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Relay protection library for designers: protection relays, functions, standards

Relay protection and automation (RZA) detects short circuits, earth faults, undervoltage or underfrequency and disconnects the faulty part of the network. This page is a reference for designers of 6–10 kV KSO cubicles, distribution points and packaged substations: which protection relays LK Energy installs, which protection functions they provide, where the manufacturers’ official documentation is, and which of our standard schemes use them.

Our experience is counted from our own specification database for 2016–2026, not from catalogues. The table lists only relays present in our 2023–2026 specifications, with functions for the versions we used; older ones are listed in one line below it. Manufacturer documents are not re-published — links go to the manufacturers’ official websites.

Updated: 23.09.2026 · Author: engineering department, LK Energy

20 · relays in the table

Protection relays LK installs

Model and manufacturer, our experience from the specification database, protection functions per the manufacturer’s documentation, official documentation links and our standard schemes with this relay. Sorted by frequency.

RelayLK experienceProtection functionsManufacturer documentationOur standard schemes
MRZS-05Mdiscontinued (manufacturer’s 2026 catalogue); in our specifications: versions -13.2, -18, -19Kyivprylad / Promavtomatyka327 specification lines2016–2024-13.2 — feeder5167N2759467950BFBBL-19 — VT: voltage protection275959Nno manufacturer documentation for version -18; MRZS-U replaces -19Scheme catalogue (DWG):ЛК-ТР-10-RP-008ЛК-ТР-10-RP-009
MRZS-F2 / S2 / U2 / T2new MRZS generation; in our specifications: F2A12, F2D12, F2D14, F2G12, F2H32, F2I14, F2J12, F2J14, F2L12, S2G12, S2H32, S2J12, S2J14, U2B12, U2D12, U2J14, T2G12Kyivprylad / Promavtomatyka172 specification lines2019–2026F2 — feeder, incomer516750N/51N67N59N275946ARC50BFBBL7981UFRCT tripS2 — bus section5167275946ARC50BFBBL79ATS25CT tripU2 — VT: voltage protection275959N4681UFRARCT2 — transformer87T516750N/51N67N59N27594663/2650BFper the manufacturer’s 2026 catalogue: arc protection started via a binary input or by fibre-optic sensors (optical inputs in some configurations); de-shunting only with “3” in the 4th code position (ours: F2H32, S2H32), instead of optical inputs; T2: gas and thermal trips from relay contacts via binary inputsScheme catalogue (DWG):ЛК-ТР-10-RP-008
MRZS-05Lin our specifications, among others: versions -12, -12.1, _m -40.1 and -20 (central alarm)Kyivprylad / Promavtomatyka163 specification lines2016–2026-12, -12.1 — incomer, bus section, feeder516750N/51N67N59N275946ARC50BFBBL7981UFRATS_m -40.1 — incomer, feeder5150N/51N67N59N46EXT50BFBBL7981UFRCT trip-20 — central alarmCAper the 2026 MRZS-05L catalogue: ATS only in -12; in _m -40.1 AFLS via binary input, de-shunting in -40.1 and -50.1Scheme catalogue (DWG):ЛК-ТР-10-RP-016
RS83-AV2RZA Systems160 specification lines2019–2026516767N4627597981UFRBBL50BFATSARC63/26CT tripATS: start from undervoltage/overvoltage, the ATS cycle by an external circuit; AFLS/reclose on a signal from an external frequency relay (binary input); negative-sequence and overvoltage are alternative versionsScheme catalogue (DWG):ЛК-ТР-10-RP-012ЛК-ТР-10-RP-016ЛК-ТР-10-RP-017ЛК-ТР-10-RP-020ЛК-ТР-10-KRUN-003
RS80-MRin our specifications: RS80-MR-1221, -1222, -12310, -12320 (two-phase with 3I0), -32210, -32310, -3232, -3241 (three-phase)RZA Systems131 specification lines2016–2025515067NBBL7981UFREXTCT tripdirectional earth fault (67N) only in two-phase versions; de-shunting per order code (third digit “1” or “3”)Scheme catalogue (DWG):ЛК-ТР-10-KTP-010
RS83-A2.0RZA Systems64 specification lines2016–20255150N/51N467981UFRBBL50BFARC63/26CT tripde-shunting per order code (4th position “1”); present in some of our versionsnot in the open solutions of this section
RS83-A2Min our specifications: RS83-A2M onlyRZA Systems57 specification lines2018–20265167N467981UFRBBL50BFARC63/26CT tripde-shunting per order code (4th position “1”); present in some of our versionsScheme catalogue (DWG):ЛК-ТР-10-RP-017
RS80-M2two-phase overcurrent relays; in our specifications: RS80-M2-4, -8, -28 and RS80-M2M-8RZA Systems34 specification lines2017–2025515050N/51Nearth fault only in RS80-M2-28; breaker failure and de-shunting exist in other versions, not in oursnot in the open solutions of this section
Easergy P3U30Schneider Electric18 specification lines2020–202651506750N/51N67N59N2759464948/6650BF7981U81O/81Rrange renamed PowerLogic P3; P3U30 is a P3 Standard relay without arc-flash sensor inputs; motor protection only in motor modenot in the open solutions of this section
RS83-AV3RZA Systems17 specification lines2022–2026516750N/51N67N59N4627597981UFRBBL50BFATSARCAFLS/reclose via binary input or by its own frequency measurement
RS40in our specifications: RS40-M1 (single-phase, definite time delay) and RS40-M2 (two-phase, no time delay)RZA Systems15 specification lines2017–20245150not in the open solutions of this section
RS83-V1RZA Systems15 specification lines2019–2026275959N46Scheme catalogue (DWG):ЛК-ТР-10-KRUN-003
RS83-SRZA Systems8 specification lines2019–2026CAnot a feeder relay: alarm/warning signalling and telemechanicsnot in the open solutions of this section
VT Guard ProVT ferroresonance protection deviceABB7 specification lines2021–2024VT FRnot in the open solutions of this section
Sepam series 40Schneider Electric6 specification lines2017–2026516750N/51N67N59N2759464948/667981U81H50BFBBL63/26depends on type: S substation, T transformer, M motor, G generatornot in the open solutions of this section
REF611 / REF615 / REX615ABB5 specification lines2021–2025REF61151506750N/51N67N59N464950BF79REF61551506750N/51N67N59N2759464950BF7981U81O/81RARCREX615515050N/51N59N2759464950BF7981U81O/81RARCREF611/REF615: standard configurations; REX615: application packages (ours: APP1, APP3, APP5); functions depend on themScheme catalogue (DWG):ЛК-ТР-10-RP-018
Altra 32-z-16IMSKOE4 specification lines2018–202650N/51NDRearth-fault protection and a 16-channel recorder
Easergy P3F30Schneider Electric3 specification lines2022–202451506750N/51N67N59N2759464950BF7981U81O/81RARCrange renamed PowerLogic P3; arc protection with optional arc sensorsnot in the open solutions of this section
RZL-01versions RZL-01.01, RZL-01.02RELSiS2 specification lines2024–2026515050N/51N7950BFBBLde-shunting only in version .03, not in our .01 and .02not in the open solutions of this section
RS83-A3 / RS83-VS3RZA Systems2 specification lines2026RS83-A35167N50N/51N59N467981UFRBBL50BFATSARCRS83-VS35167502167N50N/51N59N4627597981UFR2550BFRS83-A3: AFLS/reclose via binary input; RS83-VS3 has no built-in arc protection (user logic only)not in the open solutions of this section

