AREVA MBCH 12 13 Differential Protection

Type M BCH 1 2 , 1 3 , 1 6 Biased Differential Protection for Transformers, Generators and Genera tor Tra Tra ns nsform form ers

Type M BCH 1 2 , 1 3 , 1 6 Biased Differential Protection for Transformers, Genera tors a nd Genera tor Tra nsformers

Figure 1: R elay Type MBC H 16 withdrawn from case

Features • Independent single p hase relays suitable for single or three phase transformer p rotection schemes • Fast op erating times, typica lly 1 0 m s to 2 5 m s • Dual slope percentage bias restraint cha racteristic w ith ad justab le ba sic threshold setting o f 1 0 % to 5 0 % I n , selectable i n 1 0 % ste p s • Hig h stab ility d uring through faults even under conditions of CT sa t ur a ti o n a n d w i th u p t o 2 0 % ratio imbalance resulting from the effects of tap chang ing a nd C T errors • M ag netising in rush restraint overexcitation (over-fluxing) restraint • Up to six b iased inputs • Transformer p hase group and line CT ratio co rrection b y mea ns of sepa rate tap ped interposing transformers where required • Tw o isolated chang e-over tripping contacts plus one isolated normally open latching alarm contact. The individua l pha se elements can b e interconnected to provide six isolated cha ngeover tripping contacts for three phase schemes

Application The type MBCH 12, 13 and 16 are high- speed, single p hase, biased differential relays suitable for the protection of two- o r three-winding power transformers, autotransform ers, or generatortransformer units. Up to six biased current inputs can be p rovided to cater for pow er transform ers with m ore than two windings and/ or m ore than on e circuit-breaker

controlling each winding , as in ‘m esh’ o r ‘one a nd a half circuitbreaker’ busbar arran gem ents. Typical applications are shown in Figures 2 to 8 . As a general low impedance biased differential relay, the MBCH m ay also be regard ed as an a lternative to the high im pedan ce type relay for the protection o f reactors, m otors and g enerators.

M odels Ava ila ble Ty p e D esi g na ti o n N o . o f Bi a s A p p l ic a ti o n Circuits M BC H 1 2

2

Tw o -w ind ing p o w er tra nsfo rm er

M BC H 1 3

3

G enera lly 3 w ind ing p o w er tra nsfo rm er, w here bia s is required from ea ch of the 3 gro ups of C Ts

M BC H 1 6

6

Fo r a ll a p p lica tio ns req uiring 4 , 5 o r 6 bias circuits

• Light emitting diode (led) fault indication.

2

Description The relay is extremely stab le durin g through faults and provid es highspeed operation on internal faults, even when energ ised via line current tran sformers of o nly mo dera te output. Immunity to false tripping due to large inrush currents on energisation of the po w er transformer, and also during overfluxing cond itions, is provided by the use of a novel feature not involving harmonic filter circuits and their associated delay. It can be beneficial to supplement the differential protection by a restricted earth fault relay, especially w here the neutral p oint of the power transformer is earthed via a current limiting resistor. The restricted ear th fault relay (typ e M C A G 1 4 o r M FA C 1 4 ) ma y b e connected into the differential circuitry, in association with a current tran sformer i n the neutral connection of the po w er transformer, as indicated in Figures 3 a n d 6 . A d d i t io n a l l i n e c u rr e nt transformers are not required. For o ptimum performa nce, the differential scheme should be arrang ed so that the relay w ill see rated current w hen full loa d current flow s in the p rotected circuit. This may be achieved either by a p p r o p r i a t e c h o i ce o f m a i n l i n e current transformers, or the use of interposing current transformers. W h e n p ro te c ti n g a p o w e r transformer, the differential setting should no t be less than 2 0 % relay rated current, to gi ve stability for moderate transient overfluxing. The max imum spill current w ith through load current should g enerally be kept below 2 0 % of the relay ra ted current, allowing for CT mismatch and possible tap changer op eration. W here higher levels of spill current exist, the relay setting may need to b e increased. A tap ped interposing transformer is ava ilable for ratio matching of the ma in current tran sformers. The tap s are spaced a t intervals of 4 % and better, allow ing m atching to w ell w ithin 2 % in m ost cases. The same interposing transformers may also

