Iec ts 62257 5 2015

3 Fig re B.6 – TN-C-S s stem 3-phase, 4-wire where the PEN con u tor is se arated into the protective con u tor PE an the neutral con u tor N elsewhere in the electrical in tal ation.. 3

IEC TS 62257- 5

Editio 2.0 2 15-12

elect rificat ion –

Part 5: Prot ect ion against elect rical haz rds

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IEC TS 62257- 5

Edit io 2.0 2 15-12

R ecommendat ions for renew able energy and hybrid syst ems for rural

elect rificat ion –

Part 5: Prot ect ion against elect rical haz rds

INT ERNAT IONAL

ELECT ROT ECHNICAL

FOREWORD 5

INTRODUCTION 7

1 Sco e 8

2 Normative ref eren es 8

3 Terms an def i ition 9

4 Clas ification of decentral sed rural electrif i ation s stems 1

5 Protection again t electric s oc 1

5.1 General 1

5.2 Req irements on the d.c side of a DRES 1

5.3 Req irements on the a.c side of a DRES 12 5.3.1 General 12 5.3.2 T s stem 12 5.3.3 TN s stem 12 6 Protection again t overc r ent 13 6.1 General 13 6.2 Protection again t overlo d c r ents 13 6.3 Protection again t s ort-circ its 13 7 Protection again t ris of f ire 13 8 Protection again t eff ects of l g tnin 14 8.1 Prin iple 14 8.2 Examples 14 8.3 Protection again t overvoltage 14 8.4 Protection again t direct l g tnin 14 9 Determination of the pic up are of a rod or wire (se IEC 6 3 5-3:2 10) 14 9.1 General 14 9.2 Op rational con ition an external influen es 14 9.3 Wirin s stem 15 9.4 Isolation an switc in 15 9.4.1 Isolation 15 9.4.2 Over c r ent protective devices 16 9.4.3 Resid al Cur ent Devices (RCD) 17 9.5 Surge protective devices 17 9.6 Earthin ar an ement, protective con u tors an protective b n in con u tors 18 9.6.1 Earth electrodes 18 9.6.2 Protective b n in con u tors 19 10 Verification 19 1 Op ration an maintenan e 19 An ex A (informative) Protection again t electric s oc in electrical in tal ation 2

A.1 Protection again t electric s oc 2

A.2 Automatic dis on ection of s p ly 2

A.2.1 General 2

A.2.2 In TN s stems 21

A.2.3 In TT s stems 21

A.4 Extra-low-voltage (SELV an PELV) 2

A.5 Electrical se aration 2

A.6 Ad itional protection 2

An ex B (informative) Typ s of LV distribution s stems e rthin 2

B.1 Terms an def i ition 2

B.2 Typ s of s stem e rthin u ed in DRES (Fig res are f rom IEC 6 3 4-1:2 0 ) 2

B.2.1 General 2

B.2.2 AC TN s stems 2

B.2.3 AC TT s stems 3

B.2.4 DC distribution s stems 3

An ex C (inf ormative) Clas if i ation of electrical eq ipment 41

C.1 Clas ification of resid al c r ent devices (RCDs) (se IEC 610 8, IEC 610 9, IEC 6 7 5, IEC 6 9 7-2, IEC 62 2 ) 41

C.2 Clas ification of circ it bre kers f or a.c o eration (se IEC 6 8 8-1, IEC 6 9 7-2) 4

C.3 Clas if i ation of s rge protective devices (se IEC 616 3-1 ) 4

An ex D (inf ormative) General inf ormation con ernin protection again t l g tnin 4

D.1 General 4

D.2 Protection again t l g tnin – Prin iples 4

Biblogra h 4

Fig re B.1 – General outl ne of the distribution s stem 2

Fig re B.2 – Distribution s stem of the smalest typ 2

Fig re B.3 – TN-S s stem 3-phase, 4-wire with se arate neutral con u tor an protective con u tor throu hout the distribution s stem 2

Fig re B.4 – TN-S s stem 3-phase, 3-wire with se arate e rthed lne con u tor an protective con u tor throu hout the distribution s stem 2

Fig re B.5 – TN-S s stem 3-phase, 3-wire with protective con u tor an no distributed neutral con u tor throu hout the distribution s stem 3

Fig re B.6 – TN-C-S s stem 3-phase, 4-wire where the PEN con u tor is se arated into the protective con u tor PE an the neutral con u tor N elsewhere in the electrical in tal ation 31

Fig re B.7 – TN-C-S s stem 3-phase, 4-wire where the PEN con u tor is se arated into the protective con u tor PE and the neutral con u tor N at the origin of the electrical in tal ation 3

Fig re B.8 – TN-C-S s stem – sin le-phase, 2-wire where the PEN con u tor is se arated into the protective con u tor PE an the neutral con u tor N at the origin of the electrical in tal ation 3

