Siemens 7 sk 88 a series User manual

SIEMEt~S

7 SK

88

..

-

..

A

IDMTL

OVERCURRENT

RELAY

Installation and maintenance instructions

."

.

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.........

:.:.:.:

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:.

..

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•.

w.

:.:

;.;

••

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..

"

,

I•

I

•

T

I

t

-<

t

•

:

I'

" •

Protective

relays

Static

single

ph

as

e ,

10M

TL

overcurrent

rei

a y

7

SK

88.

• •

.A

Installation

and

maintenance

instructions

...

"'!f~~.

Contents

Survey

of

types

Description

Acceptance

check

Installation

Setting

the

relay

Auxi

I

iary

su

pply

Commissioning

Maintenance

Technical

data

Plug

setting

link

Page

2

3

7

10

13

15

17

Test

sockets

Contact

Time

multiplier

I >

Target

indicator

I >

High

set

I»

Target

indicator

I»

Reset

(4)

E14041-F7230-U211-Al-7600

i

I

i

:/

:\

,\

I

,

I

'f

'I

J

- 2 -

1.

Survey

of

Types

(ordering

codes)

Inverse-time

overcurrent

relay

system

7SK88

In

a

compact

case

"

For

Currel'll

Ir

anslor

mer

rated

Curre

Setting

range

of

751<88

Supply

voltage

UV

60

V d,c.

\',0

V

d.c.

Supply

from

Weigl'll.

1125

V

d.c

1220

V

d.&:.

current

I'll

transformer

approx

Order

No.

Order

No.

Order

No_

Order

No.

A A

(for

the

Order

No,

suffix

see

below)

kg

--

01

to

0.4

75K8.12-

••

75K"1~

.•

75K

••

14-

.•

75K8.15-

.•

75KII

11-

..

02

to

0_8

22-

••

2~

.•

24-

.•

25-

••

21-

..

1,5

lor

5 *

lor

5 * 0,5

to

2

32-

••

3~

••

34-

.•

35-

••

31-

..

I

CT.

powerd

5

1 to 4

2_5

to

10

4 to 18

42-

..

4~

.•

52-

.•

5~

..

12-

.• Uo-

••

44-

••

45-

.•

41-

..

version

1,8)

54-

.•

55-

••

51-

..

64-

.•

a5-

.•

61-

..

•

In

this

case,

the

5 A

c.t.

shall

be

in

the

earth

fault

circuit.

Thus a

higher

sensitivity

is

achieved.

Order

No.

suffix

for7SK88

Characteristic

and

optional

element

I~

--------------------.--

--------~----

Characteristic

Short-circuit

instantaneous

trip

I~

not

fitted

Order

No.

suffix

7SK88

••

-

-------------------------

Inverse

1DA

1EA

Very

inverse

3DA

3EA

~E~x~t~r~e~m~e~1~y~~i~n~v_e_r_s_e

____

4_D_A

______________________

4EA

Continuous

technological

progress

and

modernisation

of

components

may

necessitate

production

modifications.

These

modifications

do

not

affect

relay

performance

and

are

recorded,

for

internal

purposes

only,

by two

letters

after

the

code

(MLFB)

number

(e.g.

7SK8818-1DA/DD).

Test

adapteJ

for

7SK88

7XV8110

1XV8120

Test

adapter

cable

with

banana

plugs

Test

adapter

cable

with

Harting

plug

for

testing

with

7VP461

(

• - 3 -

2•

Description

Relay

75K88

i~

a

self

contained,

single

phase

overcurrent

protec-

tion

device

with

inverse

definite

minimum

time

characteristics.

Its

applications

include

primary

protection

of

radial

networks

in

distribution

and

industrial

installations

and

back-up

protec-

tion

for

distance

relays

and

similar

schemes.

The

7SK88

can

be

supplemented

by

the

directional

relay

7SP88.

This

combination

provides

a

directional

inverse

time

protection

system

for

the

protection

of

ring

mains

and

parallel

lines

or

transformers.