be used w here necessary for p ow er transformer ph ase shift correction. For some a pp lications, no p hase shift correction is necessary, but a zero sequence current trap is required to prevent zero sequence currents, d ue to ex ternal ea rth faults being seen by the differential relay. Tw o s e co n d a r y w i n d i n g s a r e provid ed o n the interposing transformer to a llow the creation o f an isolated delta connection for this purpose. Each relay case incorporates a terminal b lock, for external connections, into w hich the module is plugged . Removal o f the mod ule from the case automatically causes the incoming line current transformer conn ections to be short-circuited, follow ed b y the open circuiting o f the relay tripping circuit. Setting a djustment is by mea ns of frontplate mounted switches. Indication of relay o peration is p r o v i d e d b y a n l e d , a l so m o u n te d on the relay frontplate, and w hich is resettab le by a push button o perab le with the relay cover in position. The output elements consist of aux iliar y attracted arm ature relays, the contacts of w hich are cap ab le of circuit-brea ker trip pin g. Three electrically independent contacts, comprising two self-resetting changeover contacts and one hand reset, normally open contact are provided per p ole, for circuit breaker tripping and alarm purposes respectively. By interconnecting relays as shown in Figure 9, up to six self-resetting change-over contacts can be provided for the three-phase tripping of up to six circuit-brea kers.

Functional Description The d ifferentia l transform er protection measuring circuit is based on the w ell know n M erz-Price circulating current principle. Figure 1 0 show s the relay functiona l block d iag ram. The outputs from ea ch b ias restraint tran sformer T3 to T5, proportional to the appropriate primary line currents, are rectified a n d su m m e d to p r o d u c e a b i a s restraint voltag e. A ny resulting di fference current is circulated through transformers T1 and T2. 3

The o utput from T1 is rectified an d comb ined w ith the bias voltag e to p r o d u c e a si g n a l w h i c h i s a p p l i ed to the amplitude comparator. The comp ara tor output is in the form o f pulses w hich vary in w idth dep ending on the amplitude of the combined bias and difference voltag es. W here the measurement of the interval betw een these pulses ind ica tes less tha n a preset time, a n internal fault is indica ted and a trip signal, initiated after a short delay ( 1 s), level set by the b ia s. If, d uring f the ab ove mentioned d elay, the instantaneous value of differential current falls below the threshold and remains below for long er than a 1 further pre set time, ( 4 f s) a s it w ou ld during transformer mag netising inrush cond itions, the trip timer is reset and op eration of the relay blocked. A n unrestrain ed hig h-set circuit, which monitors the differential current, w ill override the am plitude comp ara tor circuit and op erate the relay output element when the difference current is above the highset setting. Variable percentage b ias restraint Even under norma l opera ting conditions, unbala nced currents (spill current), ma y a pp ear. The magnitude of the spill current depends largely on the effect of tap chang ing. During through faults the level of spill current w ill rise a s a function of the fault current level. In o r d e r to a v o i d u n w a n t ed o p e r a ti o n due to spill current and yet maintain hig h sensitivity for internal fa ults, w hen the difference current may b e relatively small, the variable percentag e b ias restraint characteristic shown in Figure 11 is used. The setting I s is defined as the minimum current, fed into one of the bias inputs and the differential circuit, to ca use op eration. This is adjustable between 10% and 50% of ra ted current. The initial bia s slope is 20 % from zero to rated current. This ensures sensitivity to faults w hilst allow ing a 15% current transformer ratio mismatch when the power

transformer is at the limit of its tap rang e, plus 5% for CT ratio error. A bo ve rated current, extra errors m a y b e g r a d u a l l y i n tr o d u c e d a s a result of CT saturation. The b ia s slope is therefore, increased to 8 0 % to com pen sate for this. A t the inception of a through fault the bias is increased to more than 100%. It then falls exponentially to the steady state cha racteristic show n in Figure 11. This transient bias ma tches the transient differential currents that result from CT saturation d uring through fa ults, so ensuring stabi lity. However, during internal faults this transient bias is suppressed to ensure that no a dd itiona l delay in op eration is caused. The transient bias circuits of the three pha ses are externally interconnected to ensure optimum stability of the protection during through faults.

restraint a new technique ha s been developed to recog nise mag netising inrush current and restrain the relay during such period s. In practice the magnetising inrush current waveform is characterised b y a p e r i o d d u r i n g e a c h c y c le w h e n little or no current flow s, as show n in Figure 1 2 . By measuring this characteristic zero p eriod, the relay is able to determine whether the di fference current is due to ma gn etising inrush current or to genuine fault current and thereby inhibit opera tion o nly during the inrush cond ition. This new mea surement technique ensures that operating times remain unaffected even during p eriods of significant line C T saturation. Tra nsform er over-ex citation

Since the inrush current flow s only in the energised w inding the pro tection relay sees this current as difference current. To avoid unw anted tripping of the power transformer it has been customa ry to incorpo rate second harmonic restraint to block the protection relay. Practice has shown that this technique ma y result in significantly slow er op erating times for internal faults when second harmo nics are introduced into the current w aveform b y co re saturation of li ne C Ts.