Fig re B.9 – TN-C s stem 3-phase, 4-wire with neutral an protective con u tor f un tion combined in a sin le con u tor throu hout the distribution s stem 3

Fig re B.10 – TN-S multiple source s stem 3-phase, 4-wire with se arate protective con u tor an neutral con u tor to c r ent u in eq ipment 3

Fig re B.1 – TT s stem 3-phase, 4-wire with e rthed protective con u tor an neutral con u tor throu hout the distribution s stem 3

Fig re B.12 – TT s stem 3-phase, 3-wire with e rthed protective con u tor an no distributed neutral con u tor throu hout the distribution s stem 3

Fig re B.13 – TN-S d.c s stem 3

Fig re B.14 – TN-C d.c s stem 3

Fig re B.16 – T d.c s stem 4

Fig re D.1 – Example of eff ects of a l g tnin stroke 4

Ta le 1 – Typology of decentral zed electrification s stems 1

Ta le 2 – Rated o eratin resid al c r ent of the protective device de en in on the

value of the e rthin resistan e 12

Ta le 3 – Numb r of protected p les with regard to the c aracteristic of the

distribution s stem 16

INTERNATIONAL ELECTROTECHNICAL COMMISSION

_

Part 5: Protection against electrical haz rds

1 Th Intern tio al Ele trote h ic l Commis io (IEC) is a worldwid org niz tio for sta d rdiz tio c mprisin

al n tio al ele trote h ic l c mmite s (IEC Natio al Commite s) Th o je t of IEC is to promote

intern tio al c -o eratio o al q e tio s c n ernin sta d rdiz tio in th ele tric l a d ele tro ic f i ld To

this e d a d in a ditio to oth r a tivitie , IEC p bls e Intern tio al Sta d rd , Te h ic l Sp cif i atio s,

Te h ic l Re orts, Pu lcly Av ia le Sp cif i atio s (P S) a d Guid s (h re fter refer e to a “IEC

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n-g v rnme tal org niz tio s laisin with th IEC als p rticip te in this pre aratio IEC c la orate clo ely

with th Intern tio al Org niz tio f or Sta d rdiz tio (ISO) in a c rd n e with c n itio s d termin d b

a re me t b twe n th two org niz tio s

2) Th f ormal d cisio s or a re me ts of IEC o te h ic l maters e pre s, a n arly a p s ible, a intern tio al

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tra s are tly to th ma imum e te t p s ible in th ir n tio al a d re io al p blc tio s An div rg n e

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th later

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Pu lc tio s

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in is e s ble for th c r e t a plc tio of this p blc tio

9) Ate tio is drawn to th p s ibi ty th t s me of th eleme ts of this IEC Pu lc tio ma b th s bje t of

p te t rig ts IEC s al n t b h ld re p n ible for id ntifyin a y or al s c p te t rig ts

The main tas of IEC tec nical commite s is to pre are International Stan ard In

ex e tional circ mstan es, a tec nical commit e may pro ose the publ cation of a tec nical

sp cification when

• the req ired s p ort can ot b o tained f or the publ cation of an International Stan ard,

despite re e ted ef forts, or

• the s bject is sti u der tec nical develo ment or where, for an other re son, there is the

f uture but no immediate p s ibi ty of an agre ment on an International Stan ard

Tec nical sp cif i ation are s bject to review within thre ye rs of publ cation to decide

whether they can b tran formed into International Stan ard

IEC 6 2 7-5, whic is a tec nical sp cif i ation, has b en pre ared by IEC tec nical

commit e 8 : Solar photovoltaic energ s stems

This second edition can els an re laces the first edition is ued in 2 0 It con titutes a

tec nical revision

The main tec nical c an es with regard to the previou edition are as fol ows:

– redefine the maximum AC voltage f rom 5 0 V to 1 0 0 V, the maximum DC voltage f rom

7 0 V to 1 5 0 V;

– removal of the lmitation of 10 kVA s stem size Hen e the removal of the word “smal ” in

the title an related ref eren es in this tec nical sp cification

This tec nical sp cification is to b u ed in conju ction with the IEC 6 2 7 series (sp cifical y

IEC TS 6 25 -1 to IEC TS 6 2 7-6)

The text of this tec nical sp cification is b sed on the fol owin doc ments:

En uiry draft Re ort o v tin

Ful information on the votin for the a proval of this tec nical sp cification can b fou d in

the re ort on votin in icated in the a ove ta le

This publ cation has b en draf ted in ac ordan e with the ISO/IEC Directives, Part 2

