformer.
Analog Input Channels
Analog input channels are helpful when used in conjunction with power measurements to correlate the consumption of electricity with environmental, HVAC plant performance, or other process conditions. Typical uses might include logging ambient temperature, building temperatures, solar insolation, tank pressures, duct flows, etc. For example, the ELITEpro XC accepts 0/4-20mA externally powered current loop or 0-30VDC single-ended sensors on the analog input channels.
Acronym for American National Standards Institute, which is a private, non-profit organization that oversees the development of voluntary consensus standards for products, services, processes, and systems in the United States. Several DENT products meet ANSI requirements for accuracy (i.e., the PowerScout 3037 meets the ANSI C12.20-2010 accuracy standard for revenue grade Class 0.2 performance).
Apparent Power (kVA)
The product of a circuit’s voltage and current, without reference to phase angle. DENT power meters are designed to measure many parameters, including apparent power.
Abbreviation for the American Society of Heating, Refrigeration, and Air-Conditioning Engineers. ASHRAE performs research, writes standards, and holds conferences for continuing education. DENT participates in one ASHRAE event, the AHR Expo, held in January or February each year.
AWG is the abbreviation for American Wire Gauge; the standard for gauging the size of wires (electrical conductors). The cross-sectional area of each gauge is an important factor for determining its current-carrying capacity.
BACnet is a communications protocol for Building Automation and Control (BAC) Network that leverages the ASHRAE, ANSI, and ISO 16484-5 standard. BACnet was designed to allow communication of building automation and control systems for applications such as heating, ventilation, and air conditioning (HVAC) systems and their associated equipment. The DENT PowerScout Series instruments are capable of BACnet communication. See the BACnet website for more information.
A meter that is capable of measuring both delivered/imported (+kW) power and received/exported (-kW) power. The term “bi-directional metering” is common in renewable applications.
A CE Mark is mandatory for certain products sold within the European Economic Area. It is similar to the FCC Declaration of Conformity used on certain electronic devices sold within the United States. A CE Mark signifies that a product meets high safety, health, and environmental protection requirements.
Clamp-On Current Transformer
Clamp-on current transformers are intended for one-handed operation during temporary energy audits. They are designed for broad utility in a compact shape. Clamp-On CTs are most often sold with ELITEpro XC instruments as their easy-to-use design makes them ideal for temporary measurement projects.
The material through which electricity is transmitted, such as an electrical wire, transmission line, or bus bar. Current transformers are placed around a conductor to measure the flow of electricity.
A tubular material used to encase and protect one or more electrical conductors. Conduit is most often used in permanent installations with PowerScout meters.
An electricity consuming apparatus connected to a generating system. Example: an electric motor.
The CONTACTlogger, one model in the DENT SMARTlogger Series (discontinued in 2019), is designed for monitoring relay closures, switches, and digital on/off signals. It comes with a 3-foot pair of wires that are connected to the switch or relay. The CONTACTlogger can be only be used on un-energized, “dry contact” devices.
Also called “alligator clips.” Croc clips are connected to the end of the voltage leads on ELITEpro XC instruments. They are used to connect the meter to voltage inside the electrical panel. Five colours are available: blue, black, red, white, and yellow (typically only used in installations outside the US).
Also called “Current Transformer” or “Current Sensor.” CTs are a type of transformer that is used to measure AC current. They produce an alternating current in its secondary which is proportional to the AC current in its primary. DENT CTs are connected directly to ELITEpro XC or PowerScout power meters and are available in a variety of current ranges and styles. They are selected depending on how many amps need to be measured and physical size constraints.
The CTlogger, one model in the DENT SMARTlogger Series (discontinued in 2019), is designed to monitor electric load status using a clamp-on current transformer. The CT is clipped over any conductor carrying 0.25 amps AC or more. The logger is activated when there are more than 0.25 amps of current flowing through the wire to the device being monitored.
Also called “Current Transformer” or “CT.” Current Sensors are a type of transformer that is used to measure AC current. They produce an alternating voltage which is proportional to the AC current in its primary. DENT CTs are connected directly to ELITEpro XC or PowerScout power meters and are available in a variety of current ranges and styles, including split-core, clamp-on, solid core (donut or toroid), or Rogowski coil. They are selected depending on how many amps need to be measured and physical size constraints.
