The dictionary for communication between SCADA systems, controllers, other electrical devices and people. All entries from A to Z.

Dic­tio­nary and Ency­clo­pe­dia in one: click on the expla­na­tion to open the entire entry in a new tab. The dark­er tech­nolo­gies have longer entries, while basic expla­na­tions hide behind the lighter summaries.




ARP — Address Resolution Protocol

The Address Res­o­lu­tion Pro­to­col (ARP) is a com­mu­ni­ca­tion pro­to­col used for dis­cov­er­ing the link lay­er address (e.g. MAC address) that is asso­ci­at­ed with a giv­en inter­net lay­er address, com­mon­ly IPv4.

The map­ping func­tion pro­vid­ed by ARP is crit­i­cal to the Inter­net pro­to­col suite and has been imple­ment­ed with many com­bi­na­tions of net­work and data link lay­er tech­nolo­gies, such as IPv4, Chaos­net and DEC­net using IEEE 802 stan­dards, FDDI, X.25 and Frame Relay amongst others.


COMTRADE file — IEEE C37.111‑1999

The IEEE C37.111‑1999 Com­trade file is a stan­dard­ized for­mat for record­ing and exchang­ing tran­sient wave­form data from pow­er sys­tems. It is used by util­i­ties and man­u­fac­tur­ers to exchange data relat­ed to pow­er sys­tem faults and dis­tur­bances for analy­sis, test­ing, and sim­u­la­tion purposes.

The Com­trade file con­tains time-stamped volt­age and cur­rent sam­ples that rep­re­sent the behav­ior of the pow­er sys­tem dur­ing a dis­tur­bance. The data is typ­i­cal­ly cap­tured by pro­tec­tive relays or oth­er mon­i­tor­ing equip­ment and is used to ana­lyze and diag­nose faults and dis­tur­bances in the pow­er system.

The Com­trade file for­mat was devel­oped by the Insti­tute of Elec­tri­cal and Elec­tron­ics Engi­neers (IEEE) and is wide­ly used in the pow­er indus­try. It pro­vides a stan­dard­ized way to exchange data between dif­fer­ent man­u­fac­tur­ers’ equip­ment and allows for eas­i­er data analy­sis and com­par­i­son across dif­fer­ent pow­er systems.



DLMS/COSEM (or IEC 62056) is the main glob­al stan­dard for smart ener­gy meter­ing, con­trol and man­age­ment. It includes spec­i­fi­ca­tions for media-spe­cif­ic com­mu­ni­ca­tion pro­files, an object-ori­ent­ed data mod­el and an appli­ca­tion lay­er protocol.


Dis­trib­uted Net­work Pro­to­col 3 (DNP3) is a set of com­mu­ni­ca­tions pro­to­cols used between com­po­nents for automa­tion sys­tems in elec­tric, indus­tri­al and water sectors.

It is a key pro­to­col in SCADA sys­tems, where it is pri­mar­i­ly used for com­mu­ni­ca­tions between a mas­ter sta­tion and RTUs or IEDs.


eIoT — Energy IoT

EThe Ener­gy IoT (eIoT) is a rapid­ly grow­ing area of IoT (Inter­net of Things) that focus­es on the use of con­nect­ed devices and sen­sors to improve ener­gy effi­cien­cy, reduce waste, and pro­mote sus­tain­abil­i­ty in the ener­gy sec­tor. The eIoT encom­pass­es a wide range of tech­nolo­gies and appli­ca­tions, includ­ing smart grids, smart homes, smart build­ings, and indus­tri­al IoT.
One of the key ben­e­fits of the eIoT is its abil­i­ty to pro­vide real-time data and insights about ener­gy con­sump­tion and pro­duc­tion. By col­lect­ing data from con­nect­ed devices and sen­sors, ener­gy com­pa­nies can gain a bet­ter under­stand­ing of how ener­gy is being used and where there may be oppor­tu­ni­ties for improve­ment. This can help to reduce waste, low­er costs, and improve the reli­a­bil­i­ty and resilience of ener­gy sys­tems.
The eIoT can also help to pro­mote the use of renew­able ener­gy sources, such as solar and wind pow­er. By using con­nect­ed devices and sen­sors to mon­i­tor ener­gy pro­duc­tion and con­sump­tion, ener­gy com­pa­nies can bet­ter inte­grate renew­able ener­gy sources into the grid and opti­mize their use.
In addi­tion to its ben­e­fits for ener­gy com­pa­nies, the eIoT can also have sig­nif­i­cant ben­e­fits for con­sumers. By using con­nect­ed devices and sen­sors in homes and build­ings, con­sumers can gain greater con­trol over their ener­gy usage and reduce their ener­gy bills. For exam­ple, smart ther­mostats can auto­mat­i­cal­ly adjust the tem­per­a­ture of a home or build­ing based on occu­pan­cy and weath­er con­di­tions, reduc­ing ener­gy waste and improv­ing comfort.


Encryp­tion, from ancient Greek Kryp­tós (“hid­den”), is the art of hid­ing writ­ten mes­sages by apply­ing a giv­en math­e­mat­i­cal algo­rithm. Encryp­tion seeks many objec­tives, such as;

  • Con­fi­den­tial­i­ty: the orig­i­nal mes­sage (“plain text”) should not be under­stood by any­body else than the legit­i­mate destination
  • Authen­ti­ca­tion; the receiv­er wants to make sure that the mes­sage comes from an autho­rised source. This is impor­tant, for exam­ple in a GOOSE mes­sage trip­ping a break­er (who sent it? Is the trans­mit­ter real­ly autho­rised to trip a break­er or not?)
  • Integri­ty: the receiv­er wants to make sure that the orig­i­nal mes­sage has not been mod­i­fied by a man-in-the-mid­dle attack

All  encryp­tion algo­rithms can be clas­si­fied under the fol­low­ing two categories;

  • Sym­met­ri­cal encryption
  • Asym­met­ri­cal encryption

Encryp­tion for Smart Grids is defined in IEC62351 series (Sub­sta­tions), IEC 62056 (Smart Meters) and NERC-CIP, among oth­ers. Usu­al­ly a com­bi­na­tion of asym­met­ri­cal and sym­met­ri­cal algo­rithms is used to ben­e­fit from the advan­tages of both categories.

ESS — Energy Storage System

An ener­gy stor­age sys­tem (ESS) is a tech­nol­o­gy that is designed to store ener­gy and release it when it is need­ed. ESSs are becom­ing increas­ing­ly impor­tant as renew­able ener­gy sources, such as solar and wind pow­er, become more wide­ly used. These sources of ener­gy are inter­mit­tent, mean­ing that they can’t always gen­er­ate elec­tric­i­ty when it is need­ed. ESSs can help to bal­ance the sup­ply and demand of elec­tric­i­ty by stor­ing excess ener­gy when it is gen­er­at­ed and releas­ing it when it is need­ed.
One of the most known meth­ods is bat­tery stor­age, which involves stor­ing elec­tri­cal ener­gy in bat­ter­ies, which can be charged and dis­charged as need­ed. Bat­tery stor­age sys­tems can be used in homes, busi­ness­es, and util­i­ty-scale applications.


Eth­er­net is a fam­i­ly of wired com­put­er net­work­ing tech­nolo­gies com­mon­ly used in local area net­works (LAN) and also wide area net­works (WAN).

Over time, Eth­er­net has large­ly replaced com­pet­ing wired LAN tech­nolo­gies by pro­vid­ing high­er bit rates, a greater num­ber of nodes, and longer link dis­tances and decent back­ward compatibility.


100BASE-TX — Fast Ethernet 

100BASE-TX is the most com­mon Fast Eth­er­net phys­i­cal lay­er, trans­mit­ting data through two twist­ed wire-pairs (one for each direc­tion), which pro­vide full duplex oper­a­tion with 100 Mbit/s of through­put in each direction.

The cabling dis­tance is lim­it­ed to 100 metres (328 ft) for each net­work segment.

FTP — File Transfer Protocol

The File Trans­fer Pro­to­col (FTP) stan­dard defines an appli­ca­tion lay­er net­work pro­to­col to trans­fer files from a serv­er to a client on a com­put­er network.

FTP is based on a client-serv­er mod­el archi­tec­ture using sep­a­rate con­trol and data con­nec­tions between client and server.

FX100 Ethernet

Fast Eth­er­net is the name of the exten­sion to 100 Mbit/s Eth­er­net net­work to 10 Mbit/s. This is the IEEE 802.3u work­ing group that is at the ori­gin. Access tech­nique is the same as in the Eth­er­net Ver­sion 10 Mbit/s, but at a speed mul­ti­plied by 10. trans­port­ed frames are iden­ti­cal. This increase in speed may con­flict with the wiring sys­tem and the pos­si­bil­i­ty or not there such impor­tant tran­sit flows.