“LK experience” is how many times a relay of this family appears in LK product specifications (1C database, 2016–2026) and in which years. It is neither the number of orders nor the number of devices: one specification may cover several identical cubicles. Functions follow the manufacturer’s documentation; which of them are used on a given feeder is defined by the project.

Abbreviations
51
time-delayed overcurrent, ANSI 51
50
instantaneous overcurrent, ANSI 50
67
directional overcurrent, ANSI 67
21
distance protection, ANSI 21
50N/51N
earth-fault protection, ANSI 50N/51N
67N
directional earth fault, ANSI 67N
59N
neutral voltage displacement, ANSI 59N
27
undervoltage, ANSI 27
59
overvoltage, ANSI 59
46
negative sequence / broken conductor, ANSI 46/47
49
thermal overload, ANSI 49
48/66
motor protection: long start, locked rotor, starts per hour, ANSI 48/51LR/66
87T
transformer differential, ANSI 87T
ARC
arc-flash protection with optical sensors
BBL
busbar blocking (logic discrimination)
50BF
breaker failure, ANSI 50BF
79
auto-reclose, ANSI 79
81U
under-frequency load shedding, ANSI 81U
FR
reclosing after frequency recovery
81O/81R
overfrequency and rate of change of frequency, ANSI 81O/81R
25
synchro-check, ANSI 25
ATS
automatic transfer of supply
63/26
Buchholz and temperature trips of the transformer (binary inputs), ANSI 63/26
t°
transformer temperature signals: alarm and protection
CT trip
CT-powered tripping (de-shunting) for AC auxiliary supply
CA
substation central alarm
DR
disturbance recorder
VT FR
VT ferroresonance protection
L/S/I
0.4 kV breaker trip unit: overload and short-circuit settings
EXT
external protection: trips from external sensor contacts via binary inputs
81H
overfrequency, ANSI 81H/81O

Installed earlier but absent from our 2023–2026 specifications, so not in the table: MRZS-05, Sepam 20, UZA-10, RS80-M3, RZL-05, ZZN2-4, RS830-M2, VAMP.