Also called “Current Sensor” or “CT.” Current Transformers are a type of transformer that is used to measure AC current. They produce an alternating current in its secondary which is proportional to the AC current in its primary. DENT CTs have a built-in burden resistor to convert the current output of the transformer to a 333mV output and are connected directly to ELITEpro XC or PowerScout power meters and are available in a variety of current ranges and styles. They are selected depending on how many amps need to be measured and physical size constraints.
Current Transformer Window
A current transformer window is sometimes called its “opening.” The conductor you wish to measure is placed inside the window of the CT. You must ensure that the window of the CT is big enough to accommodate your conductor. Conductors can range in size from a small wire to a large busbar.
Discontinued in 2011, the DATApro was designed to measure, store, and analyze up to 100,000 records of data from all types of sensors such as gas, water, electric, steam, HVAC, compressed air, solid or liquid waste, security, weather, or manufacturing process lines. The ELITEpro XC, with four analog input channels, is the replacement product.
DC, or Direct Current, is the unidirectional flow of electric card. Direct current is produced by sources such as batteries, power supplies, thermocouples, solar cells, or dynamos. The electric current flows in a constant direction, distinguishing it from alternating current (AC). “Hall Effect sensors” are sensors that can measure DC current. DENT does not carry this type of sensor.
A delta circuit is a three-phase electrical configuration where three wires are required for transmission. Delta systems are commonly used for any large motors or heaters that don’t need a neutral. Delta is also used in power transmission because it’s expensive to run a fourth neutral wire for long distances.
A charge for the maximum rate at which electrical energy is used during peak hours of a billing period. Demand charges are imposed on the basis of the possible energy demand, instead of to the energy actually consumed.
Discontinued in 2011, the ELITEpro Recording Poly Phase Power Meter was designed to pinpoint electric usage and quantify consumption by measuring, storing, and analyzing volts, amps, watts, volt-amps (VA), volt-amps reactive (VAR), Kilowatts (kW), kilowatt-hours (kWh), kVAh, kVARh, and Power Factor. It was discontinued with the release of the ELITEpro SP power meter.
Discontinued in 2013, the ELITEpro SP Power Meter was designed to replace the ELITEpro Recording Poly Phase Power Meter. As a direct replacement, it offered many of the same measurement capabilities, but with increased storage. In addition, the ELITEpro SP had line-power, 8MB memory, and a USB port standard. Like the ELITEpro before it, this meter was designed to pinpoint electric usage and quantify consumption by measuring, storing, and analyzing volts, amps, watts, volt-amps (VA), volt-amps reactive (VAR), Kilowatts (kW), kilowatt-hours (kWh), kVAh, kVARh, and Power Factor. This model was also the first ELITEpro to allow the use of RōCoil (Rogowski) current transformers without an external amplifier/integrator. The ELITEpro SP was subsequently replaced by the ELITEpro XC.
Introduced in 2013, the ELITEpro XC is the current-generation of ELITEpro Series meter in the marketplace. It was designed to replace the ELITEpro SP. Like the ELITEpro SP, it is designed to pinpoint electric usage and quantify consumption by measuring, storing, and analyzing volts, amps, watts, volt-amps (VA), volt-amps reactive (VAR), Kilowatts (kW), kilowatt-hours (kWh), kVAh, kVARh, and Power Factor. It features 16MB memory, standard Ethernet, standard USB, and a range of communication options including Wi-Fi and Bluetooth.
ELOG Software is a Windows-based program designed to set up the ELITEpro Series meters, display metered values, and retrieve and analyze the collected data. ELOG graphically displays recorded data, performs analysis, and facilitates automatic remote data collection. ELOG is provided at no additional charge with the purchase of an ELITEpro XC and is also available as a free download on the DENT website.
The process of determining energy consumption, by various techniques, of a building or facility. The goal of the audit is to identify opportunities to reduce energy consumption with the goal of saving money over time. The ELITEpro XC is commonly used to perform energy audits in commercial and industrial applications.
ETL is recognized as an NRTL in the United States and, in a similar capacity, as a Testing Organization and Certifying Body in Canada by the Standards Council of Canada. A product bearing the ETL Listed Mark is determined to have met the minimum requirements of prescribed safety standards and is generally considered equivalent to a UL Listed Mark. DENT split-core current transformers are ETL Listed (cETLus).
The number of cycles through which an alternating current passes per second; in the U.S. the standard for electricity generation is 60 cycles per second (60 Hertz). DENT ELITEpro XC and PowerScout Series meters can measure at either 60Hz or 50Hz (as configured in the software).