A com­mu­ni­ca­tion gate­way is a hard­ware or soft­ware device that serves as an inter­me­di­ary between dif­fer­ent com­mu­ni­ca­tion pro­to­cols, allow­ing them to exchange infor­ma­tion and data. Its pri­ma­ry func­tion is to enable inter­op­er­abil­i­ty and seam­less com­mu­ni­ca­tion between dis­parate sys­tems that may use dif­fer­ent com­mu­ni­ca­tion pro­to­cols, data for­mats, or technologies.

In sub­sta­tion automa­tion is very com­mon the use of gate­ways to col­lect infor­ma­tion from IEDs and send it to the con­trol cen­ter or the site RTU

Grid Codes

Grid codes are a set of tech­ni­cal require­ments and stan­dards that gov­ern the oper­a­tion and inter­con­nec­tion of pow­er gen­er­a­tion and dis­tri­b­u­tion sys­tems to the elec­tric grid. Grid codes are devel­oped and enforced by reg­u­la­to­ry author­i­ties and sys­tem oper­a­tors to ensure the safe, reli­able, and effi­cient oper­a­tion of the pow­er system.

Grid codes typ­i­cal­ly cov­er a wide range of tech­ni­cal aspects relat­ed to the con­nec­tion and oper­a­tion of pow­er gen­er­a­tion and dis­tri­b­u­tion sys­tems, including:

  1. Pow­er qual­i­ty: Grid codes define the min­i­mum stan­dards for volt­age and fre­quen­cy sta­bil­i­ty, har­mon­ics, and oth­er para­me­ters that affect the qual­i­ty of the pow­er sup­plied to the grid.

  2. Pro­tec­tion: Grid codes spec­i­fy the pro­tec­tion schemes and set­tings required to ensure the safe and reli­able oper­a­tion of the pow­er sys­tem, includ­ing mea­sures to pre­vent faults and pro­tect equip­ment from damage.

  3. Con­trol and mon­i­tor­ing: Grid codes require the use of spe­cif­ic con­trol and mon­i­tor­ing sys­tems to ensure the sta­bil­i­ty and reli­a­bil­i­ty of the pow­er sys­tem, includ­ing the use of auto­mat­ic gen­er­a­tion con­trol (AGC), fre­quen­cy con­trol, and oth­er measures.

  4. Con­nec­tion require­ments: Grid codes spec­i­fy the tech­ni­cal require­ments for con­nect­ing pow­er gen­er­a­tion and dis­tri­b­u­tion sys­tems to the grid, includ­ing the require­ments for equip­ment, pro­tec­tion, and con­trol systems.

Grid codes are impor­tant for ensur­ing the safe and reli­able oper­a­tion of the pow­er sys­tem, and for enabling the inte­gra­tion of renew­able ener­gy sources and oth­er dis­trib­uted gen­er­a­tion sys­tems. Com­pli­ance with grid codes is typ­i­cal­ly manda­to­ry for all pow­er gen­er­a­tion and dis­tri­b­u­tion sys­tems con­nect­ed to the grid.


HTTP — Hypertext Transfer Protocol

The Hyper­text Trans­fer Pro­to­col (HTTP) is a stan­dard­ized appli­ca­tion lay­er pro­to­col for dis­trib­uted and col­lab­o­ra­tive, hyper­me­dia infor­ma­tion systems.

Along­side HTML, HTTP facil­i­tat­ed the devel­op­ment of orig­i­nal World Wide Web, the first inter­ac­tive, text-based web browser.

HTTPS — Hypertext Transfer Protocol Secure

HTTPS (Secure HTTP) is the cyber­se­cured ver­sion of HTTP, Hyper Text Trans­fer Pro­to­col. Its pur­pose is to encrypt the con­tents of a web page so that its trans­mis­sion between client and serv­er ben­e­fits from con­fi­den­tial­i­ty, authen­ti­ca­tion and integri­ty. In fact HTTPS is HTTP (Appli­ca­tion Lay­er) com­bined with TLS (Trans­port Lay­er Secu­ri­ty), an encryp­tion lay­er that makes uses of encryp­tion algorithms.

HSR — High-availability Seamless Redundancy

HSR (High-avail­abil­i­ty Seam­less Redun­dan­cy) is a redun­dan­cy pro­to­col for Eth­er­net net­works requir­ing short reac­tion times and high avail­abil­i­ty, as for exam­ple pro­tec­tion sys­tems at elec­tri­cal substations.

Unlike com­mon redun­dan­cy pro­to­cols like RSTP, HSR reacts to any net­work com­po­nent fail­ures seam­less­ly (with­out recov­ery time) and is invis­i­ble to the application.



ICCP (Inter-Con­trol Cen­ter Com­mu­ni­ca­tions Pro­to­col) is a stan­dard pro­to­col for com­mu­ni­ca­tions between con­trol cen­ters, which is part of the IEC 60870–6 stan­dard under the name of TASE.2 Tele­con­trol Appli­ca­tion Ser­vice Ele­ment 2.

It is being used around the world to exchange data over wide area net­works (WANs) between grid oper­a­tors, util­i­ties, vir­tu­al pow­er plants, region­al con­trol cen­ters and oth­er generators.

IEC 60870–5‑104 // IEC104

IEC 60870–5 is a pro­to­col stan­dard for tele­con­trol, telepro­tec­tion, and oth­er telecom­mu­ni­ca­tion func­tions for elec­tric pow­er systems.

IEC 60870–5‑104 (short IEC-104) is a com­pan­ion stan­dard defin­ing how to extend the IEC 60870–5‑101 pro­to­col to gain net­work access using stan­dard trans­port profiles.

IEC 60870–5‑101/104 DPS — Double Point State

DPS, or Dou­ble Point State, is a data type defined in the IEC 60870–5‑104 com­mu­ni­ca­tion pro­to­col, which is used for exchang­ing data between super­vi­so­ry con­trol and data acqui­si­tion (SCADA) sys­tems and remote ter­mi­nal units (RTUs) or intel­li­gent elec­tron­ic devices (IEDs).

In IEC 60870–5‑104, DPS is used to rep­re­sent the sta­tus of a bina­ry sig­nal, such as a switch or valve, that can be in one of two pos­si­ble states: ON or OFF. DPS uses two bits to rep­re­sent each bina­ry sig­nal, allow­ing for four pos­si­ble states: ON, OFF, Inde­ter­mi­nate, or Error.

The four pos­si­ble states of DPS are defined as follows:

  • ON: The bina­ry sig­nal is in the ON state.
  • OFF: The bina­ry sig­nal is in the OFF state.
  • Inde­ter­mi­nate: The sta­tus of the bina­ry sig­nal is uncer­tain or undefined.
  • Error: An error con­di­tion has occurred while read­ing or writ­ing the bina­ry signal.

DPS is com­mon­ly used in SCADA sys­tems and oth­er indus­tri­al appli­ca­tions to mon­i­tor and con­trol the sta­tus of bina­ry sig­nals in remote devices. The use of DPS in IEC 60870–5‑104 ensures that the sta­tus of bina­ry sig­nals can be accu­rate­ly and reli­ably com­mu­ni­cat­ed between SCADA sys­tems and RTUs or IEDs, allow­ing for effec­tive con­trol and mon­i­tor­ing of indus­tri­al processes.

IEC 61850 — BRCB/URCB — Buffered/Unbuffered MMS Reports

IEC 61850 dis­tin­guish­es between buffered and unbuffered report­ing. In unbuffered report­ing events will not be logged and report­ed if the asso­ci­at­ed client for the unbuffered report con­trol block is not con­nect­ed. In the case of buffered report­ing the events will be logged for a spe­cif­ic amount of time and sent lat­er when the client is con­nect­ed again

IEC 61850 — GOOSE

The GOOSE (Gener­ic Object Ori­ent­ed Sub­sta­tion Event) pro­to­col is a com­mu­ni­ca­tion mod­el defined by the IEC 61850 stan­dard, which uses fast and reli­able mech­a­nisms to group any for­mat of data (sta­tus, val­ue) into a data set and trans­mit it through elec­tri­cal net­works with­in 4 milliseconds.

It is most com­mon­ly used for data exchanges between IEDs (IED – Intel­li­gent Elec­tron­ic Device) in elec­tri­cal sub­sta­tions over Ethernet.