Protection by object

Protection functions by object — as in our schemes

Which protections are used on each feeder and on which relay — only what is on the sheets of our standard solutions. The set for your project is defined by the design and the distribution system operator’s requirements.

6–10 kV RP/KSO switchgear and 10 kV KRUN

Cubicles with vacuum breakers and numerical relays; busbar blocking and arc protection link the cubicles via dedicated signal buses.

Feeder / bayProtection functionsRelay / deviceStandard solutions
Incomerundervoltage feeds the ATS; arc protection in the KM-1F version; in KRUN a separate CT core goes to differential protection circuits5150BBL50BF27ATSARCRS83-AV2 (KSO), RS83-AV3 (KRUN), MRZS-F2J12 (KM-1F)
Bus-section breakerbusbar blocking: a feeder pick-up blocks the incomer and section overcurrent5150BBLATSARCRS83-AV2; ATS by RS80-MAVR (RP 10 kV) or RS80-AVRM (retrofit); RS83-AV3 (KRUN); MRZS-S2J12 (KM-1F)
Outgoing feederearth fault from a core-balance CT (TZLU); auto-reclose and AFLS in KRUN515050N/51NBBL50BF7981UFRARCRS83-AV2, RS83-AV3 (KRUN), MRZS-F2J12 (KM-1F)
Voltage transformer (VT)voltage check for the ATS, 3U0 — earth-fault signal59N27RS83-V1 (KRUN, retrofit), MRZS-U2D12 (KM-1F); Altra 32-z-16 in the retrofit
Auxiliary transformerATSauxiliary transformer secondary protection, auxiliary supply ATS
Bus-section disconnector and central alarmCAARCMRZS-05L (central alarm) — KM-1F

10(6)/0.4 kV substations (TP, KTP)

The transformer is protected on the 6(10) kV side by a relay in the switchgear cubicle; on 0.4 kV by the incoming breaker releases (see below).

Feeder / bayProtection functionsRelay / deviceStandard solutions
6 kV transformer protection cubicle (KTP for a solar plant)the transformer protection set is not detailed in the questionnaire—RS83-AV2 (the diagram shows “protection” and “de-shunting”)
10 kV feeder to the transformer (KTP-1000 for a solar plant)transformer temperature wired to the relay: t > 90 °C alarm, t > 125 °C protection signalt°RS80-MR

0.4 kV incomers: LV boards (RUNN, ShchO-90)

On 0.4 kV protection is provided by the circuit-breaker trip units; settings are given in the questionnaire.

Feeder / bayProtection functionsRelay / deviceStandard solutions
0.4 kV circuit breakers (incomers, feeders)L/S/Ibreaker trip units; setting ranges are in each solution’s questionnaire (e.g. ShchO-90 for a substation: long-time (0.4…1)×Ir, instantaneous (4…14)×Ir)
Bus-section breaker with ATSATSelectronic ATS controller, incomer voltage relays (ShchO-90-1313 panel)

Diesel generator and ATS 0.4 kV

Feeder / bayProtection functionsRelay / deviceStandard solutions
ATS mains — generator and for two mains incomersATSthree-phase voltage monitoring relay on each incomer, electrical interlock against simultaneous closing, priority incomer selection

Under-frequency load shedding 35/10 kV

Feeder / bayProtection functionsRelay / deviceStandard solutions
AFLS cabinet and control-room panelauto-reclose blocking, outputs to central alarm and recorder81UFRCAAFLS device RZM-A.ACHR; separate AFLS and reclose switches for 35 and 10 kV
6 · standards

Standards for relay protection design in Ukraine

Documents our schemes rely on. Status checked against official sources on the date shown in each row.

