Glossary

Common terms, key industry/regulatory groups and general information about the precision time Industry. Click to expand for more information

BIPM - Bureau International des Poids et Mesures

Bureau International des Poids et Mesures (International Bureau of Weights and Measures) CCTF: Consultative Committee for Time and Frequency

Ensures world–wide uniformity of measurements and their traceability to the International System of Units (SI). The worldwide organization that coordinates standard frequencies and time signals. The BIPM maintains Coordinated Universal Time (UTC).

http://www.bipm.org/

FERC - Federal Energy Regulatory Commission

The Federal Energy Regulatory Commission, or FERC, is an independent agency that regulates the interstate transmission of electricity, natural gas, and oil. FERC also reviews proposals to build liquefied natural gas (LNG) terminals and interstate natural gas pipelines as well as licensing hydropower projects. The Energy Policy Act of 2005 gave FERC additional responsibilities as outlined in FERC's Top Priorities and updated Strategic Plan.

http://www.ferc.gov/default.asp

IEC - International Electromechanical Commission

The IEC is the world's leading organization that prepares and publishes International Standards for all electrical, electronic and related technologies — collectively known as "Electrotechnology". Wherever you find electricity and electronics, you find the IEC supporting safety and performance, the environment, electrical energy efficiency and renewable energies.The IEC also manages conformity assessment systems that certify that equipment, systems or components conform to its International Standards.

http://www.ntp.org/

IEC 61508 - Functional safety of electrical/electronic/programmable electronic safety-related systems

IEC 61508 is an international standard of rules applied in industry. It is titled "Functional safety of electrical/electronic/programmable electronic safety-related systems". IEC 61508 is intended to be a basic functional safety standard applicable to all kinds of industry. It defines functional safety as: “part of the overall safety relating to the EUC (Equipment Under Control) and the EUC control system which depends on the correct functioning of the E/E/PE safety-related systems, other technology safety-related systems and external risk reduction facilities.”

http://www.iec.ch/zone/fsafety/

IEC 61580 - International Standard for Power Substation Automation Systems

IEC 61850 Communication Networks and systems in Substations IEC 61850 is the international standard for substation automation systems. It defines the communication between devices in the substation and the related system requirements. It supports all substation automation functions and their engineering. Different from that of earlier standards, the technical approach makes IEC 61850 flexible and future-proof. The ideas behind IEC 61850 are also applicable in areas of automation such as control and monitoring of distributed generation. The use of IEC 61850 in areas of water and gas is being discussed.

www.iec.ch

IEEE - Institute of Electrical and Electronics Engineers

IEEE is the world’s largest professional association advancing innovation and technological excellence for the benefit of humanity. IEEE and its members inspire a global community to innovate for a better tomorrow through its highly cited publications, conferences, technology standards, and professional and educational activities. IEEE is the trusted “voice” for engineering, computing and technology information around the globe.

www.ieee.org

IEEE 1588 - Synchronization of clocks in measurement and control systems (See also PTP)

This standard defines a protocol enabling precise synchronization of clocks in measurement and control systems implemented with technologies such as network communication, local computing and distributed objects. The protocol will be applicable to systems communicating by local area networks supporting multicast messaging including but not limited to Ethernet. The protocol will enable heterogeneous systems that include clocks of various inherent precision, resolution and stability to synchronize. The protocol will support system-wide synchronization accuracy in the sub-microsecond range with minimal network and local clock computing resources. The default behavior of the protocol will allow simple systems to be installed and operated without requiring the administrative attention of users.

http://www.nist.gov/el/isd/ieee/ieee1588.cfm

IEEE/PES - IEEE/Power and Energy Society

The IEEE Power & Energy Society is a worldwide, non-profit association of more than 24,000 individuals engaged in the electric power energy industry. Our mission is to be the leading provider of scientific information on electric power and energy for the betterment of society and the preferred professional development source for our members. PES members are involved in the planning, research, development, construction, installation, and operation of equipment and systems for the safe, reliable, and economic generation, transmission, distribution, measurement, and control of electric energy.