IEC 61850 — ICD File 

IED Capa­bil­i­ty Descrip­tion (ICD) files are a spe­cif­ic type of Sub­sta­tion Con­fig­u­ra­tion Lan­guage (SCL) file, con­tain­ing a gener­ic descrip­tion of the whole capa­bil­i­ty range of a giv­en device, includ­ing the func­tions and objects it can support.

The ICD file is usu­al­ly sup­plied by the developer/manufacturer.

IEC 61850 — LN Logical Node 

Log­i­cal nodes or LN (abstract data objects) are the main ele­ments of the vir­tu­al object-ori­ent­ed IEC 61850 mod­el, which con­sists of stan­dard­ized data and data attributes.

The abstract data objects can be mapped to any oth­er pro­to­col, as for exam­ple with the MMS or SMV pro­to­col on an Eth­er­net data frame.

IEC 61850 — MMS Protocol

IEC 61850 MMS (Man­u­fac­tur­ing Mes­sage Spec­i­fi­ca­tion) is a client/server based pro­to­col for com­mu­ni­ca­tions between IEDs (IED – Intel­li­gent Elec­tron­ic Device) and high­er lev­el enti­ties (such as RTUs and SCADAs) over Eth­er­net that is part of the IEC 61850 stan­dard for com­mu­ni­ca­tion tech­nol­o­gy in substations.

It is mapped onto TCP/IP and allows to access the serv­er through its IP address in order to write/read data and exchange files.

IEC 61850 — SCL — Substation Configuration Language

The IEC 61850 stan­dard for sub­sta­tion automa­tion spec­i­fies a stadard­ized sub­sta­tion con­fig­u­ra­tion lan­guage (SCL) to trans­fer device descrip­tions and com­mu­ni­ca­tion para­me­ters amongst dif­fer­ent vendors/manufacturers.

SCL files define sev­er­al capa­bil­i­ty sub­sets for the IED to instan­ti­ate its capabilities.

IEC 62439–3

IEC 62439–3:2016 defines the PRP and HSR stan­dards, which pro­vide seam­less failover against fail­ure of any sin­gle com­po­nent in Eth­er­net networks.

PRP and HSR are appli­ca­tion pro­to­col inde­pen­dent, can be used by most Indus­tri­al Eth­er­net pro­to­cols in the IEC 61784 suite and have been inte­grat­ed in the frame­work of IEC 61850 for sub­sta­tion automation.

IEC 62443

IEC 62443 is an Inter­na­tion­al Stan­dard deal­ing with cyber­se­cu­ri­ty in Indus­tri­al Automa­tion and Con­trol Sys­tems (IACS). While IEC 62351 empha­sizes on encrypt­ing com­mu­ni­ca­tions, IEC 62443 empha­sizes on the device itself and intro­duces require­ments such as a gen­er­alised def­i­n­i­tion of user (so that RBAC applies not only to humans but soft­ware process­es as well); or the require­ment that pass­words be stored in hard­ware, which makes the use of TPM ICs nec­es­sary. From its very def­i­n­i­tion IEC 62443 applies nat­u­ral­ly to RTUs and asso­ci­at­ed equipment.

IEC 62439–3

IEC 62439–3:2016 defines the PRP and HSR stan­dards, which pro­vide seam­less failover against fail­ure of any sin­gle com­po­nent in Eth­er­net networks.

PRP and HSR are appli­ca­tion pro­to­col inde­pen­dent, can be used by most Indus­tri­al Eth­er­net pro­to­cols in the IEC 61784 suite and have been inte­grat­ed in the frame­work of IEC 61850 for sub­sta­tion automation.

IEC 62351

IEC 62351 is a series of Stan­dards deal­ing with Cyber­se­cu­ri­ty in elec­tric­i­ty sys­tems. Devel­oped by IEC TC57 WG15, they aim at improv­ing the dif­fer­ent aspects of Cyber­se­cu­ri­ty in the dif­fer­ent RTUs and IEDs deployed in sub­sta­tions, with parts ded­i­cat­ed to encryp­tion and key exchange in tele­con­trol pro­to­cols (e.g. IEC 60870–5‑104 or DNP3.0), 61850, Smart Meter­ing (DLMS-COSEM), RBAC (Role Based Access Con­trol) and Con­for­mance Test­ing among others. 

IED — Intelligent Electronic Device

In the pow­er sec­tor, intel­li­gent elec­tron­ic devices (IED) are micro­proces­sor based pow­er sys­tem equip­ment, such as cir­cuit break­ers, trans­form­ers and capac­i­tor banks, pro­vid­ing con­trol and automa­tion functions.

IEDs receive and process data from sen­sors and oth­er equip­ment to issue con­trol com­mands or adjust tap poi­si­tions in order to pre­vent fail­ures and main­tain the desired volt­age level.

IP Routing

IP rout­ing encom­pass­es dif­fer­ent method­olo­gies to route Inter­net Pro­to­col (IP) pack­ets with­in and across IP net­works by deter­min­ing a suit­able path to trans­fer net­work pack­ets between source and des­ti­na­tion nodes in and across IP networks.

IP Rout­ing pro­to­cols enable routers to build up a for­ward­ing table that cor­re­lates final des­ti­na­tions with next hop addresses.

Interlocking (network protection scheme)

The inter­lock con­sists of one or more switch­es that pre­vent both main pow­er and gen­er­a­tor pow­er from pow­er­ing the dwelling simul­ta­ne­ous­ly. With­out this safe­guard, both pow­er sources run­ning at once could cause an over­load con­di­tion, or gen­er­a­tor pow­er back-feed onto the main could cause dan­ger­ous volt­age to reach a line­man repair­ing the main feed far out­side the building.


An invert­er is an elec­tron­ic device that con­verts direct cur­rent (DC) into alter­nat­ing cur­rent (AC). It is wide­ly used in var­i­ous appli­ca­tions to change the type of elec­tri­cal pow­er supply..

Invert­ers play a vital role in enabling the use of alter­na­tive ener­gy sources like solar and wind pow­er and are essen­tial in many mod­ern elec­tri­cal systems.

A string invert­er is a type of pho­to­volta­ic (PV) invert­er used in solar pow­er sys­tems. Its pri­ma­ry func­tion is to con­vert the direct cur­rent (DC) elec­tric­i­ty gen­er­at­ed by a string of solar pan­els into alter­nat­ing cur­rent (AC) elec­tric­i­ty suit­able for use in homes or to feed back into the elec­tri­cal grid. While string invert­ers have sev­er­al advan­tages, they also have some lim­i­ta­tions. The per­for­mance of the entire string can be affect­ed if one pan­el in the string is shad­ed or under­per­form­ing, as the invert­er oper­ates at the low­est com­mon denom­i­na­tor. Addi­tion­al­ly, their cen­tral­ized nature can lead to effi­cien­cy loss­es in cas­es where pan­els are not opti­mal­ly ori­ent­ed or par­tial­ly shaded.



MAC — Medium Access Control

The Medi­um Access Con­trol (MAC) sub­lay­er pro­vides flow con­trol and mul­ti­plex­ing for the trans­mis­sion medi­um to con­trol the hard­ware that inter­acts with the wired, optic and also wire­less trans­mis­sion media in the IEEE 802 LAN/MAN data link layer.

The MAC is accom­pa­nied by the LLC sub­lay­er, which pro­vides flow con­trol and mul­ti­plex­ing for the log­i­cal link (i.e. Ether­Type, 802.1Q VLAN tag etc.)


Meter or Energy meter

An ener­gy meter, also known as an elec­tric­i­ty meter or elec­tric meter, is a device used to mea­sure and record the con­sump­tion of elec­tri­cal ener­gy in a res­i­den­tial, com­mer­cial, or indus­tri­al facil­i­ty. These meters are essen­tial for billing pur­pos­es, as they deter­mine the amount of elec­tric­i­ty con­sumed by a cus­tomer, but also for mon­i­tor­ing and con­trol purposes.

Ener­gy meters are an inte­gral part of the elec­tric­i­ty dis­tri­b­u­tion infra­struc­ture, and they play a cru­cial role in the fair and accu­rate billing of elec­tric­i­ty con­sump­tion. The advance­ment of tech­nol­o­gy, par­tic­u­lar­ly with the intro­duc­tion of smart meters, has enabled more effi­cient and trans­par­ent mon­i­tor­ing of elec­tric­i­ty usage, ben­e­fit­ing both util­i­ty com­pa­nies and consumers.