A l st of al p rts in the IEC 6 2 7 series, publs ed u der the general title Re omme datio s

for re ewa le e erg a d hybrid syst ems for rural electrific tion, can b fou d on the IEC

we site

Future stan ard in this series wi car y the new general title as cited a ove Titles of existin

stan ard in this series wi b updated at the time of the next edition

The commit e has decided that the contents of this publ cation wi remain u c an ed u ti

the sta i ty date in icated on the IEC we site u der "htp:/we store.iec.c " in the data

related to the sp cif i publ cation At this date, the publ cation wi b

• tran f ormed into an International stan ard,

• recon rmed,

• with rawn,

• re laced by a revised edition, or

• amen ed

A bi n ual version of this publcation may b is ued at a later date

IMPORTANT – The 'colour inside' logo on the cov r pa e of this publ c tion indic te

th t it contains colours whic are considere to be us f ul f or the cor e t

und rsta ding of its conte ts Us rs s ould theref ore print this doc me t using a

colour printer

The IEC 6 2 7 series inten s to provide to dif ferent players in olved in rural electrification

projects (s c as project implementers, project contractors, project s p rvisors, in tal ers,

etc.) doc ments f or the setin up of renewa le energ an h brid s stems with AC voltage

b low 1 0 0 V an DC voltage b low 1 5 0 V

These doc ments are recommen ation :

• to c o se the rig t s stem f or the rig t place;

• to desig the s stem;

• to o erate an maintain the s stem

These doc ments are foc sed only on rural electrif i ation, con entratin on, but not sp cific

to develo in cou tries They s ould not b con idered as al in lu ive to rural electrification

The doc ments try to promote the u e of renewa le energies in rural electrification; they do

not de l with cle n mec anisms develo ments at this time (CO

2emis ion, carb n credit, etc.)

Further develo ments in this f ield could b introd ced in future ste s

This con istent set of doc ments is b st con idered as a whole with diff erent p rts

cor esp n in to items for saf ety, s staina i ty of s stems aimin at the lowest lfe c cle cost

as p s ible One of the main o jectives is to provide the minimum s f ficient req irements,

relevant to the field of a plcation, that is: renewa le energ an hybrid of f-grid s stems

RECOMMENDA TIONS FOR RENEWA BLE ENERGY

Part 5: Protection against electrical haz rds

This p rt of IEC 6 2 7 sp cifies the general req irements for the protection of p rson an

eq ipment again t electrical hazard to b a pl ed in decentralsed rural electrif i ation

s stems Req irements de l n with protection again t electric s oc are b sed on b sic

rules f rom IEC 61 4 an IEC 6 3 4

Decentral zed Rural Electrification Sy tems (DRES) are desig ed to s p ly electric p wer f or

sites whic are not con ected to a large intercon ected s stem, or a national grid, in order to

me t b sic ne d

The majority of these sites are:

• isolated dwel n s,

• vi age hou es,

• commu ity services (publ c l g tin , pumpin , he lth centers, places of wors ip or c ltural

activities, administrative bui din s, etc.),

• economic activities (work ho s, micro-in u try, etc.)

The DRE s stems fal into thre categories:

• proces electrification s stems (f or example f or pumpin ),

• in ivid al electrif i ation s stems (IES) for sin le u ers,

• col ective electrification s stems (CES) for multiple u ers

Proces or in ivid al electrification s stems ex lu ively con ist of two s bs stems:

• an electric energ generation s bs stem,

• the u er's electrical in tal ation

Colective electrification s stems, however, con ist of thre s bs stems:

• an electric energ generation s bs stem,

• a distribution s bs stem, also cal ed microgrid,

• u er’s electrical in talation in lu in interf ace eq ipment b twe n the in talation an

the microgrid

The general req irements sp cif ied in this p rt of IEC 6 2 7 s ould b a pl ed to al the

identified categories of DRES Ap lcation to e c s bs stem of a DRES is de lt within a

sp cific s b art of IEC T 6 2 7-9

u dated referen es, the latest edition of the referen ed doc ment (in lu in an

amen ments) a pl es

IEC 6 3 4-4-41, L w-v ltag electric l inst allations – P art 4-41: P rote tion for safety –

Protect io a ainst electric sh c

IEC 6 3 4-4-4 , L w-v ltag electric l inst allations – P art 4-4 : P rote tion for safety –

Prot ect ion a ainst overc re t

IEC 6 3 4-4-4 :2 0 , L w-v lta e electric l inst all tio s – P art 4-4 : P rotection for safety –