W hen a large section o f system load is sudd enly disconnected from a p ow er transformer the voltag e at the inp ut termina ls of the transformer m a y r i se b y 1 0 -2 0 % o f r a t ed v a l u e giving rise to an appreciable increa se in transform er stead y state exciting current. The resulting exciting current may rise to a value high eno ugh to op erate the di fferential p rotection relay, since this current is seen by the input line current transformers only. Exciting currents of this order a re d ue to the input voltag e exceeding the knee point voltage of the power transformer resulting in a mag netising current w ave shape a s show n in Figure 13 . By detecting the periods w hen the current remains close to or at zero, in a similar ma nner to that used to identify magnetising inrush current, the relay is able to detect and rema in i nsensitive to substan tial over-excitation current.

In ord er to o vercome the prob lems associa ted w ith second ha rmonic

W h e r e e x tr e m el y l a r g e a n d po tentially d ama ging over-exciting

M ag netising inrush restraint Par ticularly hig h inrush currents may occur on transformer energisation d e p e n d i n g o n th e p o i n t o n w a v e o f switching as well as on the ma gn etic state of the transformer core.

4

currents are po ssib le it is recommended that an over-fluxing relay, respo nsive to V/ Hz , should be used. Such relays are designed to o perate after a time delay of several seconds High-set An unrestrained instantaneous highset feature is incorp ora ted to provid e extremely fast clearance o f hea vy in ternal faults. This instantaneous feature has an autoranging setting, normally low at norma l load through-put, but automatically rising to a higher value under heavy through fault conditions. Furthermore, immunity to ma gn etising current inrush is gua ranteed provid ed the first peak of the wa veform is no g reater than 1 2 times the rated rms current. The prob lem relating to choice of a high-set threshold which avoids tripp ing o n mag netising current inrush does not, therefore, o ccur and no user adjustment is required. Auxiliary interposing transformer A uxiliary interposing transformers are a vailab le as single o r triple unit assemblies as illustrated in Figure 15. A comp rehensive tap ad justment range is available as indicated by the details of turns per tap shown in Tab le 2. A ll line C T conne ctions should be made to the terminal strip m a r k e d ‘ S 1 S 2 S 3 S 4 P1 P2 ’ . Selection of appropriate primary taps is made using the flexible  jum p er le a d s co nnecte d to te rm ina ls P1 and P2 . See Figure 1 6 . The tertiary w inding S3-S4 m ust be used in series with winding S1-S2 w h e r e a d e l ta o u tp u t w i n d i n g i s required to ensure correct operation of the di fferential scheme.

DY1

A

A

B

B

C

C

23 25 27 MBCH 12 24 26 28

12

23 25 27 MBCH 12 24 26 28

12

23

25

27 12 MBCH 12

24

26

28

Figure 2: Application diagram: relay type MBC H 12 with two b iased inputs

DY1 A B C

Restricted E/ F relay

Phase 'A' Relay

Phase 'B' Relay

23

27

25

12

MBCH 12 24

26

28

23

25

27 12

MBCH 12 24

23

26

25

28

27

Phase 'C' Relay

12 24

26

28

MBCH 12

Figure 3: Typical connection diagram for MBC H 12 relays protecting a DY 1 transform er with integral restricted earth fault relay

5

A

23

25

27

24

26

28

23

25

27

24

26

28

23

25

27

24

26

28

B

C

Figure 4: Typical connection diagram for MBC H relays protecting a YD 11 transform er on a phase by phase basis

A

B

C

23

25

24

26

23

25

24

26

23

25

24

26

27 12 28

27 12 28

27 12 28

Figure 5: Typical connection diagram for MBC H 12 relays protecting a series reactor