Usu­al­ly, SCADA sys­tems and RTUs con­nect with ener­gy meter using DLMS and IEC 60870–5‑102 protocols

Modbus RTU & TCP

Mod­bus is a com­mu­ni­ca­tions pro­to­col based on master/slave (RTU) or client/server (TCP/IP) archi­tec­tures that can oper­ate on the 1st, 2nd, 7th lev­el of the OSI Model.

Orig­i­nal­ly designed in 1979 by Mod­i­con for its range of PLCs, it is now a de fac­to stan­dard com­mu­ni­ca­tions pro­to­col in the indus­try, becom­ming the most wide­ly avail­able pro­to­col for the con­nec­tion of indus­tri­al elec­tron­ic devices.


MQTT (Mes­sage Queu­ing Teleme­try Trans­port) is a light­weight mes­sag­ing pro­to­col that is designed to be used in con­strained or low-band­width net­works, such as those used in IoT (Inter­net of Things) devices. It is a pub­lish-sub­scribe pro­to­col, where devices or appli­ca­tions can pub­lish mes­sages to a cen­tral bro­ker, which then dis­trib­utes the mes­sages to oth­er devices or appli­ca­tions that have sub­scribed to the same top­ics.
MQTT is designed to be sim­ple, effi­cient, and reli­able, mak­ing it well-suit­ed for use in resource-con­strained envi­ron­ments. It uses a small mes­sage head­er, which min­i­mizes the amount of data that needs to be trans­mit­ted, and it also includes fea­tures such as Qual­i­ty of Ser­vice (QoS) lev­els, which pro­vide dif­fer­ent lev­els of reli­a­bil­i­ty for mes­sage deliv­ery.
MQTT sup­ports a wide range of appli­ca­tions, includ­ing home automa­tion, indus­tri­al con­trol sys­tems, and teleme­try appli­ca­tions. It is used by many IoT plat­forms and is sup­port­ed by a wide range of pro­gram­ming lan­guages and plat­forms, mak­ing it a pop­u­lar choice for build­ing IoT appli­ca­tions.
Over­all, MQTT is a flex­i­ble and reli­able mes­sag­ing pro­to­col that is well-suit­ed for use in IoT and oth­er appli­ca­tions that require effi­cient and reli­able mes­sag­ing in con­strained or low-band­width networks.

Multi-drop Bus

In order to auto­mate, mon­i­tor and con­trol a sub­sta­tion and its intel­li­gent devices in real time from a cen­tral mon­i­tor­ing sta­tion, the sub­sta­tion must be con­nect­ed to a Super­vi­so­ry Con­trol and Data Acqui­si­tion (SCADA) system.

The SCADA pro­vides grid oper­a­tors with an HMI (Human Machine Inter­face) to visu­al­ize col­lect­ed data and facil­i­tate the sub­sta­tion main­te­nance and operation.



North Amer­i­can Elec­tric­i­ty Reli­a­bil­i­ty Cor­po­ra­tion (NERC), and its pre­de­ce­sor North Amer­i­can Elec­tric­i­ty Reli­a­bil­i­ty Coun­cil, is a non-prof­it organ­i­sa­tion whose goal is to ensure the reli­a­bil­i­ty of elec­tric­i­ty sup­ply across North Amer­i­ca by devel­op­ing tech­ni­cal stan­dards for pow­er sys­tem oper­a­tion. NERC devel­oped the so-called CIP (Crit­i­cal Infra­struc­ture Pro­tec­tion), a set of nine stan­dards to imple­ment cyber­se­cu­ri­ty in pow­er sys­tems. NERC-CIP stan­dards cov­er tech­ni­cal and non-tech­ni­cal aspects, such as the use of encryp­tion or per­son­nel aware­ness and train­ing, and have been adopt­ed worl­wide as a ref­er­ence frame­work for cyber­se­cu­ri­ty in pow­er systems.


Network Redundancy

Net­work redun­dan­cy is a method to ensure net­work avail­abil­i­ty, pro­vid­ing failover when a device or net­work path fails or becomes unavailable.

Redun­dan­cy is usu­al­ly achieved by installing addi­tion­al or alter­na­tive net­work devices, com­mu­ni­ca­tion media or equip­ment with­in the net­work infrastructure.

NTP — Network Time Protocol

NTP stands for Net­work Time Pro­to­col, which is a pro­to­col used to syn­chro­nize the clocks of net­worked devices over the Inter­net or oth­er networks.

NTP is designed to pro­vide accu­rate and reli­able time syn­chro­niza­tion for a wide range of appli­ca­tions, includ­ing indus­tri­al con­trol and oth­er time-sen­si­tive sys­tems. NTP works by exchang­ing time syn­chro­niza­tion mes­sages between devices, using a hier­ar­chi­cal sys­tem of time servers to ensure accu­ra­cy and reliability.

NTP is wide­ly used across the Inter­net and oth­er net­works to syn­chro­nize the clocks of devices with a ref­er­ence time source, such as an atom­ic clock or GPS receiv­er. This allows devices to main­tain accu­rate and con­sis­tent time, even in the face of net­work delays and oth­er fac­tors that can affect clock accuracy.

NTP is a key com­po­nent of many mod­ern com­put­er sys­tems and net­works, and is often used in con­junc­tion with oth­er time syn­chro­niza­tion pro­to­cols and tech­nolo­gies to pro­vide a reli­able and accu­rate time source for crit­i­cal applications.


PKI — Public Key Infrastructure

PKI stands for Pub­lic Key Infra­struc­ture, which is a set of tech­nolo­gies, process­es, and poli­cies used to man­age dig­i­tal cer­tifi­cates and pub­lic-key encryp­tion. A PKI enables secure com­mu­ni­ca­tion over untrust­ed net­works by pro­vid­ing a frame­work for ver­i­fy­ing the iden­ti­ty of users, devices, and servers, and for ensur­ing the con­fi­den­tial­i­ty, integri­ty, and authen­tic­i­ty of infor­ma­tion exchanged over the network.

A PKI typ­i­cal­ly con­sists of sev­er­al com­po­nents, including:

  1. Cer­tifi­cate Author­i­ty (CA): A trust­ed third-par­ty that issues dig­i­tal cer­tifi­cates to users and devices, which are used to authen­ti­cate their iden­ti­ty and estab­lish secure communication.
  2. Reg­is­tra­tion Author­i­ty (RA): A com­po­nent that ver­i­fies the iden­ti­ty of users and devices before issu­ing dig­i­tal certificates.
  3. Cer­tifi­cate Repos­i­to­ry: A data­base or direc­to­ry that stores dig­i­tal cer­tifi­cates issued by the CA.
  4. Cer­tifi­cate Revo­ca­tion List (CRL): A list of dig­i­tal cer­tifi­cates that have been revoked or are no longer valid.
  5. Cer­tifi­cate Pol­i­cy: A set of rules and guide­lines that gov­ern the issuance and man­age­ment of dig­i­tal cer­tifi­cates with­in the PKI.

A PKI is wide­ly used in many appli­ca­tions and indus­tries, includ­ing pow­er con­trol, e‑commerce, online bank­ing, and secure email. PKI pro­vides a secure and reli­able method for ver­i­fy­ing the iden­ti­ty of users and devices, and for pro­tect­ing sen­si­tive infor­ma­tion from unau­tho­rized access or interception.

PLC — IEC 61131–3

IEC 61131 is an inter­na­tion­al stan­dard that describes Pro­gram­ma­ble Log­ic Con­trollers, a type of pro­gram­ma­ble indus­tri­al automa­tion sys­tems. IEC 61131 PLC sys­tems embed­ded in RTUs allow the imple­men­ta­tion of cus­tom func­tions by pro­cess­ing dif­fer­ent inputs and gen­er­at­ing outputs.

Com­mon exam­ples are an RTU auto­mat­i­cal­ly con­nect­ing capac­i­tor banks when the reac­tive pow­er exceeds a thresh­old or per­form­ing load shed­ding when the fre­quen­cy devi­ates. The pro­gram itself can be writ­ten in five dif­fer­ent pro­gram­ming lan­guages, described in part 3 of the standard.

PLC accord­ing to IEC61131‑3 is sup­port­ed in all iGrid prod­ucts, includ­ing the iRTU/iGW series and the iCon­trol SCADA system.

Power Plant Controller — PPC

PPC (Pow­er Plant Con­troller) is a con­trol loop that reg­u­lates the amount of ener­gy inject­ed to the grid by a gen­er­a­tion plant, to make sure that com­plies with both the set­points and the grid codes dic­tat­ed by the TSO. The PPC receives the set­point from the TSO del­e­gate office and receives feed­back from a meter installed at the Point of Injection.