Prot ect ion a ainst v lta e d isturb n es a d electroma n t ic d isturb n es

IEC 6 3 4-4-4 :2 0 /AMD1:2 15

IEC 6 3 4-5-5 :2 0 , L w-v lta e electric l inst all t io s – P art 5-52: Selection a d ere tion

of electric l e uipme t – Wirin syst ems

IEC 6 3 4-5-5 :2 01, Electric l installat io s of b ild ings – P art 5-53: Select ion a d ere tion

of electric l e uipme t – I solation, switc in a d c ntrol

IEC 6 3 4-5-5 :2 01/AMD1:2 0

IEC 6 3 4-5-5 :2 01/AMD2:2 15

IEC 6 3 4-5-5 , L w-volta e electric l inst allations – P art 5-54: Selection a d ere tion of

ele tric l e uipme t – Earthing ara g me ts a d protect ive c nd uctors

IEC 6 3 4-7-712, Electric l inst allations of b ild ings – P art 7-712: Re uireme ts for sp cial

installatio s or loc tions – Solar p ot ovolt aic (P V) p wer su ply systems

IEC 6 3 5-2:2 10, P rot ection a ainst lg t ning – P art 2: Risk ma a eme t

IEC 62 0 -3:2 10, Prote tio a ainst li htning – P art 3: P hysic l dama e to stru tures a d

life h z rd

IEC 61 4 :2 15, P rot ect io a ainst electric sh c – Commo asp cts for inst allation a d

e uipme t

IEC TS 6 2 7-1, Re omme dat ions for re ewa le e erg a d hybrid syst ems for rural

ele trific t ion – P art 1: Ge eral introduct io to IEC 6 25 series a d rural ele trific t ion

IEC TS 6 2 7-2, Re omme dations for re ewa le e erg a d hybrid syst ems for rural

ele trific tion – P art 2: From re uireme ts t o a ra g of electrific t io systems

IEC TS 6 2 7-3: Re omme dations for re ewa le e erg a d hybrid syst ems for rural

ele trific t ion – P art 3: P roje t d ev lopme t a d ma a eme t

IEC TS 6 2 7-4, Re omme dat ions for re ewa le e erg a d hybrid syst ems for rural

ele trific t ion – P art 4: System select io a d d esign

IEC TS 6 2 7-6, Re omme dations for re ewa le e erg a d h brid systems for rural

ele trific t io – P art 6: Ac e tan e, o erat io , maint en n e a d re la eme t

3 Terms and def initions

For the purp ses of this doc ment, the fol owin terms an definition a ply

device inten ed to l mit tran ient overvoltages an divert s rge c r ents; contain at le st one

non-lne r comp nent An a pl an e/device desig ed to protect electrical devices f rom voltage

spikes

3.6

prote tion a ain t ele tric s oc

provision of me s res red cin the ris of electric s oc

e ternal l g tning prote tion s stem

p rt of the LPS con istin of an air termination s stem, a down-con u tor s stem an an

e rth-termination s stem

3.13

e uipote tial bondin s stem

EBS

intercon ection of con u tive p rts providin eq ip tential b n in b twe n those p rts

Note 1 to e try: If a e uip te tial b n in s stem is e rth d, it f orms p rt of a e rthin ara g me t

4 Classif ication of decentral sed rural electrif ication systems

DRESs are clas ified into six dif ferent typ s Se Ta le 1

Table 1 – Typology of de e tral ze ele trific tion s stems

1

1.C

2

2.C

5

5.C

6

6.C

Notatio prin iple: Ti = in ivid al s stem, ty e i TjC = c le tiv s stem, ty e j

Stora e: stora e of e erg pro u e b o e of th g n rator of th s stem a d whic c n b re o v rte

Arc itecture an c aracteristic of the diff erent electrif i ation s stem typ s are develo ed in

The prin iples for the desig an erection of a d.c electrical circ it are simi ar to those for an

a.c circ it The main diff eren es con ern s ort-circ it c r ent calc lation an the selection of

the protective devices

Protection by extra-low voltage (SELV an PELV s stems) or protection by double or

reinforced in ulation s ould prefera ly b ado ted on the d.c side of DRES

Simple se aration, at le st, s ould b provided b twe n the a.c side an the d.c side u les

the in erter is not a le, by con tru tion, to fe d d.c fault c r ent into the a.c in talation

Earthin of one of the lve con u tors of the d.c side is p rmited, if there is at le st simple

se aration b twe n the d.c side an the a.c side

5.3 Re uireme ts on th a.c side of a DRES

Protection by u e of automatic dis on ection of s p ly s ould pref era ly b ado ted on the

a.c side of a DRES For e c circ it, maximum dis on ectin times given in IEC 6 3 4-4-41

s ould a ply

TN-S or TN-C-S s stem s ould prefera ly b u ed for decentral zed rural electrif i ation

s stem, TT s stem is ac e ta le IT s stem is normal y not u ed f or DRES an has hen e not

b en de lt with in this sp cification

A resid al c r ent protective device, with a rated resid al o eratin c r ent not ex e din