Fused Croc Clips
Sometimes referred to as “Fused Alligator Clips.” Much like the standard croc clips, fused croc clips are connected to the end of the voltage leads on ELITEpro XC instruments. They are distinguished from the regular croc clips because they include a 500mA fuse. They are used to connect the meter to voltage inside the electrical panel. Five colours are available: blue, black, red, white, and yellow (typically only used in installations outside the US). The fuses protect the circuits being measured from accidents such as closing a cabinet door over the wires which could cause the wires to short to ground.
Ground is a safety conductor with a low impedance path to earth. It is often called the “ground wire” or “safety ground.” It is either bare or has green insulation.
A Hot is any conductor (wire or otherwise) connected with an electrical system that has electric potential relative to electrical ground or neutral.
A device that converts direct current electricity (from for example a solar photovoltaic module or array) to alternating current for use directly to operate appliances or to supply power to an electricity grid.
A standard unit of electrical power equal to one thousand watts, or to the energy consumption at a rate of 1000 Joules per second.
Kilowatt Hour (kWh)
A unit or measure of electrical energy or consumption of 1,000 Watts over the period of one hour; equivalent to 3,412 Btu.
Leg typically refers to “hot leg” and is one of the multiple hot conductors in an electrical system. The most common single split-phase, 240V, systems feature a neutral and two hot legs. The most common three-phase systems will have three hot legs, 208V to each other, and 120V each to the neutral.
The LIGHTINGlogger, one model in the DENT SMARTlogger Series (discontinued in 2019)is designed to monitor the on/off status of lights. An internal photosensor detects a nearby light source and records its status with a time and date stamp.
Line Power is a standard feature on ELITEpro XC and PowerScout Series instruments. It allows the meter to be powered by the voltage service under measurement. Line powered instruments do not need to be connected to wall power or use a battery to operate.
A load is an electricity-consuming apparatus, circuit, or system (such as a refrigerator or building), connected to a generating system.
The MAGlogger, one model in the DENT SMARTlogger Series (discontinued in 2019), is designed to attach to a motor housing. It contains a magnetic field sensor that can detect whether the motor is operating. It records its operating schedule with a time and date stamp.
Measurement & Verification
Also called “M&V.” This is a term given to a process for quantifying savings delivered by an energy conservation measure, as well as the subsector of the energy industry involved in this practice. The ELITEpro XC is commonly used for M&V projects.
Modbus is a serial communications protocol originally published by Modicon (now Schneider Electric) in 1979 for use with its programmable logic controllers (PLCs). Simple and robust, it has since become the de facto standard communication protocol and is now a commonly available means of connecting industrial electronic devices. DENT PowerScout Series instruments can communicate via Modbus protocol.
The PowerScout HD Series meters are multi-circuit or multi-channel meters, meaning they are capable of monitoring a combination of 3-phase and/or 1-phase circuits at the same time. For example, they may be used to monitor the mains and several lighting circuits in a single electrical panel.
The National Electric Code, or NEC, is a set of regulations that have contributed to making the electrical systems in the United States one of the safest in the world. The intent of the NEC is to ensure safe electrical systems are designed and installed. The National Fire Protection Association (NFPA) has sponsored the NEC since 1911. The NEC changes as technology evolves and component sophistication increases. The NEC is updated every three years. Following the NEC is required in most locations.
The National Electrical Manufacturers Association, or NEMA, is the largest trade association of electrical equipment manufacturers in the United States. In addition to lobbying activities, NEMA publishes more than 600 standards, application guides, white papers, and technical papers. Customers often inquire about enclosures with specific “NEMA ratings,” such as 4X. Definitions of NEMA Enclosure Types can be found here. DENT Instruments is a member of NEMA.
Net Energy = consumed energy – produced energy. Net Metering is the practice of using a single meter to measure the consumption and generation of electricity by a small generation facility (such as a house with a wind or solar photovoltaic system). The net energy produced or consumed is sold to or purchased from the power provider, respectively. Multi-circuit PowerScout meters are typically used in Net Metering applications.
A Neutral wire is the return conductor of a circuit. United States electrical codes require that the neutral is neither switched nor fused and that it be connected to earth at the service panel only and at no other point in the building wiring system.