6

Y(d1) YO A B C

Restricted E/F relay

27

21

23

25

22

24

26

28

21

23

25

27

22

24

MBCH 13

12

MBCH 13 28

26

21

23

25 27

22

24

26

12

12 28

MBCH 13

Figure 6: Typical conn ection d iagram for M BC H 13 relays protecting a Y(d) YO transform er w ith integral restricted earth fault relay

Y(d)YO A B C

21

23

25

27

MBCH 13 22

24

26

21

23

25

12 28

27

MBCH 13 22

24

12

26

28

21

23

25

27

22

24

26

28

12 MBCH 13

Figure 7: Typical connection diagram for M BC H 13 relays protecting a Y(d) YO transform er supplied from a ‘mesh’ busbar

7

Generator

21 N.E.R.

22

25 23 MBCH 13 26 24

27 1 2 28

Unit Transformer 21 22

25 23 MBCH 13 26 24 25 23 MBCH 13 26 24

21 22

27 1 2 28 27 28 1 2

Figure 8: Typical conn ection diagram for MBC H 13 relays protecting a generator/ transformer u nit

1

13

+

3

Vx

14

 –

5 Phase 'A' 12

2 4

10

6

13

1

14

3 12

5 Phase 'B' 2 4

10

6

All output contacts shown are instantaneously initiated for any internal fault condition when terminals No. 1 0 on each phase unit are connected together as shown. Correct phase indication is maintained.

1

13

3 14

5 Phase 'C' 12

10

2 4 6

Figure 9: Connection for six change-over tripping contacts for three phase tripping of  up to six circuit breakers showing correct connection of the screened lead on a three ph ase scheme

8

1

21 RL1-1

 I 3

22 23

T5

24 25

T4

26

T3

RL1 2

 I 2

18

19

20

21

22

23

24

25

26

27

28

Module terminal block viewed from rear

Output circuits

10

2 4 6 8 10 12 14 16

17

RL1-2

 I 1

Case earth 1 3 5 7 9 11 13 15

3 5 2 4 6

13 Input circuits

14

Trip output

Trip other phase +  –

Vx

12

Bias see note 2

Reset T2

9 Operate

27  I DIFF

RL2-1

RL2 1

11

Alarm

T1

28

Protective safety earth

Note 1: (a)

C.T. shorting links make before (b) & (c) disconnect

(b)

short terminals break before (c)

Note 2: Terminal 12 on each p hase assembly should be interconnected by a screened lead GJO1 53 0 01 with the screen connected to terminal 14.

Figure 10: Block diagram: Biased differential protection relay type M BC H 13 w ith three biased inputs

3

Differential current (x I n ) Figure 11: Typical percentage bias characteristic

=

2

Operate

  e    l  o  p   S    %    8   0

I1 + I2 + I 3 + I 4 + I 5 + I 6

1 Setting range (0.1-0.5)

 b l e A l l o w a  r o r  a t i o  e r  2 0 %  r

 o p e  2 0 %  S l 0

1 Effective bias (xI n ) =

2

3

I 1 + I 2 + I 3 + I 4 + I5 + I6

2

A

Figure 12: Typical magnetising inrush waveforms

B

C

9

Restrain

4

Figure 13: Magnetising current with transform er overfluxed

0

3

    )    s    e     l    c    y    c     (

Figure 14: Typical operating tim e characteristic

   e    m     i     t    g    n     i     t    a    r    e    p     O

2

1

Setting rang e 0 0. 1

0.2

0.5

1

2

5

10

20

50

100

Fault current (x In)

119 (1Ø) 83.5 (1Ø)

1 2 3 4 5 6 X 7 8 9

145

1 2 3 4 5 6 X 7 8 9 Primary tap s

4 off M5 clearance holes

1 2 3 4 5 6 X 7 8 9

1 17

Earth S1 S2 S3 S4 P1 P2

S1 S2 S3 S4 P1 P2

S1 S2 S3 S4 P1 P2

11,5

310 (3Ø)

1 45

343 (3Ø) M4 terminal screws

Figure 15: O utline details of single and tr iple unit auxiliary interp osing transform er assembly

1

2

3

4

5

6

7 X Flexible  jum pe r leads

S1

S2

S3

S4

P1

Output to relay

Figure 16: Winding arrangement o f  single pole of auxiliary interposing transformer