~

It

can

be

equipped

with

a

high

set

instantaneous

element.

Al-

though

designed

principally

for

operation

from

an

auxiliary

d.c.

power

source,

a

version

is

available

for

current

transformer

de-

rived

auxiliary

power,

allowing

use

in

installations

where

sepa-

rate

d.c.

power

is

not

provided.

•

3..

Acceptance

Check

On

unpacking

the

relay,

check

the

nameplate

to

ensure

that

the

model number and

rating

agree

with

the

requirements.

Check

that

there

are

no

signs

of

physical

damage.

The

relay

has

been

tho-

roughly

works-tested

and

calibrated.

It

contains

no moving

parts

and

is

therefore

ready

for

installation

without

adjustment.

If

the

target

indicator

shows

"tripped"

(red)

when

delivered,

this

is

unimportant

since

it

can

be

reset

as

soon

as

the

auxiliary

supply

voltage

is

connected

or,

with

the

C.T.

powered

version,

when

at

least

20 J

load

current

flows

in

the

primary

circuit.

4.

Installation

The

case

is

designed

for

flush

mounting

in

a

panel

or

support

plate

of

any

convenient

thickness

(fig.

1)

and

at

any

convenient

angle

in

a

location

reasonable

free

from

excessive

heat,

dust

and

moisture.

It

can

be

secured

by two

machine

screws

(H6),

with

nuts,

top

and

bottom

of

the

front

bezel

•

- 4 -

External

connections

are

at

the

rear.

These

are

post

type

ter-

minals

fitted

with

slotted

head

screws

and

clamps.

Flexible

or

stranded

conductors

must

be

fitted

with

crimped

ferrules.

All

terminals

are

permanently

numbered.

For

front-access-only

cabi-

nets,

the

relays

can

be

mounted on

hinged

plates

or

frames

for

access

to

the

terminals.

The

units

are

not

sensitive

to

shock.

(Tested

to

withstand

2

G).

The

internal

carrier

is

secured

by

screws

from

the

back

and

supports

the

plug-in

printed

circuit

board

on

the

right

hand

side

which

carries

the

static

component

circuitry.

CD

fixing

screws

for

internai

carrier

Fig.

1:

Inverse-time

overcurrent

relay

7SK88;

compact

case

for

switchboard

panel

flush

mounting

With

the

current

transformer

short-circuited

and

the

auxiliary

supply

de-energised,

connect

the

C.T.

leads

to

terminals

3 and

4 and

the

auxiliary

supply

to

terminal

9

(+

ve)

or

terminal

7

(if

220 V

model

is

used)

and

terminal

8

and

12

(-

ve).

The 220 V

model

is

fitted

with

a

dropper

resistance

which

is

located

at

the

main

terminals

for

good

heat

dissipation.

This

resistance

can

attain

a

surface

over-temperature

of

200 °c -

it

must be

ensured

that

the

resultant

heat

can

properly

dissipate

and

is

not

obstructed

by

adjacent

wiring

or

other

restrictions.

I

~

•

, .

L+

Test

cUrTent

injection

T Reset

L+

lS

M

L-

1S

§

- 5 -

I =

TM

=0,05-0,5

Bushes

on

Frontplate for

II

~

TM

:

0,

SS

-1

response

time

measurement

I>

Q

Br.1

Rel.A

I»

¢

ReLB

~-~

---5chauzeichen

1:

Targetindicator

-c:J-

§

~

t-....:==:J

J

L

___

.

__

.

____

'

__

0 p./JPo

__

Br~~_.

__

._J_::'_.

__

~

__

.

4/2216

•

"dropper"

resistance.

220 V

model

only

•

Fig.

2:

Internal

Schematic

1SK88xx-xxA

If

the

target

indicator

shows

"tripped",

it

can

now

be

reset

on

application

of

the

auxiliary

supply

or,

with

the

C.T.

powered

version,

when

at

least

20

~

load

current

flows

in

the

primary

circuit.

With

the

C.T.

powered

version

terminals

8

and

9

remain

free.