PhaseChek™ is a patented technology (Patent No. 7,612,552) which allows a user to see when the current sensors on the meter have been improperly wired or connected. This greatly reduces set-up time and helps to eliminate installation errors. PhaseChek is available on ELITEpro XC and PowerScout Series instruments.
Port forwarding allows remote computers (for example, computers on the Internet) to connect to a specific computer or service within a private local area network (LAN). In the case of the ELITEpro XC with Ethernet, port forwarding allows remote connection between the ELITEpro XC and a computer on another network through the firewall via ELOG software.
In electrical engineering, the power factor of an AC electrical power system is defined as the ratio of the real power flowing to the load to the apparent power in the circuit and is a dimensionless number in the closed interval of -1 to 1. A power factor of less than one means that the voltage and current waveforms are not in phase, reducing the wattage of the load. Power factor (aPF and dPF) is captured by the ELITEpro XC and PowerScout Series instruments.
PowerScout is the trade name given to the DENT Instruments line of submetering instruments. PowerScouts are typically installed permanently in electrical panels to give ongoing information about energy consumption. They are available in single-circuit (PowerScout 3037) and multi-circuit (PowerScout HD Series) versions.
Pulse inputs are available on the PowerScout 24 and are used to count, accumulate, and scale pulses received from non-DENT external pulse initiating meters such as gas, water, or other electrical meters.
Pulse outputs are available on PowerScout Series meters and are used to send kWh or other pulses to a pulse counting device, such as a data logger.
Revenue grade meters and current transformers meet rigorous testing and accuracy requirements. Typically, they meet ANSI C12.20-2010 Class requirements of better than 1% accuracy (see PowerScout Series). The term “revenue grade” in general use can mean different things to different organizations. It’s possible to have a meter meet the Class 0.2 accuracy requirements, but unless it’s paired with an equally accurate or better CT, the end result may or may not be considered “revenue grade.”
RMS (Root Mean Square)
For a cyclically alternating electric current, RMS is equal to the value of the direct current that would produce the same average power dissipation in a resistive load. DENT ELITEpro XC and PowerScout meters offer true RMS measurements using high-speed digital signal processing (DSP).
RōCoil is the DENT trade name for our line of Rogowski Coil current sensors. RōCoils are known for their installer-friendly features such as large window size, lightweight, wide current range, and mechanical flexibility for mounting in tight quarters. RōCoils can be used with both ELITEpro XC and PowerScout instruments.
RōCoil mV, discontinued in 2019, is the DENT trade name for our line of Rogowski Coil current sensors that include amplifier/integrator circuitry on the lead wire. This circuitry allows these CTs to be used on meters that do not have amplifier/integrator circuitry build in (such as the legacy ELITEpro meter). This circuitry means that the RōCoil mV requires external power, usually provided by a wall adapter (PX-XFMR).
Discontinued in 2019, the RōCoil TCA-5 is a three-channel integrating transconductance amplifier (TCA) that converts the 131mV/1000A electrical output signal from the RōCoil sensor to a 5 amp AC current, emulating a traditional current sensing transformer. The RōCoil TCA-5 is designed to make RōCoil CTs compatible with 5 amp current input power meters.
Rogowski Coil Current Sensor
A Rogowski coil, named after Walter Rogowski, is an electrical device for measuring alternating current (AC) or high-speed current pulses. It consists of a helical coil of wire with the lead from one end returning through the centre of the coil to the other end so that both terminals are at the same end of the coil. The coil is then wrapped around the conductor whose current is to be measured. RōCoil is the trade name given to the DENT line of Rogowski coil CTs.
RS-485 is a standard defining the electrical characteristics of drivers and receivers for use in serial communications systems. PowerScout instruments are capable of communicating via Modbus or BACnet over RS-485 networks.
ELITEpro Series instruments require that they be configured for use by first creating a Setup Table file in ELOG software and then loading the file into the meter. The Setup Table file will tell the meter what current sensors, recording interval, and service type it will be monitoring.
Shark clips for the ELITEpro Series can be used in place of the standard Croc Clips in applications where Croc Clips may not physically fit. They are designed for narrow installations and are rated for 600V.
Single phase power is the distribution of alternating current (AC) electric power using a system in which all the voltages of the supply are either in phase or out of phase by one half a cycle (180˚). Single-phase distribution is used when loads are mostly lighting and heating, and electric motors are small (5HP and under) (such as found in most US residential homes). DENT ELITEpro Series and PowerScout Series are designed to measure on single phase as well as three-phase systems.