P2

Input from line CT's

10

8

9

Technical Data Ratings A C C u r r en t (I n ) Freq uency

1 A or 5 A 5 0Hz or 6 0 Hz

A uxiliary d c supp ly (V x )

Vo lta g e Ra ting (Vd c) 30 - 34 48 - 54 110 - 125 220 - 250

O p era ting ra ng e (V d c) 24 - 41 3 7 .5 - 6 5 8 7 .5 - 1 5 0 175 - 300

Minimum basic setting 1 0 % , 2 0 %, 3 0 % , 4 0 %, 5 0 % I n 4 I n up to throug h b ias currents of 9 I n , thereafter increasing g rad ually to 8 I n

Bia sed fea ture H ig h-set fea ture

at through bias currents of 14 I n High-set operation

Immunity to magnetising current inrush is guaranteed provided the first pea k of the w aveform is no g reater than 1 2 times the rated rms current.

Accuracy

±1 0 %

Op era ting chara cteristic

D u a l sl o p e , 2 0 % u p t o I n , 8 0 % a b o ve I n .

Opera ting time

Typically 10ms to 25ms

Number of current inputs

M B C H 1 2 - 2 b i a se d i n p u ts M B C H 1 3 - 3 b i a se d i n p u ts M B C H 1 6 - 6 b i a se d i n p u ts

AC thermal rating C o ntinuo us Sho rt tim e, a ll versio ns

M BC H 1 3 ,1 6 : 4 I n M BC H 1 2 : 2 In 1 0 0 I n for 1s w ith a m a x i m um o f 4 0 0 A

DC burden W i th o u tp u t H / A n o t p i c ke d u p D C vo lta ge ra ting (V) 30 - 34 48 - 54 110 - 125 220 - 250

Burd en a t up per vo lta g e ra ting (W ) A p p ro x 3 A p p ro x 3 A p p ro x 4 A p p ro x 8

D C vo lta ge ra ting (V) 30 - 34 48 - 54 110 - 125 220 - 250

Burd en a t up per vo lta g e ra ting (W ) A p p ro x 4 Ap prox 4 Ap prox 7 Ap p ro x 1 2

W i th o u tp u t H / A p i c ke d u p

AC burden Through current only (p er bias circuit) I thro - 1 x I n Bia s a nd d ifferentia l circuit o nly I d if f = 1 x I n 11

Ap prox 0 .1 5 VA ( I n Approx 0.30 VA ( I n Ap pro x 2 .8 0VA ( I n Approx 3.20 VA ( I n

= = = =

1 A) 5 A) 1 A) 5 A)

Tw o cha ng e-ove r self-reset tripp ing contacts per relay. (For 3 ph ase schemes relays can b e interconnected as show n in Figure 9 to p rovide instantaneous operation of all three sets of cha ng e-over tripp ing contacts.)

Contacts

O n e n o r m a l l y o p e n l a t c hi n g c o n ta c t per relay. M a k e a n d c a r ry : 7 5 0 0 V A fo r 0 . 2 s w i th m a x i ma o f 3 0 A a n d 3 0 0 V a c o r d c . C a r r y c o n ti n u o u sl y : 5 A a c o r d c B re a k : 1 2 5 0 VA a c o r 5 0 W d c r e si sti v e , 2 5 W , L/ R = 0 . 0 4 s. S ub j e c t to m a x i m a o f 5 A a n d 3 0 0 V. Durability Lo a d ed co nta ct U nlo a d ed co nta ct

1 0 ,0 0 0 o p era tio ns m inim um 1 0 0 ,0 0 0 o p era tio ns m inim um

Operation indicator

Light emitting diode (red), hand reset

Line current tra nsform er r equirem ents A pp lica tio n

Knee Po int Vo lta g e Vk Through Fault Stability N ote: Va lues to be a s given below, w ith minima of 60 In

for star -connected CTs and 1 0 0 for d elta connected CTs

In Tra nsfo rm ers

Vk

Generators Generator tra nsfo rm ers Vk O verall generatortr an sfo rm er/ u ni ts V k Motors Shunt reactors Series Reactors also Transformers connected to a M esh C o rner Vk having tw o sets of CT’s each sup p lying sep a ra te rela y inp uts Vk N o te: C T’s sho uld be o f equal ratio and magnetisation characteristic

X/ R

If

N M 2 4 I n [Rct + 2 Rl + Rt]

40

1 5 In

ኑ

2 4 I n [Rct + 2 Rl + Rt]