In

planning

the

tripping

circuits,

ensure

that

the

rating

of

the

output

relay

contacts

are

not

exceeded.

L1

L2 L3

J

~

II

I

r-

~

52

1\

L....

I-

DC

Trip

+----4

.......-

50/51-1

52

Fig.

3:

Fig.

30

current connections

3 51-'

50-;:4

I

__

J

3

51-2

sO-2l4 3

51-4

50--4;4

_J

.

__

J

3

51-3

50-314

J

4/2214

Fig.3c

output

contact

connections

5

555

Alarm

4/2214

- 6 -

Fig.3b

auxiliary

supply connections

(nat applicable

to

C.T.

powered version)

DC

aux.

bus

+--~----~----~------

9_

SO/51

-1

8

9*

50151

-3

8

fr terminal 7

for

220V

mo

del

Legend:

51

-1

o/e-

relay

75K

88

51-2

ole-relay

75K

88

optional

51-

3

ole-relay

7

5K

88

51- 4

01

c-relay

7

SK

88

optional

52

Circuit breaker

50

-1

high set element, optional

SO

- 2

high

set

element. optional

50

- 3

high

set element, optional

50- 4 high set

element,opti~nal

5 5 5

Auto-

rec(ose

relay or

similar

or

alarm

External

Schematic

-7SK88

Relay

d.c.

powered

or

C.T.

powered

version

(

•

- 7 -

5.

Setting

the

Relal

5.1

OvercurrentElement

Remove

front

cover

by

releasing

captive

screws

top

and

buttom.

Removal

of

the

cover

automatically

short

circuits

the

input

from

the

associated

current

transformer

and

disconnects

it

from

the

internal

circuits.

Thus

the

accessible

components

on

the

relay

front

are

entirely

volt-free.

When

used

for

phase

overcurrent

protection,

one

or

two

further

7SK88

relays

are

installed

in

the

remaining

phases.

These

remain

operative.

The

overcurrent

element

(I

)

has

two

settings:

Current

setting

(Ip)

(Plug

setting)

10

-

40

~,

20

-

80

~,

50

-

200

~

or

100

-

400

~

in

7

equal

steps

selected

by

rotary

link

on

the

front

plate.

This

setting

values

on

the

front

plate

are

given

in

amps

secondary.

The two

screws

must

be

re-tightened

carefully.

The

link

must

not

be

left

in

an

open

position.

This

setting

allows

the

overcurrent

pick-up

v~lue

to

be

selected

with

respect

to

circuit

rated

load

and

current

transformer

ratio

e.g.

C.T.

ratio

circuit

full

load

current

required

pick-up

value

(for

example)

relay

range

120

Ip

= 200 x 5 x

1.25

=

3.75

A.

Nearest

setting

=

3.75

A (75

~)

•

200/5

A

120

A

1.25

x

full

load

current

50 -200 J

(i.e.

2.5

to

10

A)

- 8 -

5.2

Time

Multiplier

(TM)

Set

by

slotted

rotary

dial

on

the

front

plate;

two

ranges

are

available:

0.05

to

0.5

in

steps

of

0.95

(with

selector

plug

on

PCB

in

position

I -

as

set

in

the

factory),

alt.

0.55

to

1

in

steps

of

0.05

(with

selector

plug

on

PCB

in

position

II).

The

adhesive

strip

for

the

T.M.

scale

situated

on

the

rear

of

the

front

plate

must

also

be removed

and

fixed

on

the

front

to

cover

the

printed

letters

TM

(see

fig.

6).

Thus

the

alteration

of

the

TM-setting

range

is

made

visible.

The

TM-setting

allows

selection

of

the

time

scale

against

which

the

inverse

characteristic

is

set

(see

fig.

4).

The

intermediate

.

curves

given

by

the

0.05

steps

lie

between

the

curves

shown.

The recommended

grading

time

between

successive

relays

is

0.3

to

0.4

sees.

