Glossary

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Unit of electrical current.

Current which, in the absence of a fault, flows to earth or conducting elements via components that have been intentionally placed, resistances or capacitors.

A circuit load in which the voltages and currents are analysed at all points, using common mode input voltages (the input is defined by the generation of common mode voltages). The analysis comprises the evaluation of common impedences, and to calculate the common mode currents that result.
It is important to note that the common mode current, resulting from the analysis of the common mode when the reference point is the earth, is called residual differential current, especially when concerned with aspects of protection.

Part of the input voltages for which the amplitude and phase (or polarity) are equal, and where between each input terminal is a point of reference (this can be arbitrary, but generally is the earth or mass) (IEV 303).
Moyenne des phaseurs qui représente les tensions entre chaque conducteur et une référence arbitraire, généralement la terre ou la masse (VEI 161).

Fault location device

Digital Signal Processor : specialized processor used in signal processing especially adapted for digital control in UPS equipment. The DSP can process a high quantity of data in real time (20 million instructions per second). This technology provides users with exceptional performance features in terms of voltage precision, output (efficiency) and reliability

The voltage between two given conductors (IEV 161).

Mechanical device or association of devices intended to cause the opening of contacts when the differential residual current is reached, in specified conditions with a given value

A load is termed distorted when the current / voltage relation is not linear. For example: IT equipment using chopping power supply with a capacitive input filter. These loads generate harmonic current.

A function that provides energy savings. When in ECO-MODE, the load operates under normal conditions and is supplied by the emergency power supply. Should this source be compromised, the UPS automatically takes over to assure continuous power supply to the applications

Power electronics equipment

Electro-magnetic compatibility is the ability of a device to satisfactorily operate in its electro-magnetic environment without in turn producing intolerable electro-magnetic interference within this environment.

Electromagnetic field

Electrostatic discharge

The conducting mass of the earth, which is normally taken to be at zero potential (IEV 826-04-01).

A conducting part that can be incorporated in a particular conducting environment, such as concrete or coke in electrical contact with the earth , for example (IEV 195-02-01).

A fault current that flows to earth.

Formerly called "neutral load".

See "earth connection".

Part of the installation's earthing that is limited to the eathing electrodes and their interconncetions (IEV 604-04-07).
Earth (connection) (the term is best avoided in this sense) : all the conductors that are buried or placed on the ground to improve conductivity next to an aerial (IEV 712-04-57).

Final Draft International Standard.

Current in a given point of the circuit (or network) resulting in a fault in another point of the same circuit (IEV 603-02-25).

Earthing of a point in the material's electrical circuit (its neutral point, for example), necessary for the correct operation of the material and network (IEV 604-04-12).

(Gate turn off, thyristors)

A term used for the batteries (or battery pack) of certain UPS equipment. Allows the user or maintenance personnel to exchange the battery without shutting down the UPS

International Electronics Commission

International Electrotachnical Vocabulary. Listed in the IEC 60050-X series

Insulate Gate Bipolar Transistor : rapid changeover power transistors used in the converter bridges of UPS produced by SOCOMEC UPS that provide exceptional operating performance

Insulation monitoring device

This indicates the degrees of protection described in standard 60529 "degree of protection provided by enclosures (IP code)" against contact with live parts and against foreign bodies (the first figure and optional additonal letter) and against water penetration (second figure and optional second additional letter).

Internal point of coupling (in an industrial network)

In an IT arrangement all the active parts are either insulated from the earth or connected to the earth in a single point via an impedance, and with the electrical installation's masses connected to earth.

Often confused with the UPS, the inverter is in fact one of 3 main sub-assemblies of the UPS (with the rectifier and battery). The inverter transforms the dc voltage supplied by the rectifier or battery into perfectly stable ac voltage.

(In an instllation)
Current which, in the ansence of a fault, flows to earth or conducting elements (IEV 826-03-08).

Or "on active standby" or "off-line intelligent" technology.
Under normal operating conditions the load is supplied by the mains. The equipment corrects mains variations and controls the output voltage. Should mains outage occur, the load is transferred to the UPS and its battery back up until such a time as normal mains usage can be restored.

A load is termed linear when the consumed current has the same form as the supply voltage. For example: resistance.

Power supply channel designed to enable UPS section(s) to be isolated for safety reasons during maintenance operations and/or to ensure permanent load power supply. This channel can be supplied either by the principal power source or from an emergency source..