40

1 5 In

ኑ

4 8 I n [Rct + 2 Rl + Rt]

120

1 5 In

ኑ

2 4 I n [Rct + 2 Rl + Rt]

40

1 5 In

40

4 0 In

120

1 5 In

ኑ

ኑ

4 8 I n [Rct + 2 Rl + Rt]

{

W h er e:

In

= Rct = Rl = Rt = X/ R = = Ιf

Rated line CT seconda ry current (1A or 5 A ). Resistance o f line CT seconda ry w inding . Resistance of a sing le lead from line C T to relay. Effective resistance o f interposing CT w here used. M a x i m u m v a l ue o f p r i m a r y sy ste m r ea c ta n c e / r e si sta n c e r a ti o . M aximum value of through fa ult current.

Tab le 1 : C urrent Tran sforme r requirem ents.

12

Auxiliary interposing transformers

Nominal secondary current rating, I n 1A or 5A N ominal current ratios selectable in 0.58 - 1.73/ 1 4 % I n steps see Tab le 1 2 .8 9 - 8 .6 6 / 1 2.89 - 8.66/5 Note: Higher primary currents can be catered for. Refer to publication R-6077 Rated frequency

50/ 60Hz

Therm al withstand

4 x I n continuous 3 0 x I n for 10s 1 0 0 x I n for 1s with 400A m aximum

Effective r esistan ce Rt

2 .0 Ω for 0.58 - 1.73/ 1ratio 0 .2 Ω for 2.89 - 8.66/ 5 ratio 0.15 Ω for 2.89 - 8.66/1ratio

Insulation test voltag e

2 kV rm s 1 m inute, 5 0 H z

M a xi m um t er m in a l b lo ck w ir e si ze

8 4 str a nd , 0 .3 m m Ø

D im ensions

O utline drawings fo r single and triple group shown in Figure 15

Weig h t

4 kg single unit 12kg triple unit N umb er of turns

Primary top term inals

1/ 1A

Transform er rating 5/ 1A

5/ 5A

1 –2 2 –3 3 –4 4 –5 5 –6 X–7 7 –8 8 –9 S1 – S2 S3 – S4

5 5 5 5 125 25 25 25 125 90

1 1 1 1 25 5 5 5 125 90

1 1 1 1 25 5 5 5 25 18

Table 2: Interposing CTs: number of turns per tap.

High Voltage w ithstand

Dielectric withstand IEC 6 0 2 5 5 -5 : 1 9 7 7

2 kV rm s fo r 1 m inute between all term inals and case earth. 2kV rm s for 1 m inute between all terminals of independent circuits, with term inals on each ind ependent circuit connected to gether. 1 kV rms for 1 m inute across norm ally open contacts.

Hig h voltage imp ulse IEC 60 2 5 5 -5 : 1 9 7 7

13

Three p ositive a nd three negative impulses of 5kV peak, 1.2/ 50 µs, 0.5J between a ll terminals of the same circuit (except output contacts), between independent circuits, and between all terminals connected together a nd case earth.

Electrica l enviro nm ent DC supp ly interruption IEC 6 0 2 5 5 -1 1 : 1 9 7 9

A C rip p le o n D C sup p ly IEC 6 0 2 5 5 -1 1 : 1 9 7 9 Hig h frequency disturbance IEC 6 0 2 5 5 -2 2 -1 : 1 9 8 8 C la ss III

The unit w ill w ithsta nd a 1 0 m s interruption in the auxiliary supply, under normal operating conditions, without de-energising. The unit w ill w ithsta nd 1 2 % a c rip p le o n the d c sup p ly 2 .5 kV p ea k b etw een ind ep end ent circuits and case. 1 .0 kV pea k across terminals of the sam e circuit.

Fast transient disturbance IEC 6 0 2 5 5 -2 2 -4 : 1 9 9 2 C la ss IV

4 .0 kV, 2 .5 kH z a p plied directly to auxiliary supp ly. 4 . 0 k V, 2 . 5 k H z a p p l i ed d i r e ctl y to a l l inputs.

Surge immunity IEC 6 1 0 0 0 -4 -5 : 1 9 9 5 Level 3

2 .0 kV p ea k, 1 .2 / 5 0 µs betw een all group s and case earth. 2 . 0 k V p e a k, 1 . 2 / 5 0 µs between terminals of each group .