60

1

~o

30

I

20

I

!sI

10

8

6

4

3

2

1

08

0.6

0.4

0.3

0.2

0.1

0.08

0.06

0.04

0.03

0.02

00

,

r-

l-

0.5

.,,"

r--- 1

-I

Ij~--

. .- I -

..

I-'

-

--

---

.

--

I-

b=

I

~

" '

=:=

.

~~

'~I.."-"

==

",~y

1-'-

r-==

.~-

,.

'.

::-..~

I-r-

I '

~~

....

~-r-

TM

\.1

.

~~

I~~~R.:~

~

NI':

r-.I~'

0.8

"

I~

k.~~

0.6

0.5

0.9

0.7

0.4

"'

.......

~

I

.....

0.3

" I I

f"""oo.,.\

~

I

No-

I I ,

.........

0.2

,

~

-

...........

0.1

..........

II

...............

..........

0.0

5

, . I

I

\

I

2

3~S

10

20

lllp-

inverse

(to B.S. 142)

1:

Current

in

A

60

r

30

20

t

Is)

10

8

6

4

3

2

1

0.8

0.6

0.4

0.3

0.2

0.1

0.08

0.06

0.04

0.03

0.02

0.01

0.5

I

.'tt'

!J,:

Pick-up

setting

in

A

TM:

Time

multiplier

adjustable

on

front

panel.

to

B.S. 142

,

I

:Ir.'~r-

I

'Lj-o-

r

--f--

-

!

~

It

f--r-

§

I " t

t-r-

I. -

=~

i

1-f--

i-e-

~

- -

'-r-

-+-==~

\\

-

r-

I \'\" I --

\\'~~t

~.

--

\.

,\~

.--

-

~

,-

-

\:\\'\.

\!..

.-

-

1\

\

\\~~"\..

\

\i\\.~.~

~

~~-

\\

~\i\'~

\

I\\K~

, .

d,

'\

\.

\

'\I

"-

N ,

,

I

~

N

t~

1\

I

INJ

, , H

I I

I

~~

~.~

'"""'-

~

..........

'-

r-

"'"

-"""t--

:1-

-

.......

,

........

.-

r-

1M

1.0

0.9

0.7

..M..

0.6

0.5

0.4

0.3

0.2

0.1

o.

05

2

.3

..

5

10

20

lIJp

-

very

inverse

Fig.

4:

Overcurrent

time

characteristics:

t = f

II/Ip)

for

the

inverse-time

overcurrent

relay

7SK88

3

'I

1\ 1\

\.\~

elllremely

Inverse

()

o

•

..

•

i

•

I

0·05

-

O·

5

II

O·

55-

1·

0

TM

-:0:·

0,05

0,5

0.05

to

0.5

(as

delivered)

- 9 -

TM

+

0,5

adhesive

strip

"·0:'

0,05

0,5

0.5

to

1

(altered)

Fig.

5:

TM

range

selector

plug

Fig.

6:

TM

setting

range

5.3

Instantaneous

Element

(I»)

When

fitted,

is

set

by

slotted

rotary

dial

on

the

front

plate:

Range: 4

to

20

times

1p.

The

setting

is

continuous

i.e.

if

1p

set

at

3.75

A = 125 %

circuit

r.1.c.

(as

in

current

setting

example)

and

I»

set

on

10,

then

instantaneous

element

operates

at

37.5

A

(12.5

x

f.l.c.)

within

approx.

15

ms.

If

the

operating

time

proves

to

be

too

short,

it

can

be

extended

by

inserting

a

capacitor,

on

the

solder

tags

marked

C12

on

the

printed

circuit

board.

A

dry

type

tantalum

capacitance

is

recom-

mended

(e.g.

Siemens

UBB-B45178). The

required

capacitance

for

a

particular

time

delay

is

given

in

fig.

7;

a 30 V

device

is

adequate

•

If

the

solder

bridge

2

is

inserted

on

the

p.c.b.

then

the

trip

from

the

high

set

element

I

is

blocked

(as

delivered

the

bridge

2

is

not

inserted)

•

Fig.