PROFIBUS (Process Field Bus) is an open stan­dard for field­bus com­mu­ni­ca­tions in indus­tri­al automa­tion sys­tems that was first pro­mot­ed in Ger­many in 1989.

The now most com­mon­ly found “Profibus DP” pro­vides sim­ple com­mu­ni­ca­tions between Profibus mas­ters and their remote I/O slaves.

Protection Relay

A pro­tec­tion relay is an elec­tron­ic device which con­sti­tutes an an essen­tial com­po­nent in elec­tri­cal pow­er sys­tems, being designed to detect abnor­mal oper­at­ing con­di­tions or faults in the pow­er sys­tem and ini­ti­ate appro­pri­ate actions to pro­tect the equip­ment and ensure the safe­ty and sta­bil­i­ty of the elec­tri­cal network.

The main func­tion of a pro­tec­tion relay is to mon­i­tor elec­tri­cal para­me­ters such as cur­rent, volt­age, fre­quen­cy, pow­er, and oth­er rel­e­vant quan­ti­ties with­in the pow­er sys­tem. When the relay detects a fault or abnor­mal con­di­tion, it sends a sig­nal to the asso­ci­at­ed cir­cuit break­er or oth­er switch­ing devices to iso­late the faulty sec­tion from the rest of the network.

Here are some key fea­tures and func­tions of a pro­tec­tion relay:

  1. Fault Detec­tion: Pro­tec­tion relays con­tin­u­ous­ly mon­i­tor the elec­tri­cal para­me­ters of the pow­er sys­tem. They ana­lyze these para­me­ters and com­pare them to pre­de­fined set­tings to iden­ti­fy abnor­mal con­di­tions, such as short cir­cuits, over­loads, volt­age sags, over­volt­age, under­fre­quen­cy, and oth­er faults. The func­tions exe­cut­ed by the pro­tec­tion relays are defined by stan­dariza­tion bod­ies, like IEEE with its stan­dard IEEE C37.2
  2. Selec­tiv­i­ty and Coor­di­na­tion: Pro­tec­tion relays are designed to pro­vide selec­tiv­i­ty and coor­di­na­tion in the elec­tri­cal net­work. Selec­tiv­i­ty ensures that only the clos­est cir­cuit break­er to the fault loca­tion is tripped, min­i­miz­ing the impact on the rest of the sys­tem. Coor­di­na­tion allows for sequen­tial oper­a­tion of relays and cir­cuit break­ers to iso­late faults in a cas­cad­ing manner.
  3. Relay Log­ic and Algo­rithms: Pro­tec­tion relays employ var­i­ous log­ic schemes and algo­rithms to deter­mine fault con­di­tions accu­rate­ly and reli­ably. These schemes may include time-based, cur­rent-based, or volt­age-based tech­niques to dif­fer­en­ti­ate between fault and nor­mal oper­at­ing conditions.
  4. Com­mu­ni­ca­tion and Inte­gra­tion: Mod­ern pro­tec­tion relays often fea­ture com­mu­ni­ca­tion capa­bil­i­ties, enabling them to exchange infor­ma­tion with oth­er relays, con­trol sys­tems, and mon­i­tor­ing devices, with com­mu­ni­ca­tion pro­to­cols like IEC 61850, DNP3.0 or IEC 60870–5‑103. This facil­i­tates remote mon­i­tor­ing, cen­tral­ized con­trol, and coor­di­nat­ed pro­tec­tion across dif­fer­ent parts of the pow­er system.

PRP — Parallel Redundancy Protocol

PRP (Par­al­lel Redun­dan­cy Pro­to­col) is a redun­dan­cy pro­to­col for Eth­er­net based net­works requir­ing high avail­abil­i­ty and a short switchover time, as for exam­ple pro­tec­tion sys­tems at elec­tri­cal substations.

Unlike com­mon redun­dan­cy pro­to­cols like RSTP, PRP reacts to any net­work com­po­nent fail­ures seam­less­ly (with­out recov­ery time) and is invis­i­ble to the application.

PTP — Precision Time Protocol — IEEE 1588

IEEE 1588 is a stan­dard for pre­ci­sion clock syn­chro­niza­tion of net­worked devices. It is also known as Pre­ci­sion Time Pro­to­col (PTP).

The IEEE 1588 stan­dard pro­vides a mech­a­nism for syn­chro­niz­ing the clocks of devices con­nect­ed over a net­work with sub-microsec­ond accu­ra­cy. This is par­tic­u­lar­ly impor­tant in appli­ca­tions such as indus­tri­al automa­tion, finan­cial trad­ing, telecom­mu­ni­ca­tions, and oth­er real-time sys­tems where accu­rate tim­ing is critical.

The stan­dard defines a pro­to­col that enables devices to syn­chro­nize their clocks to a com­mon ref­er­ence time, known as a grand­mas­ter clock. This is achieved by exchang­ing tim­ing mes­sages between devices over the net­work, and adjust­ing the local clock of each device to align with the grand­mas­ter clock.

IEEE 1588 has sev­er­al dif­fer­ent pro­files, each tai­lored to spe­cif­ic appli­ca­tions and net­work topolo­gies. It is wide­ly used in indus­tri­al con­trol sys­tems, pow­er dis­tri­b­u­tion net­works, and oth­er crit­i­cal infra­struc­ture applications.

PV plant Performance Ratio

The per­for­mance ratio (PR) is a met­ric used to eval­u­ate the effi­cien­cy and per­for­mance of a pho­to­volta­ic (PV) pow­er plant. It rep­re­sents the ratio of the actu­al ener­gy out­put of the PV sys­tem to the the­o­ret­i­cal or expect­ed ener­gy out­put under stan­dard test con­di­tions (STC). The per­for­mance ratio is expressed as a percentage.

The per­for­mance ratio takes into account var­i­ous fac­tors that affect the ener­gy pro­duc­tion of a PV plant, includ­ing sys­tem loss­es, envi­ron­men­tal con­di­tions, and equip­ment per­for­mance. It pro­vides a mea­sure of how effec­tive­ly the PV sys­tem con­verts sun­light into usable electricity.

The Inter­na­tion­al Elec­trotech­ni­cal Com­mis­sion (IEC) defines the IEC 61724 stan­dard which out­lines the pro­ce­dures and guide­lines for the assess­ment of the ener­gy yield of PV sys­tems. This stan­dard pro­vides a frame­work for mea­sur­ing, cal­cu­lat­ing, and report­ing the per­for­mance ratio of a PV plant. It’s worth not­ing that the exact cal­cu­la­tion method­ol­o­gy and para­me­ters for deter­min­ing the per­for­mance ratio may vary slight­ly based on project-spe­cif­ic require­ments and local reg­u­la­tions. How­ev­er, the IEC 61724 stan­dard pro­vides a wide­ly accept­ed frame­work for per­for­mance ratio assess­ment in the PV industry.

The per­for­mance ratio cal­cu­la­tion con­sid­ers sev­er­al fac­tors, including:

1. Sys­tem loss­es: These loss­es include elec­tri­cal loss­es, such as wiring and invert­er loss­es, as well as loss­es due to shad­ing, soil­ing, and mis­match between PV modules.

2. Tem­per­a­ture loss­es: PV mod­ules expe­ri­ence reduced effi­cien­cy as their tem­per­a­ture increas­es. Tem­per­a­ture loss­es account for the decrease in per­for­mance due to high­er mod­ule temperatures.

3. Irra­di­ance loss­es: The actu­al solar irra­di­ance received by the PV mod­ules may devi­ate from the ref­er­ence con­di­tions assumed dur­ing the per­for­mance esti­ma­tion. Irra­di­ance loss­es account for the devi­a­tion between the actu­al and ref­er­ence irra­di­ance levels.

By con­sid­er­ing these fac­tors, the per­for­mance ratio pro­vides an assess­ment of the over­all per­for­mance and effi­cien­cy of the PV sys­tem, tak­ing into account real-world con­di­tions and loss­es. A high­er per­for­mance ratio indi­cates bet­ter per­for­mance and effi­cien­cy of the PV plant.



RBAC — Role Based Access Control

RBAC, or role-based access con­trol, is a method of restrict­ing access to resources based on the roles of indi­vid­ual users with­in an orga­ni­za­tion. In the con­text of IEC 62351, which is a stan­dard for secure com­mu­ni­ca­tion between con­trol sys­tems in the pow­er indus­try, RBAC is used to ensure that only autho­rized users are able to access crit­i­cal sys­tems and data.