3 mA, s ould b provided as ad itional protection for e c in tal ation

Basic protection is provided by b sic in ulation of l ve p rts or by b r iers or en los res Fault

protection is provided by resid al c r ent devices regardin the resistan e value of the e rth

electrode to whic the PE con u tor is con ected The fault c r ent s ould b hig enou h to

activate the diff erential c r ent device The rated o eratin resid al c r ent I

w ith

≤

L

AL

Δn

=U

RU

This formula res lts in the values s own in Ta le 2

Table 2 – Rate operating re id al c r e t of the prote tiv de ic

Basic protection is provided by b sic in ulation of l ve p rts or by b r iers or en los res Fault

protection is provided by devices protectin again t over c r ents

Ad itional information is given in An exes A an B

6 Protection a ainst overcur ent

Protective devices s ould b provided to bre k an over c r ent flowin in the circ it

con u tors b fore s c a c r ent could cau e a dan er d e to thermal an mec anical ef fects

or a temp rature rise detrimental to in ulation, joints, termination (se IEC 6 3 4-4-4 )

6.2 Prote tion a ainst ov rloa c r e ts

The o eratin c aracteristic of a device protectin a ca le again t overlo d c r ent s ould

satisfy the two folowin con ition :

I is the contin ou c r ent-car yin ca acity of the ca le;

I is the rated c r ent of the protective device;

I is the c r ent en urin ef fective o eration in the con entional time of the protective

device

6.3 Prote tion a ainst s ort circ its

For ca les an isolated con u tors, e c s ort-circ it protective device s ould me t b th of

the fol owin con ition :

• The bre kin ca acity s ould not b les than the prosp ctive s ort-circ it c r ent at the

place of its in tal ation, ex e t where another protective device havin the neces ary

bre kin ca acity an co rdinated c aracteristic is in taled upstre m

• Al c r ent cau ed by a s ort-circ it oc ur in at an p int of the circ it s ould b

inter upted in a time not ex e din that whic brin s the con u tors to the admis ible lmit

temp rature For s ort-circ its of d ration up to 5 s, the time t , in whic a given s

ort-circ it c r ent wi raise the con u tors f rom the hig est admis ible temp rature in normal

d ty to the l mit temp rature can, as an a proximation, b calc lated f rom the formula:

ISk

where

t is the d ration in s;

S is the cros -sectional are , in s uare mi imetres;

I is the eff ective s ort-circ it c r ent, in amp res, expres ed as r.m.s value;

k is a factor takin ac ou t of the resistivity, temp rature co ff i ient an he t ca acity of

the con u tor material, an the a pro riate initial an final temp ratures

7 Protection a ainst risk of f ire

Where there is a ris of p rsonal injury or pro erty damage d e to fire cau ed by an e rth

f ault in the s stem, a resid al c r ent protective device s ould b provided at le st at the

origin of the u er’s in talation Its rated o eratin resid al c r ent s ould b ≤ 0 mA Su h

a device s ould switc al l ve con u tors

8 Protection a ainst ef fects of l ghtning

8.1 Prin iple

Inf ormation a out the eff ects of l g tnin on electrical s p ly s stems is given in An ex D

Decision f or lg tnin protective provision (lg tnin rod, s rge protective devices, etc.) s ould

b b sed on ris as es ment, takin ac ou t of the l g tnin f eq en y statistic , the

c aracteristic an p sition of the stru tures, the len th of the overhe d l nes, if an , the cost

an the requested avai a i ty of the eq ipment

8.2 Ex mple

Examples of ris as es ment method a pro riate for l g tnin protection can b fou d in

IEC 6 3 4-4-4 :2 0 , Clau e 4 3 an IEC 6 3 5-2:2 10, Provision f or lghtnin protection

of DRES

8.3 Prote tion a ainst ov rvolta e

Where protection again t overvoltage (f or example d e to in irect l g tnin ) is req ired, an

SPD(s) s ould b in tal ed b th at the distribution b ard of the micro-p wer plant, an at the

origin of the u er's in talation or as ociated with e c soc et-outlet

In talation of SPD s ould comply with IEC 6 3 4-5-5 :2 01, Clau e 5 4

To minimize voltages in u ed by l g tnin , the are of al wirin lo ps s ould b as smal as

p s ible

8.4 Prote tion a ainst dire t l ghtnin

Where protection again t direct l g tnin is req ired, the fol owin provision a ply:

• In case of win p wered generation, the l g tnin rod s ould b in tal ed at the s mmit of

the mast

• Where PV generation co xists with win -p wered generation, protection again t direct

lg tnin is general y ac ieved by placin the p nels in ide the pic -up zone of the win

-p wered generator mast

• Where PV generation is alone, the p nels can b protected by in tal n a protective wire

a ove the PV p nel or l g tnin rod/s with an a pro riate pic -up are

• Protection s ould b completed by the in tal ation of SPDs b twe n con u tors an

b twe n con u tors an e rth, with a pro riate c aracteristic (se IEC 6 3 4-5-5 :2 01,