7:

Instantaneous

element

time

delay

value

of

capacitance

C12.

6.1

Auxiliary

Supply

-10 -

The

relay

measuring

element

requires

auxiliary

power

(see

survey

of

types).

In

the

current

transformer

powered

version,

an

additional

internal

circuit

powers

the

measuring

element

from

the

C.T.

secondary

cur-

rent.

The

output

relay

(tripping

relay)

contacts

remain

volt

free,

an

auxiliary

supply

is

still

required

for

the

circuit

breaker

trip

coil.

o

~

!

t

I

t

,

t

I

•

t

-

11

-

4t

As

a

further

alternative,

the

power

circuit

breaker

trip

coil,

for

example

Siemens

type

3AS1102 (H86w),

can

also

be

operated

directly

from'

the

C.T.

secondary

current

when

an

auxiliary

supply

is

not

available.

An

auxiliary

C.T.,

with

saturation

characteris-

tic,

type

4AM5070-BAB,

connected

in

the

C.T.

circuit

as

in

fig-

ure

8,

gives

the

required

power

(up

to

20

VA

at

0.5

or

1

A).

For

reliable

operation

adequate

primary

current

(greater

than

full

load)

is

necessary,

thus

this

method

is

not

suitable

for

earth

fault

tripping

if

the

earth

fault

current

is

less

than

full

load

current.

In

such

cases

an

auxiliary

supply

is

essential.

•

6.2

Current

Transformer

Selection

The

phase

overcurrent

relay

has

a

very

low

burden.

Thus,

as

a

general

rule,

a 15

VA

10P10

(knee

point

voltage>

190 V

for

1 A

resp.

38 V

for

5 A

transf.

second.

rating)

transformer

is

suf-

ficient.

In

many

cases,

a

lower

output

will

suffice.

This

can

easily

be

checked

by

the

general

principles

applying

to

th~

6al-

culation

of

C.T.

burdens.

When

used

as

a

ground

fault

protection

relay,

the

low

burden

cha-

racteristic

allows

the

relay

to

be

set

at

the

very

sensitive

cur-

rent

level

of

10 -

40

~

IN

even

when

used

with

C.T.'s

of

standard

output

•

If

the

trip

coil

has

to

be

operated

by

aux.

C.T.

4AM5070-8AB

a

minimum

C.T.

output

of

30

VA,

10P10

Is

required.

L1

L2

l3

u

~

Ai

~~xiliary

(.t.

·l

I 4AM5070-8AB

Ka

_La

i

- I

Kb

_lb

Ke

_Le

.

--

Kd

l = .Ld

-

12

-

3

51-1

50-1

4

3 51-2 50-2

·4

• 1

1111111111

4/2215

iI 3

51-3

50-3

4

..

\--

~-,

-~-T-E9

52

L_~

...,

re 5

r---j---4t relay trip

50-1

!jS1-1

contQct~-

2connect In

parcfel.

~.

~

.

Legend

51-1 o/e- relay

7SK88

51- 2

ole

-relay 7

SK

88

optional

51- 3

ole

-relay 7

SK88

52

Circuit breaker

50-1 high set

element,-optional

50

- 2 high set

element,

optional

50

- 3

high

set

element,

optional

* Zenerdiode

Fig.

8:

External

Schematic

of

1SK88

relay

-

C.T.

powered

version

with

tripping

from

C.T.

supply

(

• -

13

-

7.

Commissioning

Firstly,

chec~

that

the

connect,ions

of

current

transformers,

tripp-

ing

and

alarm

connections

as

well

as

the

polarity

of

the

auxiliary

supply

are

correct:

1.

Check

ratio

and

connections

of

C.T.s

}

(fig.

3

or

8)

Check

auxiliary

supply

voltage

and

polarity

2.

Check

response

of

relay

at

your

settings:

CAUTION:

When

removing

or

restoring

connections,

the

accepted

safety

practices

and

regulations

must

be

observed.