IEC 62351 defines a set of secu­ri­ty mech­a­nisms for pro­tect­ing com­mu­ni­ca­tion in pow­er sys­tems, includ­ing RBAC. In this stan­dard, RBAC is imple­ment­ed through the use of roles, which are defined based on the func­tions that users per­form with­in an orga­ni­za­tion. Each role is asso­ci­at­ed with a set of per­mis­sions that dic­tate what actions a user with that role is allowed to perform.

For exam­ple, in a pow­er sys­tem, there might be roles for sys­tem admin­is­tra­tors, oper­a­tors, and engi­neers. The sys­tem admin­is­tra­tor role might have per­mis­sion to mod­i­fy sys­tem con­fig­u­ra­tions, while the oper­a­tor role might only be able to view sys­tem sta­tus and per­form basic oper­a­tions. By using RBAC, orga­ni­za­tions can ensure that users only have access to the resources and data that they need to per­form their spe­cif­ic job func­tions, while also min­i­miz­ing the risk of unau­tho­rized access or data breaches.

RMU — Ring Main Unit

A Ring Main Unit (RMU) is a type of com­pact switchgear used in elec­tri­cal dis­tri­b­u­tion sys­tems. It is typ­i­cal­ly used in medi­um-volt­age pow­er dis­tri­b­u­tion net­works, such as in indus­tri­al plants, com­mer­cial build­ings, and res­i­den­tial areas.

The pri­ma­ry pur­pose of an RMU is to con­trol and pro­tect the dis­tri­b­u­tion of elec­tri­cal pow­er with­in a ring cir­cuit, and they have a cru­cial role in main­tain­ing the reli­a­bil­i­ty and effi­cien­cy of medi­um-volt­age pow­er dis­tri­b­u­tion by pro­vid­ing switch­ing, pro­tec­tion, and con­trol func­tion­al­i­ties in a com­pact and mod­u­lar form.

Here are some key fea­tures and func­tions of an RMU:

  1. Com­pact Design: RMUs are designed to be com­pact, allow­ing for easy instal­la­tion in space-con­strained areas.
  2. Ring Cir­cuit Con­fig­u­ra­tion: RMUs are used in ring dis­tri­b­u­tion net­works where pow­er flows in a looped con­fig­u­ra­tion. This design pro­vides redun­dan­cy and improves the reli­a­bil­i­ty of the dis­tri­b­u­tion system.
  3. Switch­ing and Pro­tec­tion: RMUs con­sist of mul­ti­ple switch­ing devices, such as cir­cuit break­ers and load break switch­es. These devices enable the iso­la­tion, switch­ing, and pro­tec­tion of dif­fer­ent sec­tions of the dis­tri­b­u­tion network.
  4. Fault Detec­tion and Restora­tion: RMUs are equipped with mon­i­tor­ing and con­trol capa­bil­i­ties to detect faults, such as short cir­cuits or over­loads. When a fault occurs, the RMU can iso­late the affect­ed sec­tion of the net­work and restore pow­er to the remain­ing sections.
  5. Volt­age Reg­u­la­tion: Some RMUs also incor­po­rate volt­age reg­u­la­tion capa­bil­i­ties to ensure a sta­ble sup­ply of elec­tri­cal pow­er with­in the dis­tri­b­u­tion network.
  6. Remote Mon­i­tor­ing and Con­trol: Advanced RMUs may have built-in com­mu­ni­ca­tion capa­bil­i­ties, allow­ing for remote mon­i­tor­ing, con­trol, and automa­tion of the dis­tri­b­u­tion system.

RS-232 — TIA/EIA-232

The RS-232 (Rec­om­mend­ed Stan­dard-232) or also known EIA-232 (Elec­tron­ic Indus­tries Alliance-232) is a stan­dard for the ser­i­al trans­mis­sion of data in indus­tri­al applications.

The stan­dard defines the elec­tri­cal char­ac­ter­is­tics and tim­ing of sig­nals, the mean­ing of sig­nals, and the phys­i­cal size and pinout of connectors.

RS-422 — TIA/EIA-422

The RS-422 (Rec­om­mend­ed Stan­dard-422) or also known EIA-422 (Elec­tron­ic Indus­tries Alliance-422) stan­dard defines the char­ac­ter­is­tics of an elec­tri­cal inter­face for ser­i­al com­mu­ni­ca­tions in indus­tri­al con­trol systems.

It was designed to replace the old­er RS-232C stan­dard in order to pro­vide high­er speed (up to 10 Mb/s), bet­ter immu­ni­ty from noise, and longer cable lengths (up to 1,500 meters).

RS-485 — TIA/EIA-485

The RS-485 (Rec­om­mend­ed Stan­dard-485) or also known EIA-485 (Elec­tron­ic Indus­tries Alliance-485) stan­dard defines the char­ac­ter­is­tics of an elec­tri­cal inter­face for ser­i­al com­mu­ni­ca­tions in indus­tri­al con­trol systems.

In con­trast to the old­er RS-232, it allows to bal­ance elec­tri­cal sig­nals and con­nect mul­ti­ple device to the net­work, which can stretch over longer dis­tances and harsh­er environments.


RSTP stands for “Rapid Span­ning Tree Pro­to­col.” It is a net­work pro­to­col used in Eth­er­net net­works to pre­vent loops in the net­work topol­o­gy and ensure that data is for­ward­ed along the most effi­cient path. RSTP is an improve­ment over the orig­i­nal Span­ning Tree Pro­to­col (STP) and offers faster con­ver­gence times, mak­ing it more suit­able for mod­ern net­works where rapid changes in the net­work topol­o­gy can occur.

Here are the key fea­tures and char­ac­ter­is­tics of RSTP:

  1. Loop Pre­ven­tion: RST­P’s pri­ma­ry func­tion is to pre­vent loops in Eth­er­net net­works. Loops can lead to broad­cast storms and net­work insta­bil­i­ty, so RSTP ensures that there is a loop-free path in the net­work by selec­tive­ly block­ing cer­tain net­work links.

  2. Faster Con­ver­gence: One of the sig­nif­i­cant improve­ments of RSTP over STP is its abil­i­ty to con­verge quick­ly when there are changes in the net­work topol­o­gy. Tra­di­tion­al STP can take sev­er­al sec­onds to sev­er­al min­utes to recon­fig­ure after a link fail­ure or net­work change, while RSTP typ­i­cal­ly con­verges in just a few seconds.

  3. Port Roles: RSTP defines dif­fer­ent roles for net­work ports, includ­ing Root, Des­ig­nat­ed, Alter­nate, and Back­up ports. These roles deter­mine which ports are active­ly for­ward­ing traf­fic and which are in stand­by mode, ready to take over if a fail­ure occurs.

  4. Bridge Pro­to­col Data Units (BPDU): RSTP uses BPDU mes­sages to exchange infor­ma­tion between switch­es in the net­work. These mes­sages are used to elect a Root Bridge (the cen­tral switch in the span­ning tree) and deter­mine the best path to reach the Root Bridge.

  5. Port States: RSTP defines sev­er­al port states, including:

    • Block­ing: Ports in this state do not for­ward traf­fic but lis­ten to BPDU mes­sages to deter­mine the net­work topology.
    • Lis­ten­ing: Ports in this state are tran­si­tion­ing to the For­ward­ing state. They still do not for­ward data frames but lis­ten for poten­tial net­work changes.
    • Learn­ing: Ports in this state con­tin­ue to lis­ten for net­work changes and also learn MAC address­es from incom­ing frames.
    • For­ward­ing: Ports in this state active­ly for­ward data frames.
  6. Topol­o­gy Changes: RSTP is designed to react quick­ly to changes in the net­work, such as link fail­ures or addi­tions. When a topol­o­gy change occurs, RSTP recal­cu­lates the span­ning tree and con­verges rapid­ly to a new sta­ble state.

  7. Com­pat­i­bil­i­ty: RSTP is back­ward com­pat­i­ble with STP. It can oper­ate in a mixed net­work where some switch­es are run­ning tra­di­tion­al STP while oth­ers are run­ning RSTP.

  8. 802.1Q VLANs: RSTP is often used in con­junc­tion with VLANs (Vir­tu­al LANs) to cre­ate sep­a­rate broad­cast domains with­in a sin­gle phys­i­cal net­work. RSTP can work with 802.1Q VLAN tag­ging to ensure loop-free topolo­gies with­in each VLAN.

RSTP has become the pre­ferred choice for loop pre­ven­tion and net­work sta­bil­i­ty in Eth­er­net net­works due to its faster con­ver­gence times and improved effi­cien­cy com­pared to tra­di­tion­al STP. It is wide­ly used in mod­ern net­work­ing equip­ment and is con­sid­ered a stan­dard pro­to­col for man­ag­ing net­work topolo­gies in Eth­er­net-based LANs.