The SMARTlogger Time-of-Use data loggers are designed to monitor the on/off status and total time-of-use data of power-consuming devices such as lights, motors, switches, or other electric loads generating at least 0.25 amps. There are four models of SMARTloggers available: LIGHTINGlogger, MAGlogger, CTlogger, and CONTACTlogger. SMARTloggers are battery-powered and record up to 32,000 records (on/off transitions) in internal memory. SMARTware software is used to configure the logger and download and analyze the data.
SMARTware is an easy-to-use Windows-based software application for use with DENT SMARTlogger Time-of-Use loggers. It can be used to download and analyze data from SMARTlogger instruments, configure the logger clock, and export recorded data as a CSV file to Excel.
Split Core Current Transformer
Split Core current transformers are an economical CT choice. Like other CTs, they provide a linear output voltage that is directly proportional to the input current. They are safely and easily installed over existing electrical power lines without disconnecting lines. They produce 333mV at full scale and are available for loads up to 1200A. They are compatible with ELITEpro Series and PowerScout Series instruments.
Submetering refers to the monitoring of the electrical consumption of individual equipment within a building, such as HVAC, lighting, refrigeration, kitchen equipment, etc. In addition to the “main load” meter used by utilities to determine overall building consumption, submetering utilizes individual “submeters” that allow building and facility managers to have visibility into the energy use and performance of their equipment, creating opportunities for energy and capital expenditure savings. PowerScout Series instruments are typically used for building submetering projects.
Test & Measurement
At DENT, Test & Measurement refers to a category of products designed for Measurement & Verification (M&V) studies, electrical load profiling, energy audits, and new technology assessment. DENT Test & Measurement products include the ELITEpro Series meters and SMARTlogger instruments.
Three-phase electrical power systems have at least three conductors carrying alternating current voltages that are offset in time by one-third of the period (120˚). A three-phase system may be arranged in a delta (Δ) or wye. DENT ELITEpro Series and PowerScout Series instruments are designed to monitor both single and three-phase power systems.
Time of Use (TOU)
Time-of-Use is the time a particular load is turned on. For example, how long, and at what time the lights have been on in a particular room. Time-of-Use data can be collected using the DENT SMARTloggers (sometimes called DENT TOU loggers).
Toroidal Solid Core CTs
Toroidal Solid Core CTs are transformers which use magnetic cores with a toroidal (ring or donut) shape. They consist of a circular ring or doughnut-shaped magnetic core of ferromagnetic material, such as a laminated iron or ferrite, around which wire is wound. Because the core is solid (as opposed to a Split Core), they require the existing electrical power lines to be removed for installation. Therefore, they are generally used in new building installations to minimize disruptions. The DENT RGT Series are toroidal current transformers which are designed for Revenue Grade IEEE Class metering applications. They are compatible with both ELITEpro Series and PowerScout Series meters.
Twisted pair is a type of wiring in which two conductors of a single circuit are twisted together for the purposes of cancelling out electromagnetic interference (EMI) from external sources. This type of wiring is used on several DENT current transformers, including split-core CTs.
UL (Underwriters Laboratory) is an American safety consulting and certification company. They provide safety-related certification, validation, testing, inspection, auditing, advising, and training services to a wide range of clients, including manufacturers. UL is a Nationally Recognized Testing Laboratory (NRTL). Several DENT instruments and CTs are UL Listed (cULus), including the ELITEpro XC, and PowerScout 3037, or Recognized (cRUus), including the board-only versions of the PowerScout HD meters.
Acronym for Variable Frequency Drive. A VFD is a type of adjustable-speed drive used in electro-mechanical drive systems to control AC motor speed and torque by varying motor input frequency and voltage. DENT power meters are capable of measuring the input side of the VFD, but not the output side, as the frequency is not set at either 60 or 50 Hz and the voltage may not be a sinusoidal waveform.
ViewPoint is a software utility that allows for easy configuration of the PowerScout meter. It allows a user to switch between communications protocols (Modbus or BACnet), check real-time metered values, read & write registers, update the scalar values, and select current transformers. It is provided at no additional charge with the purchase of a PowerScout meter and is also available on the DENT website as a free download.
A Wye is a three-phase voltage system with the three phases connected to a single neutral point (star). This allows the use of two different voltages from all three phases, such as a 277/480V system, which provides 277V between the neutral and any one of the phases and 480V across any two phases.
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Article Courtesy of DENT.