http://www.ieee-pes.org/

iPC or IPC - Association Connecting Electronics Industries

Formerly the Institute for Interconnecting and Packaging Electronic Circuits, the IPC is dedicated to “furthering the competitive excellence and financial success of its members, who are participants in the electronics industry. In pursuit of these objectives, IPC will devote resources to management improvement and technology enhancement programs, the creation of relevant standards, protection of the environment, and pertinent government relations.” Arbiter is particularly interested in the work being done by the Lead Free Solder initiative under the IPC.

http://www.ipc.org/default.aspx
http://leadfree.ipc.org/

IRIG-B - Inter-Range Instrumentation Group time code

This standard defines the characteristics of six serial time codes presently used by the U.S. Government and private industry. Year information has been added to IRIG codes A, B, E, and G. Standardization of time codes is necessary to ensure system compatibility among the various ranges, ground tracking networks, spacecraft and missile projects, data reduction facilities, and international cooperative projects.

http://irigb.com/IRIGB_standard.html

ms - Millisecond

Millisecond = one thousandth of a second (1/1,000)

Noted as 'ms'

Example: 1 ms

NASPI - North American Synchrophasor Initiative

The mission of the North American SynchroPhasor Initiative is to improve power system reliability and visibility through wide area measurement and control. Synchrophasors are precise grid measurements now available from monitors called phasor measurement units (PMUs). PMU measurements are taken at high speed (typically 30 observations per second – compared to one every 4 seconds using conventional technology). Each measurement is time-stamped according to a common time reference. Time stamping allows synchrophasors from different utilities to be time-aligned (or “synchronized”) and combined together providing a precise and comprehensive view of the entire interconnection. Synchrophasors enable a better indication of grid stress, and can be used to trigger corrective actions to maintain reliability.

The NASPI community is working to advance the deployment and use of networked phasor measurement devices, phasor data-sharing, applications development and use, and research and analysis. Important applications today include wide-area monitoring, real-time operations, power system planning, and forensic analysis of grid disturbances. Phasor technology is expected to offer great benefit for integrating renewable and intermittent resources, automated controls for transmission and demand response, increasing transmission system throughput, and improving system modeling and planning.NASPI is a collaborative effort between the U.S. Department of Energy, the North American Electric Reliability Corporation, and North American electric utilities, vendors, consultants, federal and private researchers and academics. NASPI activities are funded by DOE and NERC, and by the voluntary efforts of many industry members and experts

http://www.naspi.org/

NERC - North American Electric Reliability Corporation

NERC ensures the reliability of the bulk power system in North America. To achieve that, NERC develops and enforces reliability standards; assesses reliability annually via 10-year and seasonal forecasts; monitors the bulk power system; and educates, trains, and certifies industry personnel. NERC is a self-regulatory organization, subject to oversight by the U.S. Federal Energy Regulatory Commission and governmental authorities in Canada.

http://www.nerc.com/

NIST - National Institue of Standards and Technology

Founded in 1901, NIST is a non-regulatory federal agency within the U.S. Department of Commerce. NIST's mission is to promote U.S. innovation and industrial competitiveness by advancing measurement science, standards, and technology in ways that enhance economic security and improve our quality of life. From automated teller machines and atomic clocks to mammograms and semiconductors, innumerable products and services rely in some way on technology, measurement, and standards provided by the National Institute of Standards and Technology.

http://www.nist.gov/index.html

ns - Nanosecond

Nanosecond = one billionth of a second (1/1,000,000,000)

Noted as 'ns'

Example: 40 ns

NTP - Network Time Protocol

NTP is a protocol designed to synchronize the clocks of computers over a network. NTP version 3 is an internet draft standard, formalized in RFC 1305. NTP version 4 is a significant revision of the NTP standard, and is the current development version, but has not been formalized in an RFC.

http://www.ntp.org/

PMU - Phasor Measurement Unit

See Synchrophasor

PSRC - Power System Relaying Committee

Assists the protective relaying industry by providing leadership in all items related to its scope. Leadership is provided through the development of technical documents. These may take the form of: Standards, Technical papers, reports, industry surveys, panels sessions and tutorials.

