CALOR EMAG bag.1.pdf

8/9/2019 CALOR EMAG bag.1.pdf

1/10

~':, [fAA

'. ,

~

;t

I ~ ~YJ

riA

'

.

. .

~/

.

~

.

:

.

'

.

')

..

~ HOCH

UND NIEDERSPANNUNGS-SCHALTGERATEUND-SCHALTANLAGEN

.( CAlOR-EMAGE-AG ' Post'ach 1220 ' D'4Q30 Rati ge 1

I ' Table of Contents t Group a

.

~ 4

.~'.. .

.

4 8

.

2

...

? ~ 4~8.3

.\ ~ 4.8.4

4.8.5

'S:

f,../,;


2/10

econd ry Thermal

Relays type ST

for a c or d c

4 8 1

For overlo


3/10

-

BROWN, BOVERI .CO., LTD., BADFN, SWITZERLAND

ontents

Notes

A. Purpose

B. Properties

C. Design and principle

Thermal part . .

Tripping characteristics. ,

Instantaneous limit-current trip

Front plate

Signals.. . , . . .

Contacts . . . , .

Casing and terminals

D, Settings on the relay

Time constant (choice, setting, measurement)

Set current . . . . , . . . , .

Temperature rise for pick-up, ,

Instantaneous limit-current trip

Page

4

4

5

8

13

14

14

14

14

14

15

15

16

E Specia designs

Description of relays type'sSTa, STb, STc, STd, STe, STf, STh, STi, STm,

STn, STp, STr, STg, STk, STs. , 16

Table showing contact connections 17

F. Tableoftypedesignations.. . ,. . . . 19

G. Application


4/10

BROWN, BOVERI & CO., LTD., BADEN, SWITZERLAND

Notes

Purpose

The secondary thermal relay type ST is used for

overload protection of electrical equipment of all

kinds, such as machines, transformers, cable, etc.

Evenwhen the load is variable, its temperature rise

closely follows that of the object or part of the in-

stal atlon being protected. When the set tempera-

ture rise is exceeded, the relay actuates its contact

and thus closes a warning or tripping circuit. Until

this limit Is reached, It permits any load and thus

allows full advantage to be taken of the thermal

capacity of the protected object.

~vercurrent r l ys are not suited to this task as

they do not take into account the thermal properties

of the protected object.

The secondary thermal relay type ST is also

equipped with an overcurrent relay independent of

the thermal part, which picks up immediately a set

current is exceeded. This Is known as the IImit-

current trip and may be used for instantaneous

short-circuit protection or, in conjunction with a

separate time-lag relay, for overcurrent-time pro-

tection (see examples of connections on page 28).

The a. c. design of the relay is intended for con-

nection to currtlnt transformers having a secondary

current of 5 A, while the d. c. version is connected

to a shunt, or parallel to the winding of a machine

with the voltage drop at full l.oad of at least 1.75V.

Definition of temperature rise

The temper:Jture rise which concerns the rdlay is

the difference between the temperature of the pro-

tected object when loaded and the ambient tem-

perature.

()

57 IS V

Fig. 1

Secondary thermal

rel y

type ST

in cI '.ing . for flush mounting

with reu connection

a - Signal reset button

B Properties of the

econd ry

Thermal Relay type ST

The relay offers the following features:

It is a good thermal overload protection and ren-

ders superfluous such foreign elements as thermo-

couples, detectors, auxiliary leads, etc., in the pro-

tected object.

It indicates the momentary temperature rise and

is thus a means of checkin~ the temperature of the

protected object at any time without any special in-

struments.

It indicates the maximum temperature rise by

means of a pointer which can be reset after reading.

Simultaneously it affords short-circuit protection

by means of an overload element which can be set

over a wide range; this is known as th) limit-

current trip.

It can be adapted to the protected object over a

wide range since the thermal time r;onstants are

variable between 20 and 110 min.

It has a very low consumption.

It has a visiole signal both for the thermal and

overload trip.

The type designation is ST. Changes in the

internal connection and certain special designs are

denoted

y

additional small letters (see page 16,

Special designs).


5/10

Ii

,..

,

'''

.,

, '~

,-

-i

~

.

1-'

Fig.4

Defining the time constants

.conducted by it to the cool:ng medium (air and/or

water). The time constant of this second transfer

of heat is of the order of 1-2 hours. Thus the curve

showing the temperature rise of the transformer

copper can be treated as the sum of two exponen-

tial curves with different steady-state temperature

rises, one having a small time constant, the other a

. large one. Ifthe current, and thereby the losses in

the transformer are abruptly increased, the copper

rapidly assumes its steady-state temperature re-

lative to the oil; the rise in temperature of the oil,

however, is much slower. If a definite upper limit

is stipulated for the temperature rise inth( copper,

the permissible duration of this load is primarily

min

120

100

80

60

40

20

o

~o 40 60

80 100 '/,

Fig.5

Tripping time of the secondary thermal relay type ST. compared

with th.. permissible duration f an overload of a 2OQ-kVA

transformer

Legend:

1 R lay

2 Transformer

I

I

I

I

\

\

I

\.

... 1

I

2

.

I

-

h-.

5 3 47 1


7/10

.'.:

.

'.