Clau e 5 4)

9 Determination of the pick up area of a rod or wire (see IEC 62305-3:2010)

Al eq ipment s ould b selected ac ordin to the rules of IEC 6 3 4-5-5

9.2 Operational condition a d e ternal influe c s

Every item of eq ipment s ould b selected an erected in compl an e with the a pro riate

stan ard

Eq ipment s ould b s ita le f or the nominal voltage (r.m.s value for a.c.) of the circ it

con erned an for the overvoltages whic could oc ur

Eq ipment s ould b selected for the desig c r ent (r.m.s value f or a.c.) whic it has to

car y in normal service

Eq ipment on the d.c side s ould b s ita le f or direct voltage an direct c r ent

Eq ipment s ould also b ca a le of car yin the c r ents l kely to flow in a normal

con ition f or s c p riod of time as are determined by the c aracteristic of the protective

devices

If feq en y has an influen e on the c aracteristic of eq ipment, the rated f req en y of the

eq ipment s ould cor esp n to the f req en y an feq en y variation whic could oc ur in

the circ it con erned

The electrical eq ipment s ould with tan the exp cted external influen es s c as win , ice

f ormation, temp rature an solar radiation, etc If a piece of eq ipment do s not have, by

con tru tion, the neces ary q al ties cor esp n in to the location in whic it is in tal ed,

a pro riate ad itional protection s ould b provided, formin p rt of the in tal ation

Electrical eq ipment s ould b selected an erected so that it do s not prod ce, in normal

service, any interf eren e with the other eq ipment in the s stem The cau es of inter eren e

The minimum cros sectional are of con u tors s ould b determined ac ordin to:

• The c r ent-car yin ca acity of con u tors takin ac ou t of external influen es an of

the method of in tal ation Se ta les in IEC 6 3 4-5-5

• The ac e ta le voltage dro in con u tors of the u er’s in tal ation s ould b determined

ac ordin IEC 6 3 4-5-5 Voltage values s ould comply with the f ol owin l mits at the

terminals of an u er’s electrical eq ipment:

F r a.c voltage,

The purp se of isolation is to se arate a circ it or eq ipment u it f om the rest of the s stem

in order to g arante the saf ety of p rson who may have to work on, to maintain or re air it

Every circ it s ould b ca a le of b in isolated

In TN-C-S s stems, the PEN con u tor s ould not b inter upted (broken, switc ed or

dis on ected)

In TN-S s stems, the neutral con u tor ne d not b inter upted

Suita le me n (p dloc in , location within loc a le en los re, etc.) s ould b provided to

prevent an eq ipment f rom b in u intentional y energised

The isolatin distan e b twe n o en contacts s ould b visible or cle rly an rel a ly

Overc r ent protective devices s ould b prefera ly of a typ en urin protection again t b th

overlo d an s ort-circ it c r ents an ca a le of actin as isolatin switc in the o en

p sition

Sp cial at ention s ould b p id to over c r ent protective devices in tal ed in series, to

en ure that an a pro riate co rdination is ac ieved Selectivity b twe n protective devices in

series s ould prefera ly b total

9.4.2.2 AC ov r-c r e t protectiv de ic s

The n mb r of protected p les de en s on the neutral e rthin distribution s stem an on the

cros -sectional are the neutral con u tor, in ac ordan e with Ta le 3

NOT A prote te p le is a p le pro id d with a o erc re t rele s

Table 3 – Number of prote te p le with re ard to th c ara teristic

2: Th p wer c n ume b twe np a e a dn utral is <10 % of th total p wer tra smite b th main

3: Th ma imum c re t e p cte to f l w in th n utral c n u tor is le s th n its p rmis ible c re t

4: Th n utral c n u tor is prote te a ain t s ort-circ its b th ste s ta e to prote t th p a e c n u tors

9.4.2.3 DC ov r-c r e t prote tiv de ic s

For the selection of d.c overc r ent protective devices, it is recommen ed to b as isted by

the man facturer af ter havin determined an tran mited the c aracteristic of the circ it

(s ort-circ it c r ent, rated c r ent, time con tant

NOT For c lc latio of th s ort-circ it c re t in c s of a b tery wh s intern l re ista c is n t k own, th

f olowin formula c n b u e :

i

wh re R

i

is th intern l re ista c of th g n rator

For c lc latio of th s ort-circ it c r e t at a y p int of th in talatio , th f olowin f ormula c n b u e :