Dur-

__

ing

all

measurements

take

care

that

the

thermal

capacity

is

not

exceeded

(see

fig.

10).

•

a)

Remove

transparent

front

cover.

The

external

C.T.

is

automati-

cally

short-circuited

and

disconnected

from

relay.

b)

Using

test

plug

with

the

associated

cable

7XV81

(which

includes

the

trip

circuit

output

-

see

figure

9)

check

the

operating

time

at

one

or

two

points

on

the

characteristic,

one

with

a

test

current

of

approximately

four

times

plug

setting

and one

at

a

higher

value

if

possible

(Siemens

test

sets

7VP44

or

1VP461

may

be

used

for

this

purpose).

The

permissible

toler-

ance

should

not

'exceed

~

20 %

(according

to

BS

142) •

Should

larger

tolerances

exist

then,

as

a

first

step,

the

test

set-up

should

be

checked:

superimposed

load

current

shunt

circuit

for

test

current

}

not

possible

if

1XV81

is

used

for

testing

test

current

not

constant

during

relay

delay

time

test

current

not

injected

(in

particular

for

C.T.-powered

relays).

If

after

checking

the

above

points

an

excessive

tolerance

exists

then

the

complete

relay

should

be

returned

for

repair.

Do

not

attempt

recalibration.

3

4·

5.---

....

6'

2----~

relay

input

C.T.

1

__

--------~

4/2215

Test

current injection

Response

time

measurement

y

b

-14 -

br

g

plugs'

Fig.

9:

Diagrammatic

representation

of

effect

of

inserted

test

plug

7XV8~10

300

100

50

30

10

5

3

':

i-

-

...

~~

- 1 I

__

.

:'-1:

Ln

~~--"

.-

-~

j-f'I:--:

-.

,~

...

--.

-:..~

..

.,

"

"i

':

10

,-ijr-

-~L~T:i_-ic:-:J;i;:~lJ+:-~n-;:::

'

-1

1

:-

i -

,---1

I

10

100

Imox/5~

...

;...

.

~

:.

...

l

"

...

:("1

•

~..

".

'..l":':

.-

~

~o

-:

7

~.;

I

~

",

I

-r

t,

I

1

I

4-10

+~J

-t-8

+~

..,..~

1

T~

~-

..

i:

1,

1000 I

- ; •

r-

~

Fig.

10:

Thermal

withstand

of

current

circuit

1SK88

• -15 -

c)

The

response

of

the

high

,set

element

may

be

similarly

checked

•

The

permissible

pick

up

tolerance

should

not

exceed

+

10

%

..

3.

Check

correct

functioning

of

tripping

circuit

(with

circuit

breaker

if

possible)

and

indicating

circuits

all

in

conjunc-

tion

with

directional

relay

7SP88

if

fitted.

4.

Restore

equipment

to

proper

operating

condition.

Important:

After

testing

the

relay

it

is

essential

that

the

correct

type

of

plastic

front

c?ver

is

refitted.

Check

that

the

cover

has

the

~

engraved

type

designation

7SK88

••

-

.•

A.

•

8.

Maintenance

The

unit

has

no

particular

maintenance

requirements.

All

measure-

ment

circuits

are

static

"and

maintenance

free.

The

output

relay

is

covered

with

a

transparent

plastic

wrap

(cover)

•.

An

occasional

functional

test

is

recommended.

The

tripping

circuit

and power

Circuit

breaker

should

be

included

in

the

test,

together

with

any

associated

elements

(e.g.

7SP88

directional

element)

•

In

the

event

that

a

component-becomes

damaged

or

unservicable

the

complete

PCB

or

assembly

can

be

easily

replaced

without

re-

calibration

•

-

16

-

The

following

standard

replacement

parts

are

available:

Description

Transparent

front

cover

Printed

circuit

board

(complete)

Measuring

element

inverse

very

inverse

extremely

inverse

with

high

set

element

inverse

Important.:

very

inverse

extremely

inverse

Ordering

Code

C73207-A235-B66

C73207-A235-B221

C73207-A235-B225

C73207-A235-B227

C73207-A235-B222

C73207-A235-B226

C73207-A235-B228

These

replacement

parts

only

apply

for

the

relay

type

7SK88

••

-••

A.