A conductive part of electrical equipment that can be touched and that is normally not live, but may become so in case of fault (IEV 826-03-02).
A conductive part of electrical equipment that can be touched directly, that is not normally live but may become so in case of fault (IEV 441-11-10).

Elements not forming part of the electrical equipment that are protected by equipotential coupling if simultaneously accessible

Current which, in the absence of a fault, flows to earth or conducting elements via insulating material.
This current excludes the parts due to the intentional use of components on measuring or filtering circuits.

or "stand-by" technology.
Under normal operating conditions the load is supplied directly from the mains. In cases of outage, voltage drop or jump, the load is transferred to the UPS and its battery back up. This technology is particularly suited to low power UPS systems.

or "in continuous operation" technology.
When "on line", the UPS is operating continually. Electrical energy is supplied by the UPS via its rectifier-charger function. This provides a perfect, high quality electrical signal. The UPS battery back up function only comes into operation if there is a mains outage or if the mains supply has wide variations in voltage or frequency. The ON-LINE function thus offers an autonomus electrical supply, with full voltage and frequency control.

Connection point (PCC or IPC).

Common connection point on public mains.

Protection Extra Low Voltage for circuits connected to earth.

Protection and Monitoring Device

Pulse width modulation

The ratio between the active power consumed by the application (in W) and the apparent power supplied in VA. For linear loads, the power factor is equal to the displacement factor or cos phi

This type of conductor is prescribed for certain protection measures against electrical shock and is intended to be connected to some of the following parts (IEV 826-04-05) :
• earth
• conductor elements
• main earthing terminal
• earth connection
• distributing point connected to earth or to artifical neutral point
• metallic elements of the construction that do not form part of the electrical material
• parts protected by equipotential coupling, if simultaneously accessible

Mechanical device or association of devices intended to cause the opening of contacts when the differential residual current is reached, in specified conditions with a given value.

Radiofrequency interference or radioelectric interference.

An RFI filter is a filter that limits radiofrequency interference emissions

Designates a converter whose function is to transform mains ac voltage into dc voltage.

Rectifier that maintains the battery fully charged.

Algebraic sum of instantaneous values of the currents flowing through all the active conductors of a circuit at a given point in the electrical installation (IEV 826-03-09).

Security Extra Low Volatge for circuits not connected to earth.

Simple Network Management Protocol : standard IT network protocol.

A correct shutdown of the IT system with prior saving of files.

Autonomously supplied network, not connected to a mesh network.

Alternative supply channel (normal or emergency) controlled by a static electronic changeover switch. This device enables supplied equipment to be automatically switched to an emergency channel.

Total Harmonic Distortion
THD (symbol) see IEV 551-20
The ratio of the r.m.s. value of the harmonic content to the r.m.s. value of the fundamental component, or the reference fundamental component of an alternating quanitity.

The TN earthing arrangement has a point of supply directly connected to earth, and with the elctrical installation's masses connected to this point via protective conductors.

The TNC earthing arrangement is a TN arrangement in which the neutral and protection functions are combined in one single conductor (PEN) in the entire installation.

The TNCS earthing arrangement is a TN arrangement in which the neutral and protection functions are combined in one single conductor (PEN) in part of the installation (upstream of the TNS).

The TNS earthing arrangement is a TN arrangement in which a protective conductor distinct from the neutral is used in the overall arrangement.

The TT earthing arrangement has a power supply point that is directly earthed, with the installation's masses connected to earth via connections that are distinct from the supply earth connection.

Uninterruptible Power Supply (commonly called an 'inverter'). Denotes a power supply system able to permanently ensure power supply to any installation during electrical network failure.

The derived SI unit of electric potential.

The derived SI unit the apparent power to be supplied to the load. Apparent power is the product of voltage RMS values and the current consumed by the supplied application. P(VA) = U(V) x I (A)

The derived SI unit of active power consumed by the load. Active power is the product of the apparent power and the power factor.

Alternating current

Direct-current

Voltage regulation over time (the term is generally reserved for rapid variations - in the order of 1000V/ms).

Electrical connection that brings masses and conducting elements to the same (or neighbouring) potential (IEV 826-04-09).

Abbreviation of Kilo Volt-Ampere. Cf VA

Functional reference : A measurement reference point of different potentials (voltage measurement, often in control circuits).