I

k

=1,1 × U

n/R

i+ 2R

N

of th

motor

9.4.3 Re idual Cur e t De ic s (RCD)

Resid al c r ent devices s ould b so selected, an the electric circ its so s bdivided that

an e rth le kage c r ent whic may b exp cted to oc ur d rin normal o eration of the

con ected lo d(s) wi b u l kely to cau e u neces ary trip in of the device

NOT Re id al c re t prote tiv d vic s c n o erate at a y v lu of e id al c re t in e c s of 5 % of th

rate o eratin c re t

Resid al c r ent protective devices in d.c s stems s ould b sp cial y desig ed f or detection

of d.c resid al c r ents, an to bre k circ it c r ents u der normal con ition an fault

con ition

For the s stems con erned, RCDs in tal ed upstre m s rge protective devices s ould b of

typ S, in order to alow service contin ity

9.5 Surge prote tiv d vic s

The selection an erection of SPDs s ould comply with IEC 6 3 4-5-5 :2 01, Clau e 5 4

The fol owin are the le din p rameters ne ded to select SPDs (se also Clau e C.3):

UP = protection level for nominal c r ent (f or example 2,5 kV, 1,5 kV)

UC = contin ou service voltage to b c osen on the b sis of main nominal voltage

I

omin l(8/2 wave) = nominal dis harge c r ent Stan ard values: 2 kA, 10 kA, 5 kA, etc

Use of SPDs in presen e of harmonic (e.g where non sine-wave in erters are u ed) is

pro lematic Due to harmonic , the agein of varistors is ac elerated One solution to

overcome this is to in tal SPDs in lu in internal sp rk-ga s in series with the varistor (SiC

or ZnO) New SPD tec nologies are to b con idered as wel

9.6 Earthing ar a geme t, prote tiv conductors a d prote tiv bondin con uctors

9.6.1 Earth ele trode

Materials an dimen ion of the e rth electrodes s ould b selected to with tan cor osion

an to have mec anical stren th

When selectin typ an emb d ed de th of e rth electrode, con ideration s ould b given to

local con ition so that soi dryin an f re zin wi b u lkely to in re se the e rth

resistan e of the e rth electrode to s c a value that would imp ir the protective me s res

again t electric s oc

9.6.1.2 Earth ele trode f or th s pply s stem

Examples of e rth electrodes whic may b u ed are:

• u dergrou d stru tural network emb d ed in f ou dation (fou dation e rth electrode),

Where p s ible, a f ou dation e rth electrode s ould b pref er ed

Common minimum sizes f or e rth electrodes of commonly u ed material can b fou d in

IEC 6 3 4-5-5

9.6.1.3 Earth termin tion (ele trode) of a l ghtning prote tion s stem

In order to disp rse the l g tnin c r ent into the e rth without cau in dan erou

overvoltages, the s a e an the dimen ion of the e rth termination s stem of an LPS are

more imp rtant than the value of the resistan e of the e rth electrode (c aracteristic

a pl ca le f or d.c or low f eq en y phenomena)

The e rth termination s stem s ould b comp sed of:

• either con u tors of the same nature an same cros -section as the down-con u tors (in

general, 3 mm × 2 mm co p r strip) laid out in the f orm of a large crow’s f oot:

3 con u tors 7 m to 8 m lon buried horizontal y at a de th of at le st 0,6 m,

• or a set of 3 vertical rod 2 m in len th con ected together an set out at the a exes of an

eq i ateral trian le with sides me s rin a out 2 m

The e rth termination s stem of the LPS s ould b b n ed to the e rthin ar an ement with

s ort con exion

9.6.1.4 Appl c tion to the prote tion of a ENR p wer s stem

The win -p wered generator an /or the fame of the PV p nels s ould be e rthed by a crow’s

f oot e rth electrode with the lowest p s ible resistan e (a 10 Ω at 5 Hz is f eq ently

ado ted) This e rth electrode s ould b b n ed, with s ort con exion , to the e rthin

ar an ement of the tec nical ro ms hou in the other eq ipment of the in talation

9.6.2 Prote tiv bon ing condu tors

Where protective eq ip tential b n in con u tors are in tal ed, they s ould b p ral el to

an in closest contact as p s ible with d.c ca les an a.c ca les an ac es ories

Annex A

(inf or mative)

Protection against electric shock in electrical instal ations

A 1 Protection against electric shock

The fu damental rule of protection again t electric s oc , ac ordin to IEC 61 4 , is that

hazardou -l ve-p rts s ould not b ac es ible an ac es ible con u tive p rts s ould not b

hazardou l ve either u der normal con ition or u der sin le f ault con ition

Ac ordin to IEC 61 4 , protection u der normal con ition is provided by b sic protective

provision an protection u der sin le fault con ition is provided by fault protective

provision Alternatively, protection again t electric s oc is provided by an en an ed

protective provision whic provides protection u der normal con ition an u der sin le f ault

con ition

Con eq ently, a protective me s re is:

• an a pro riate combination of a protective provision f or b sic protection and an

in e en ent protective provision f or fault protection, or

• an en an ed protective provision whic provides b th b sic protection an f ault protection