EM C c o m p l i a n c e 8 9 \ 3 3 6 \ EEC

C o m p lia nce w ith the Euro p ea n Co mmission Directive on EM C is claim ed via the Technica l Co nstruction File route.

EN 5 0 0 8 -2 : 1 9 9 4 EN 5 0 0 8 -2 : 1 9 9 5

G eneric Sta nd a rd s w ere used to esta b lish co nfo rm ity.

Product safety 7 3 / 2 3 / EEC

C o m p lia n ce w ith th e Euro p ea n Commission Low Voltage Directive.

EN 6 1 0 1 0 -1 : 1 9 9 3 / A 2 : 1 9 9 5 EN 6 0 9 5 0 : 1 9 9 2 A ll: 1 9 9 7

C om p lia nce is d em o nstra ted b y reference to generic sa fety sta nd ard s.

Atmospheric environment Temperature IEC 6 0 2 5 5 -6 : 1 9 8 8 IEC 6 0 0 6 8 -2 -1 : 1 9 9 0 IEC 6 0 0 6 8 -2 -2 : 1 9 7 4

Sto ra g e a nd tra nsit -2 5 °C to + 7 0 °C O p e r a t in g -2 5 °C to + 5 5 °C C o ld D r y hea t

Humidity IEC 6 0 0 6 8 -2 -3

5 6 d a y s a t 9 3 % RH a nd 4 0 °C

Enclosure p rotection IEC 6 0 5 2 9 : 1 9 8 9

IP5 0 (d ust p ro tected )

Mechanical environment Vibration IEC 6 0 2 5 5 -2 1 -1 : 1 9 8 8

Resp o nse C la ss 1

Seismic IEC 6 0 2 5 5 -2 1 -3 : 1 9 9 3

C la ss 2

14

Cases

52

Relays type M BCH a re housed in size 4 cases as show n in Figure 17 .

4 holes Ø4.4

97

23.5

159

168

Push button projection 10 max.

32

99 Panel cut-out: Flush mounting fixing details

212

25 min.

157 max.

177 Reset 77

Flush mounting

11

All dimensions in mm

Figure 17: Case outline size 4

Informa tion required w ith order N ote: 3 single-pha se M BCH relays are required for a 3 -pha se scheme. Please state total num ber o f sing le-pha se relay s required . Rated current I n Rated frequency Auxiliary dc supply voltage V x N umber o f current bias inputs: M BC H 1 2 : 2 i n p ut M BC H 1 3 : 3 i n p ut M BC H 1 6 : 6 i np u t Auxiliary interposing transformer Rated current I n Current ratio M ounting: single or triple unit

Associated Publications Interp o sing m a tching C Ts fo r use w ith M BC H rela y s

R6 0 7 7

M ID O S sy stem

R6 0 0 1

M M LG / M M LB test b lo ck/ test p lug

R6 0 0 4

15

ALSTOM T& D Protection & Control Ltd S t Le o n a r d s W o r k s , S ta f f o r d , S T1 7 4 L X En g l a n d Te l : 4 4 (0 ) 1 7 8 5 2 2 3 2 5 1 Fa x : 4 4 (0 ) 1 7 8 5 2 1 2 2 3 2 Em a i l : e n q u i ri e s@p c s .a l st o m . c o . uk I nt er n et : w w w . a l st o m . c o m  © 1 9 9 8 A LSTO M T& D Pro tec ti o n & C o nt ro l Ltd O u r p o l i c y i s o n e o f c o n t i n u o u s d e v el o p m e n t . A c c o r d i n g l y t h e d e s i g n o f o u r p r o d u c t s m a y c h a n g e a t a n y t i m e . W h i l st e v e r y e f fo r t i s m a d e t o p r o d u c e u p t o d a t e l i t e r a tu r e , t h i s b r o c h u r e s h o u l d o n l y b e r e g a r d e d a s a g u i d e a n d i s i n te n d e d f o r i n f o r m a t i o n p u r p o s e s o n l y . I ts c o n t e n ts d o n o t c o n s ti t u te a n o f f e r f o r s a l e o r a d v i c e o n t h e a p p l i c a t i o n o f a n y p r o d u c t r e f e r r ed t o i n i t . ALSTO M T&D Protection & Co ntrol Ltd canno t be held respo nsible for any reliance on any d ecisions taken on its contents without specific advice.

Publication R-6070 L

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Printed in England.