RTU — Remote Terminal Unit

RTU most com­mon­ly stands for Remote Ter­mi­nal Unit, but is some­times also used as an abbre­vi­a­tion for Remote Teleme­try Unit or Remote Tele­con­trol Unit.

RTUs are devices that rely on micro­proces­sors and com­mu­ni­ca­tion inter­faces to auto­mat­i­cal­ly mon­i­tor and con­trol field devices and estab­lish a bridge to the plant con­trol or SCADA (super­vi­so­ry con­trol and data acqui­si­tion) systems.



SAI­Di and SAIFI are reli­a­bil­i­ty index­es defined in IEEE 1366 and intend­ed to mea­sure the Qual­i­ty of Ser­vice of elec­tric­i­ty sup­ply. SAIDI (Sys­tem Aver­age Inter­rup­tion Fre­quen­cy Index) mea­sures how often elec­tric­i­ty sup­ply is inter­rupt­ed and how many cus­tomers the inter­rup­tions affect. SAIDI (Sys­tem Aver­age Inter­rup­tion Dura­tion Index) mea­sures the time dura­tion of the inter­rup­tions. Very often SAIDI and SAIFI have to meet max­i­mum val­ues dic­tat­ed by the reg­u­la­tor, and in some coun­tries it is com­pul­so­ry by Law that SAIDI/SAIFI cal­cu­la­tion be sup­port­ed by a SCADA sys­tem (e.g. Spain).

Sampled Values in IEC 61850

Sam­pled Val­ues are one type of Eth­er­nent mes­sage used in dig­i­tal sub­sta­tions, used to trans­mit infor­ma­tion of ana­logue nature in dig­i­tal for­mat. A typ­i­cal appli­ca­tion is mea­sur­ing AC ana­logue cur­rents and volt­ages; the cur­rent and volt­age are mea­sured with current/voltage trans­form­ers and deliv­ered to a merg­ing unit that will sam­ple them at a giv­en samplig rate and gen­er­ate the cor­re­spond­ing Sam­pled Val­ues mes­sages. These sam­pled val­ues mes­sages are then pub­lished in a mul­ti­cast Eth­er­net mes­sage in the process bus of the sub­sta­tion LAN so that all IEDs need­ing this infor­ma­tion may sub­scribe to it and receive it (for exam­ple pro­tec­tion relays). Sam­pled val­ues are described in detail in IEC 61850–9‑2 (“Sam­pled Val­ues over ISO/IEC 802.3”) and IEC 61869–9 (“Dig­i­tal Inter­face for Instru­ment Transformers”).

SCADA — Supervisory Control and Data Acquisition

Super­vi­so­ry con­trol and data acqui­si­tion (SCADA) sys­tems col­lect, mon­i­tor and process real-time data to:

  • Auto­mate and con­trol indus­tri­al process­es remote­ly or locally
  • Pro­vide a human-machine inter­face (HMI) to direct­ly inter­act with devices such as relays, sen­sors, gen­er­a­tors, pumps, valves and others
  • Record events and auto­mate reporting

Secure Boot

HTTPS (Secure HTTP) is the cyber­se­cured ver­sion of HTTP, Hyper Text Trans­fer Pro­to­col. Its pur­pose is to encrypt the con­tents of a web page so that its trans­mis­sion between client and serv­er ben­e­fits from con­fi­den­tial­i­ty, authen­ti­ca­tion and integri­ty. In fact HTTPS is HTTP (Appli­ca­tion Lay­er) com­bined with TLS (Trans­port Lay­er Secu­ri­ty), an encryp­tion lay­er that makes uses of encryp­tion algorithms.


Sequence of events record­ing (SER) is per­formed by micro­proces­sor based sys­tems, which mon­i­tor col­lect­ed data inputs and record the time and sequences of the changes.

Sequence of events recorders rely on exter­nal time sources such as GPS or radio clocks to record the exact time of state of each change.

SNTP — Simple Network Time Protocol

SNTP stands for Sim­ple Net­work Time Pro­to­col, which is a sim­pli­fied ver­sion of the Net­work Time Pro­to­col (NTP). Like NTP, SNTP is a pro­to­col used to syn­chro­nize the clocks of com­put­ers or oth­er net­worked devices over the Inter­net or oth­er networks.

SNTP is designed to pro­vide basic time syn­chro­niza­tion ser­vices with low­er over­head and few­er fea­tures than NTP. SNTP is often used in sit­u­a­tions where a high degree of accu­ra­cy is not required, or where the net­work infra­struc­ture may not be able to sup­port the more com­plex fea­tures of NTP.

While SNTP pro­vides less pre­ci­sion than NTP, it still pro­vides accu­rate time syn­chro­niza­tion with­in a few hun­dred mil­lisec­onds. SNTP uses the same time syn­chro­niza­tion mes­sages and algo­rithms as NTP, but with few­er options and set­tings. SNTP can also syn­chro­nize time with NTP servers, allow­ing devices that sup­port SNTP to take advan­tage of the more accu­rate time sources avail­able with NTP.

SNTP is com­mon­ly used in small net­works or embed­ded sys­tems, where the resources avail­able for time syn­chro­niza­tion are lim­it­ed. SNTP is also used in Inter­net of Things (IoT) devices, net­worked sen­sors, and oth­er low-pow­er or low-band­width appli­ca­tions, where the over­head of NTP would be too high.


Secure Shell is a secure client-serv­er admin­is­tra­tion pro­to­col which allows remote access to IEDs through an authen­ti­ca­tion mech­a­nism. This pro­to­col was cre­at­ed as a secure replace­ment for Tel­net and makes use of both asym­met­ric and sym­met­ric encryp­tion algo­rithms with 128 bit keys. SSH is an essen­tial com­po­nent of cyber­se­cu­ri­ty and is imple­ment­ed in all iRTU/iGW series for secure access to the devices.


A syn­chrocheck is a pro­tec­tive relay func­tion used in pow­er sys­tems to detect and pre­vent dam­age to gen­er­a­tors and oth­er equip­ment dur­ing syn­chro­niza­tion. Syn­chro­niza­tion is the process of con­nect­ing a gen­er­a­tor to the elec­tri­cal grid, and it is crit­i­cal to ensure that the volt­age and fre­quen­cy of the gen­er­a­tor match those of the grid before it is con­nect­ed. If there is a mis­match, it can cause severe dam­age to the gen­er­a­tor and oth­er equipment.

A syn­chrocheck relay is designed to detect the dif­fer­ence in volt­age and fre­quen­cy between the gen­er­a­tor and the grid. It com­pares the volt­age and fre­quen­cy sig­nals from the gen­er­a­tor and the grid and ensures that they are with­in accept­able lim­its before allow­ing the gen­er­a­tor to be syn­chro­nized with the grid. If there is a mis­match in volt­age or fre­quen­cy, the syn­chrocheck relay will pre­vent the gen­er­a­tor from being con­nect­ed to the grid.

In addi­tion to pre­vent­ing dam­age to the equip­ment, syn­chrocheck relays also help to ensure a smooth and sta­ble trans­fer of pow­er from the gen­er­a­tor to the grid. They are an impor­tant com­po­nent of the pro­tec­tive relay sys­tem used in pow­er systems.



ICCP (Inter-Con­trol Cen­ter Com­mu­ni­ca­tions Pro­to­col) is a stan­dard pro­to­col for com­mu­ni­ca­tions between con­trol cen­ters, which is part of the IEC 60870–6 stan­dard under the name of TASE.2 Tele­con­trol Appli­ca­tion Ser­vice Ele­ment 2.

It is being used around the world to exchange data over wide area net­works (WANs) between grid oper­a­tors, util­i­ties, vir­tu­al pow­er plants, region­al con­trol cen­ters and oth­er generators.