In e c p rt of an in tal ation, one or more protective me s res s ould b a pl ed Ex e t

otherwise sp cified, the fol owin protective meas res are p rmit ed:

• automatic dis on ection of s p ly;

• double or reinf orced in ulation;

• electrical se aration for the s p ly of one item of c r ent u in eq ipment;

• extra-low voltage

The fol owin protective me s res:

• u e of o stacles;

• placin out of re c ;

s ould only b u ed u der the control of s i ed or in tru ted p rson

The fol owin protective me s res:

• non-con u tin location;

• e rth-re local eq ip tential b n in ;

• electrical se aration for the s p ly of more than one item of c r ent u in eq ipment;

may b a pl ed only when the in tal ation is u der the control of s i ed or in tru ted p rson

so that u authorized c an es can ot b made

A 2 A utomatic disconne tion of supply

Automatic dis on ection of s p ly is a protective me s re in whic :

• b sic protection is provided by b sic in ulation of l ve p rts or by b r iers or en los res,

and

• f ault protection is provided by automatic dis on ection of s p ly

NOT 1 Wh re s e ifie , a ditio al prote tio is pro id d b a re id al c re t prote tiv d vic with rate

re id al o eratin c re t n t e c e in 3 mA

A protective device s ould automatical y dis on ect the s p ly to the circ it or eq ipment in

the event of a fault b twe n a l ve p rt an an exp sed-con u tive-p rt or a protective

con u tor in the circ it or eq ipment within the time req ired

The maximum dis on ection time is given in IEC 6 3 4-4-41

If automatic dis on ection can ot b ac ieved in the time req ired as a pro riate,

s p lementary protective eq ip tential b n in s ould b provided

In a.c s stems, ad itional protection by me n of a resid al c r ent protective device with

rated resid al o eratin c r ent not ex e din 3 mA s ould b provided for:

• soc et-outlets with a rated c r ent not ex e din 2 A, u der the s p rvision of ordinary

p rson , an

NOT 2 This a ditio al prote tio c n b in th s c et-o tlets (SRC ) or th circ it s p lyin th s c et-

o tlet

NOT 3 For e ample, d me tic dwel n s are n rmaly u d r th s p rvisio of ordin ry p rs n

• the final circ its for han -held an Clas I c r ent-u in eq ipment, with a c r ent ratin

not ex e din 3 A, for u e outdo rs where the eq ipment is con ected other than

throu h a soc et-outlet

is the imp dan e in ohms of the f ault lo p comprisin the source, the l ve con u tor up to

the p int of the f ault an the protective con u tor b twe n the p int of the fault an the

source;

I is the c r ent in amps cau in the automatic o eration of the dis on ectin device within

the time req ired When the protective device is a resid al c r ent protective device, this

c r ent is the rated resid al o eratin c r ent;

is the s m of the resistan e in ohms of the e rth electrode an the protective con u tor

f or the exp sed con u tive-parts;

I

∆n

is the rated resid al o eratin c r ent of the RCD

When an overc r ent protective device is u ed for fault protection, the fol owin con ition

is the imp dan e in ohms of the f ault lo p comprisin the source, the l ve con u tor up to

the p int of the fault, the protective con u tor of the exp sed con u tive p rts, the e rth

electrode of the in tal ation an the e rth electrode of the source;

I is the c r ent in amps cau in the automatic o eration of the dis on ectin device within

the time req ired;

U

o

is the nominal a.c r.m.s or rip le-f re d.c voltage, in volts to e rth

A 3 Double or reinf orce insulation

Double or reinforced in ulation is a protective me s re in whic :

• b sic protection is provided by b sic in ulation, an fault protection is provided by

s p lementary in ulation, or

• b sic an fault protection is provided by reinf orced in ulation b twe n l ve p rts an

ac es ible p rts

NOT This prote tiv me s re is inte d d to pre e t th a p ara c of d n ero s v lta e o th a c s ible p rts

of ele tric le uipme t thro g a fa lt in th b sic in ulatio

A 4 Extra-low-voltage (SELV a d PELV)

Protection by extra-low-voltage is a protective me s re whic con ists of two diff erent

extra-low-voltage s stems:

• protective se aration of the SELV or PELV s stem f rom al circ its other than SELV an

PELV circ its, an b sic in ulation b twe n the SELV or PELV s stem an other SELV or

• f ault protection is provided by simple se aration of the se arated circ it f om other circ its.

This protective me s re s ould b l mited to the s p ly of one item of c r ent u in

eq ipment s p l ed f om one u e rthed source with simple se aration

A 6 A dditional protection

The u e of resid al c r ent protective devices, with a rated o eratin resid al c r ent not

ex e din 3 mA, is recog ized in a.c s stems as ad itional protection in the event of fai ure

of other b sic protective provision or careles nes by u ers