In

the

case

of

relays

of

an

earlier

series

the

complete

relay

must

be

returned

for

repair.

•

Techn

i

cal

Data

Auxiliary voltage

UN

Operating range

Max.

penn.

residual

ripple

Current

demand.

operated, including

output

relay

at

UN

=110-220 V

at

~

=

60

V

Test voltage

at

50

Hz

for

60

s

Impulse voltage

test

to

IEC

225-4

High~frequency

test

1

MHz,

400/s

Limiting temperature

for

operation

for

storage

and

transport

Case

Weight (approx.)

Material

Colour

Degree

of

protection

(IEC

144)

Humidity

class

ace.

DIN

40040

Mechanical withstarxi ace.

DIN

60046·

for

operation

for

storage

and

transport

Specifications

or

recommendations

-

17

-

V

d.e.

60, 110,

125,

220

(preferred

values)

rnA

kV

kg

80

-

115

)

10

)

ca.

60

ca.

75

2

5

2.5

(for

preferred

values)

-5

0

Cto+50oC

-25

°c

to

+65

°c

1.5

(CT

powered

version 1.8)

Makrolon,

fibreglass

reinforced

Stone grey,

RAL

7032

IP

54

(termdnals

IP

04)

class

F,

i.e.

75

J average

95

%

for

max.

3

months

p.a

•

10

••••

60

Hz:

0.035

mm

extentricit~

60

•••

500

Hz:

0.5 g

5

....•

8

Hz:

7.5

mm

extentricity

8•••

500

Hz: 2 g

mc

225-4,

VDE

0435,

BS

142

Connection

to

current~transformer

Rated Burden

(c.

t.),

typical

,values,

based

on

min.

setting

c.t.

powered

version

c.

t.

powered

version plus

c.

t.

operated

trip

coil

Lilniting withstand values

for

1 sec

for

10

sec

continuous

Overcurrent element I

Plug

settings

Setting

ranges I

in

A

p

Pick-up

tolerance

Drop-out

to

pick-up

ratio,

typical

Drop-out time,

typical

Overshoot time

Time

multiplier

TM

Characteristics

•

preferred

values

A

J

ms

lOS

1 A

or

5 A

0.5

VA

5

VA

30

VA

minimum

-

18

-

50

or

60

Hz

100

x Ip

min

(max.

250 A)

30

x Ip min

(max.

15

A)

5 x Ip

min

(max.

16

A)

,7

positions

at

equal

intervals

0.1 -

0.4

0.2

-

0.8

*)

0.5

-

2.0

*)

1 - 4

2.5

-

10

.)

4 -

16

+

15

- 0

0.95

s

30

< 2

0.05

to

1

in

steps

of

0.05

normal inveae

(BS

142)

very

inverse

extremely inverse

curve according

to

characteristic

(see Fig.

4)

t

,

1

t

I

t

•

Instantaneous (hiSh

set)

element I »

setting

range

pick-up time

(typical

values)

at

1.1

~

IDS

at

2 Ip

IDS

with time delay (with

addi-

IDS

tional

capacitor

C12

on

PCB)

pick-up

tolerance

drop-out

to

pick-up

ratio,

typical

drop-out time

transient

overreach

(if

C12

~

1

}IF)

Out

p.1t

relays

(2)

each with:

Number.

and type

of

contacts

Make capacity 0

Break capaci

ty

o·

Switching

current,

continuous

for

0.5"

s

Switching voltage

(a.c.

or

d.c.)

IDS

W

or

VA

W

or

VA

A

V

-

19

-

4xto20x~

(stepless)

20

15

50

-

400

10

%

of

setting

0.95

40

less

than

10

2 N/O; silver-cadmium oxide

1000

30

5

30

250

Siemens 7 SK 88 A Series User manual

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