http://www.pes-psrc.org/

PTP - Precision Time Protocol

High precision time synchronization protocol for networked measurement and control systems. Accuracy in the sub-microsecond range may be achieved with low-cost implementations.[1] It is defined in the IEEE 1588-2002 and 1588-2008 standards, officially entitled "Standard for a Precision Clock Synchronization Protocol for Networked Measurement and Control Systems". "IEEE 1588 is designed to fill a niche not well served by either of the two dominant protocols, NTP and GPS. IEEE 1588 is designed for local systems requiring very high accuracies beyond those attainable using NTP. It is also designed for applications that cannot bear the cost of a GPS receiver at each node, or for which GPS signals are inaccessible."

http://en.wikipedia.org/wiki/Precision_Time_Protocol

PTTI - Precise Time and Time Interval

A department of Defense Military standard which details a mechanism and waveform for distributing highly accurate timing information.

http://www.pttimeeting.org/

SA - Selective Availability

GPS includes a feature (currently disabled as of May 1, 2000) called Selective Availability (SA) that adds intentional, time varying errors of up to 100 meters (328 ft) to the publicly available navigation signals. This was intended to deny an enemy the use of civilian GPS receivers for precision weapon guidance. SA errors are actually pseudorandom, generated by a cryptographic algorithm from a classified seed key available only to authorized users (the US military, its allies and a few other users, mostly government) with a special military GPS receiver. Mere possession of the receiver is insufficient; it still needs the tightly controlled daily key. Typical SA errors were 10 meters (32 ft) horizontally and 30 meters (98 ft) vertically. Since being turned off in 2000 the SA has been reinstated at least twice (Kuwait and Iraq wars). When reinstated GPS clocks which have been designed without provisions to correct for the added error range in their tuning algorithms typically fail until the SA is turned off again.

http://www.gps.gov/systems/gps/modernization/sa/

SNTP - Simple Network Time Protocol

A less complex form of NTP that does not require storing information about previous communications is known as the Simple Network Time Protocol or (SNTP). It is used in some embedded devices and in applications where high accuracy timing is not required.

Stratum Levels

Stratum levels define the distance from the main reference timing source and is defined by Network Time Protocol RFC 1305. The highest level is Stratum 0. Devices such as GPS, which get their time from a primary time source such as a national atomic clock ar often considered Stratum Level 0 devices. Stratum 1 servers source their time from a Stratum 0 device. Stratum 2 and beyond obtain their time from Stratum 1 servers. Therefore, the further away a network is from a primary source, the greater the chance of signal degradations due to variations in communications lines and other factors, hence lower stratum level ratings.

http://www.faqs.org/rfcs/rfc1305.html

Synchrophasor - Phasor Measurement Unit (PMU)

A Phasor measurement unit (PMU) measures the electrical waves on an electricity grid to determine the health of the system. In power engineering, these are also commonly referred to as synchrophasors and are considered one of the most important measuring devices in the future of power systems. A PMU can be a dedicated device, or the PMU function can be incorporated into a protective relay or other device.

http://www.naspi.org/

Time Measurement Units

Common symbols and meaning used in precise time measurement
ms – Millisecond = one thousandth of a second (1/1,000)
µs – Microsecond = one millionth of a second (1/1,000,000)
ns – Nanosecond = one billionth of a second (1/1,000,000,000)

µs – Microsecond

Microsecond = one millionth of a second (1/1,000,000)

Noted as 'µs'

Example 1 µs

UTC - Coordinated Universal Time

The international time standard is called Coordinated Universal Time or, more commonly, UTC, for "Universal Time, Coordinated". This standard has been in effect since being decided on in 1972 by worldwide representatives within the International Telecommunication Union. UTC is maintained by the Bureau International de l'Heure (BIPM) which forms the basis of a coordinated dissemination of standard frequencies and time signals. The acronyms UTC and BIPM are each a compromise among all the participating nations.

http://en.wikipedia.org/wiki/Coordinated_Universal_Time

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