TOU — Time Of Use

Time of Use (TOU) is a pric­ing mod­el used by util­i­ty com­pa­nies to charge cus­tomers dif­fer­ent rates for elec­tric­i­ty based on the time of day and the day of the week. Under this pric­ing mod­el, elec­tric­i­ty is more expen­sive dur­ing times of high demand and less expen­sive dur­ing times of low demand.
Typ­i­cal­ly, TOU pric­ing plans involve three dif­fer­ent rate peri­ods: peak, off-peak, and shoul­der. Peak peri­ods are usu­al­ly dur­ing the hours of high­est demand, which can vary depend­ing on the region and the sea­son. Off-peak peri­ods are typ­i­cal­ly dur­ing the night or ear­ly morn­ing, when demand is low. Shoul­der peri­ods are the peri­ods between peak and off-peak times when demand is start­ing to increase or decrease.
Cus­tomers who par­tic­i­pate in TOU pric­ing plans can save mon­ey by shift­ing their ener­gy usage to off-peak times when elec­tric­i­ty rates are low­er. For exam­ple, cus­tomers may choose to run their wash­ing machine or dish­wash­er dur­ing off-peak times to take advan­tage of low­er rates. Some cus­tomers may also choose to install ener­gy stor­age sys­tems or solar pan­els to gen­er­ate their own elec­tric­i­ty dur­ing peak times and avoid high­er rates.
TOU pric­ing plans are becom­ing increas­ing­ly pop­u­lar as more util­i­ty com­pa­nies seek to encour­age ener­gy con­ser­va­tion and the use of renew­able ener­gy sources. They can also help to reduce the need for expen­sive and pol­lut­ing peak­er plants, which are used to meet peak demand.

TCP — Transmission Control Protocol

The Trans­mis­sion Con­trol Pro­to­col (TCP) is one of the main pro­to­cols of the Inter­net pro­to­col suite pro­vid­ing reli­able, ordered, and error-checked byte stream deliv­er­ies between host­ing appli­ca­tions com­mu­ni­cat­ing through an IP network.

Locat­ed in the Trans­port Lay­er of the TCP/IP suite, major inter­net appli­ca­tions such as the World Wide Web, email, SSL/TLS and file trans­fers rely on or run on top of TCP.

TPM — Trusted Platform Modules

TPM stands for Trust­ed Plat­form Mod­ule. It is a hard­ware-based secu­ri­ty solu­tion that pro­vides a secure foun­da­tion for var­i­ous secu­ri­ty func­tions such as authen­ti­ca­tion, encryp­tion, and key management.

A TPM is a microchip that is installed on the RTU’s moth­er­board and it is designed to work with the device’s oper­at­ing sys­tem to pro­vide a secure envi­ron­ment for sen­si­tive data and operations.

The TPM gen­er­ates and stores cryp­to­graph­ic keys, which can be used for a vari­ety of secu­ri­ty pur­pos­es, such as encrypt­ing data or ver­i­fy­ing the integri­ty of the sys­tem. The TPM can also be used for secure boot, which ensures that the sys­tem only boots from trust­ed sources, and for mea­sur­ing the integri­ty of the sys­tem at boot time.

TPMs are com­mon­ly used in enter­prise envi­ron­ments to pro­tect sen­si­tive data and ensure com­pli­ance with secu­ri­ty reg­u­la­tions. They can also be used in con­sumer devices, such as lap­tops and smart­phones, to pro­vide enhanced secu­ri­ty for per­son­al data and transactions.

One of the key com­po­nents of the IEEE 62443 stan­dard is the use of hard­ware-based secu­ri­ty solu­tions, such as Trust­ed Plat­form Mod­ules (TPMs), to pro­tect sen­si­tive data and oper­a­tions. TPMs can be used to secure indus­tri­al automa­tion and con­trol sys­tems (IACS) devices by pro­vid­ing a trust­ed com­put­ing envi­ron­ment, ensur­ing the integri­ty of the sys­tem, and pro­tect­ing cryp­to­graph­ic keys and oth­er sen­si­tive information.

In par­tic­u­lar, the IEEE 62443–2‑4 stan­dard includes rec­om­men­da­tions for the use of TPMs to imple­ment secure boot and to pro­tect the con­fi­den­tial­i­ty and integri­ty of IACS data. The stan­dard rec­om­mends that IACS devices should have a hard­ware-based root of trust, such as a TPM, to ensure that the device boots from a trust­ed source and that the integri­ty of the sys­tem is main­tained through­out its operation.



UDP (acronym for User Data­gram Pro­to­col) is a lay­er 4 trans­port pro­to­col com­mon­ly used in IP net­works. Unlike TCP (Trans­mis­sion Con­trol Pro­to­col), UDP is a con­nec­tion­less pro­to­col, there is no con­nec­tion set­up or con­nec­tion release. This makes it very ade­quate for the trans­port of short, urgent or spon­ta­neous mes­sages, like SNMP; or when retrans­mis­sion is not fea­si­ble, like for exam­ple VoIP. UDP is used in some DNP3.0 pro­files, spe­cial­ly in mobile net­works, at the expense of less effi­cient han­dling of lost packets.


VLAN — Virtual Local Area Network

Vir­tu­al Local Area Net­work (VLAN) is a is a sub­net­work which can group togeth­er col­lec­tions of devices that are con­nect­ed to sep­a­rate phys­i­cal LANs.

VLANs allow net­work admin­is­tra­tors to par­ti­tion a sin­gle switched net­work in order to keep net­work appli­ca­tions sep­a­rate despite being con­nect­ed to the same phys­i­cal net­work, with­out requir­ing new cabling or major changes in the cur­rent net­work infrastructure.

VPN — Virtual Private Network

VPN (acronym for Vir­tu­al Pri­vate Net­work) is a com­mu­ni­ca­tions tech­nol­o­gy that allows client-serv­er secure com­mu­ni­ca­tion over unse­cure chan­nels. A com­mon exam­ple is remote access to a sub­sta­tion over an unse­cure com­mu­ni­ca­tions net­work, e.g. a pub­lic tele­com oper­a­tor. Both the client attempt­ing to access and IED serv­er at the sub­sta­tion must use a VPN soft­ware with embed­ded encryp­tion algo­rithms that pro­vide user authen­ti­ca­tion, data con­fi­den­tial­i­ty and data integrity.


XMPP — Extensible Messaging and Presence Protocol

XMPP (Exten­si­ble Mes­sag­ing and Pres­ence Pro­to­col) is a pro­to­col for real-time com­mu­ni­ca­tion, mes­sag­ing, and pres­ence infor­ma­tion exchange over the inter­net. It is an open-stan­dard tech­nol­o­gy used for instant mes­sag­ing, voice and video calls, and online pres­ence infor­ma­tion.
XMPP was ini­tial­ly devel­oped for use in the Jab­ber instant mes­sag­ing sys­tem, but it has since become a wide­ly used pro­to­col for real-time com­mu­ni­ca­tion and mes­sag­ing appli­ca­tions. It uses XML for mes­sage for­mat­ting and is designed to be exten­si­ble, mean­ing that it can be cus­tomized and adapt­ed to suit dif­fer­ent appli­ca­tions and use cas­es.
XMPP is decen­tral­ized, mean­ing that it does not rely on a cen­tral serv­er to route mes­sages between users. Instead, it uses a fed­er­at­ed archi­tec­ture, where servers can com­mu­ni­cate with each oth­er to route mes­sages and main­tain pres­ence infor­ma­tion. This makes it a more resilient and scal­able pro­to­col than some cen­tral­ized mes­sag­ing sys­tems.
XMPP is used by a vari­ety of appli­ca­tions, includ­ing instant mes­sag­ing clients, social net­work­ing plat­forms, and Inter­net of Things (IoT) devices. It is also used in some enter­prise mes­sag­ing sys­tems and as the basis for some video con­fer­enc­ing and col­lab­o­ra­tion tools.

iGrid Solutions and Applications

Automation with IEC 61850 

The IEC 61850 stan­dard is enabling new opor­tu­ni­ties for ven­dor inter­op­er­abil­i­ty and advanced sub­sta­tion automa­tion. Find out how you can take advan­tage of IEC 61850 with easy-to-use and adapt­able solu­tions for a sim­ple migra­tion or retrofit.

HV Substation Automation

Pow­er­ful sub­sta­tion automa­tion sys­tems often han­dle numer­ous com­mu­ni­ca­tion pro­to­cols and media with­in one net­work, which can result in expen­sive and com­plex projects.  Avoid these prob­lems with inter­op­er­a­ble tech­nol­o­gy and smart con­fig­u­ra­tion tools.

MV Distribution Grid Automation

It is often dif­fi­cult to find the exact solu­tion you need in a MV appli­ca­tion, lead­ing to high­er costs than nec­es­sary. With our scal­able and adapt­able solu­tions you will be able to only pay for what you real­ly need, with­out com­prim­is­ing on qual­i­ty or security.

Photovoltaic Power Station

Using an open and scal­able SCADA sys­tem to mon­i­tor and con­trol a PV plant comes with many ben­e­fits on sev­er­al lev­els. Find out how advanced com­mu­ni­ca­tion tech­nol­o­gy affects PV oper­a­tion, main­te­nance, sys­tem design, invest­ment secu­ri­ty, profits…