DocumentWhat is in it for relay protectionStatus
PUE:2026Electrical Installation Rules of Ukraine, PUE (Ministry of Energy order No. 283 of 05.06.2026)sies.gov.ua — list of orders in force ↗Section 3 “Protection and automation”: chapter 3.2 relay protection, 3.3 automation and telemechanics, 3.4 secondary circuits; chapter 4.2 — switchgear and substations above 1 kV.in force; replaced PUE:2017 (order No. 476)checked 23.09.2026
PTEESRules for technical operation of consumer electrical installations (order No. 258 of 25.07.2006)Section VII, chapter 6 “Relay protection, automation and secondary circuits”; clause 6.7 — settings of consumer feeders supplied from the operator’s network are agreed with the operator.in force, rev. 21.02.2017 — per the document text as of 09.09.2026
Distribution System CodeDistribution System Code, NEURC resolution No. 310 of 14.03.2018nerc.gov.ua ↗Operation of and connection to distribution networks; protection devices are listed among dispatch-controlled equipment and emergency control means.in force, rev. 01.09.2026checked 23.09.2026
DSTU EN 60255-151:2018Measuring relays and protection equipment — Part 151: functional requirements for over/under current protection (IEC 60255-151:2009)Requirements for over- and under-current protection functions of relays.in force (standards catalogue, 09.09.2026)
DSTU EN IEC 62271-200:2022AC metal-enclosed switchgear above 1 kV up to and including 52 kV (IEC 62271-200:2021)Standard for 1–52 kV metal-enclosed switchgear hosting the protection relays.2022 edition; DSTU EN 62271-200:2015 cancelled from 01.07.2024
GKD 341.004.001-94Design standards for AC substations with the highest voltage of 6–750 kV (sectoral guidance document)Substation design standards; section 2 (electrical schematic diagrams) was replaced by SOU-N EE 20.178:2008.in force except section 2 (catalogue, 09.09.2026)

DSTU and GKD are listed without links: DSTU standards are distributed by the national standards body (paid); GKD 341.004.001-94 is a sectoral guidance document of the power industry.

Settings

Settings: what the manufacturer gives and what the project does

Settings of overcurrent, instantaneous overcurrent, earth-fault protection, under-frequency load shedding and time delays are calculated by the designer from the network short-circuit currents, the Ukrainian Electrical Installation Rules (PUE, chapter 3.2) and the distribution system operator’s requirements. For consumer feeders supplied from the operator’s network the settings are agreed with the operator (PTEES, clause 6.7). The relay only executes the settings.

Manufacturers rarely publish setting-calculation methods; setting forms and test procedures are more common — look for them in the technical libraries on the manufacturers’ websites linked above.

What is not on this page — and why

  • Manufacturer document files: only links to official websites, where editions are kept up to date.
  • Third-party standard design albums and textbooks: they are not ours to publish.
  • Drawings of specific orders: only standard solutions cleaned of customer data.
Questions and answers

FAQ

What is RZA?
RZA stands for relay protection and automation: devices that detect short circuits, earth faults, undervoltage or underfrequency and disconnect the faulty part of the network or switch in a standby supply. In 6–10 kV KSO cubicles these functions are performed by a numerical protection relay; in our 2016–2026 specifications the most frequent are MRZS-05M, the new MRZS generation, MRZS-05L and RS83-AV2.
How to choose a protection relay for a KSO cubicle?
By the cubicle role (incomer, bus section, feeder, VT, auxiliary transformer), the functions required by the project (overcurrent, instantaneous overcurrent, earth fault, under-frequency load shedding, auto-reclose, busbar blocking, breaker failure), the type of auxiliary supply and the distribution system operator’s requirements. The table above shows the functions of every relay we install and our standard schemes with it; the final choice is made by the project.
Do you publish relay documentation?
No. We do not re-publish manufacturer documents — we link to their official websites, where the current editions are. Our own material is the standard solution schemes: PDF open, DWG after a short registration.
Can I get the protection scheme of a cubicle in DWG?
Yes. PDF schemes of the standard solutions are open without registration; the DWG set is available after a short registration (name, phone, e-mail). For your project, send a single-line diagram or brief — we will select a standard solution and provide a questionnaire and a specification.

Need DWG files or a specification for your project?

Register — DWG sets of standard solutions and of the scheme catalogue are available after a short registration (name, phone, e-mail). For a specification for your project, send a single-line diagram or brief in the form.

Register and get DWG →

+380 67 104 94 91
Viberinfo@lk-energy.com.ua
Specification for your project

Send your single-line diagram or specification to info@lk-energy.com.ua — or we will contact you and ask.

See also

Typical solutionsRP and KSORPADiagrams