)j,

~

-


governed y th smaller time constant of the heat

transfer between copper and oil, but for a small

overload it is governed bythe larger time constant

of the transfer from oil to coc-Iant.The conditions

are similar for cables and rotating machines.,

The suitability of the secondary thermal relay

type ST for supervising objects whose temperature

rise follows the r'lles outlined above Is based on

the fact that the temperature rise of its measuring

elem~nt is largely governed by a series connection

of two heat transfers, the first having only a mode-

rate temperature difference and small time con-

stant between the heater element complete with

measuring element and heat carrier, the second

having a larger temperature difference and large,

variable time constant tor the transfer between the

heat carrier and the atmosphere. Hence the curves

for the temperature rise of the thermal relay type ST

exhibit a small initial time co ,\stant (init ial tangent)

and a high sustained time constant (until 63% of

the steady-state temperature rise is attain9d); the

latter is known as

T the time constantof the relay.

The temperature rise of the relay with respect to

time is depicted in the curves Fig. 6 to 11. S ince, in

accordance with the foregoing remarks, these are

the sum oftwo curves, they only apply to the r.urrent

at which they were plotted and cannot necessarily

be converted to heavy current loads.

-7-

, ~ ~-. ~~._. p ~..- ~ ..


8/10

If

BROWN, BOVERI CO., LTD., B. .DEN, SWITZERLAND

T' 20 min

T= 30 min

Curves of temperature

of secondary thermal relays type ST

6t

\I/u~t

200i 120

180

uiO

'40

120

u)O

80

60

40

20

0-

,

,/

40

1ft

, '

I

,

20

,

o 20 30 4010

50s

-

')'./

~

'--

--1-- '--

---

---

I

~

-20 mill H~, 5a)

-..

100 min (1-8)

5XT

-

-

- ,-

~

5

10

20

I

60

3

80

4

40

2

197)Z 1

Fig. 6. Time CCinstdnt T-

20 mln

6t' .161'

2001 120r-r- --

180

00

100

80

60

40

20

3

4

(4a. Sa)

min (1-8)

5x':'

'~) I

2

. Fig. 7. Time constantT

- 30min

-8-

'm.-rr

- - -

...---...-

----- - - --

8

- - - ....

1

180

160

140

120

100

80

60

40

20

0-' 0

--

160

100 J //

40

-:/- 80 - -tYi.'

120

1/

I 5a }

I

V

- 100 60 1

3 ,

--

--

'

'

4,,'

--

'

.

I '(

-/

80

,/

'

I

j,

/-

4a J:::

--

60

40

//

,'h

--

,, /

- -)I-- --

40

,

20

\'

'I

I

//

-/

--1

20

/

/

I

-

0- 0

\

1J3;

/.

20

30 40

50s

10

I,

--

/'

/6__

ttW

- -... :z--

--

f-. _

I

J

- -

\ ,

---

---

--

--

-

- -

;

/If,

;(/

3

--

-----

r

-

'

---

,

VI

-

-

--

t

,/

I

I

:2

g

...

%

7

. 1:

- -

-

t

;:--

'-.

-.

--

-

--

,..

- -

-

-

-

--

i

-,

o-..

--

I

--

-

--

--

-

-

-

---

-

-

-.

8

I

--

. --

----

5

10

--

.-

2S

min

5

O.

30

60

90


9/10

.

BROWN, BaVER I &.CO., LTD., BADEN, SWITZERLAND

1

I

rise and decrease

Steady-state r s for set current = 60C

ut OfoT6tOC

2001 120

180

200

'''

+ -r-

I

I 160 100-

~

0 I - - --- 140

/, j

-- r'

80

~ I

4 .' _/~~~-- ----

120

W

if/1;, 3

>:

~

-

t/:

.-'

100 60

I

~'

h-.'

5

-,. --

80

' ,

)() IT. 'a - ,, ., I

~

'''1/ ~'- ,- - 40 ' ,

~

/, v,. -- ,. ~,/ 60 ~'t 1

// /jX

1/'

I / ':7,/ , V/ 4a 40 20 ,

,

, ,

,

.',

I

20

1

~O ' I - .I 1/'/ ,.

'fA

, I ~ .V,' 0 0

f--

'f.,',

.' / -~ ~:_ __ /6

0 10 20 :;0 40 50s

, ,\

:m

~

//

- -,- - -- ---

I ,I / ~

/ -- --- -- ---

)() ,

..

---- --- -

,

I

~

.~

--- ::: :-- --- --- --- -- -~ ---

I I I,

~

,~~

---

') , ,>':': :\,---- --- -- --- -- -- -- --- --- -- ---

l/

i

/

':%~ ::;~::;'-; -- -- ---

~o ,I V. / ''' - ~ ~,-

,I

~

~'

,

~

'.-

I ,, r J , JIll ........

I 1

., .. ....

ri

rJ

' b.? ..~ .. ~~~ /7

. / , ~

~

...

/

,~ 1/' ::-:::;:- -

.I~ ' ~ .~~

--

~O

11/ ~

- :::.

--- -- ---

.',~ :::::s-- --- --- --- --- --

-~ ' ,-- -- - --:- --- -- --- -- --- -- --- --

'/ ' -,.~ ~- ' 8

___~J'- 10

-

-..s; ~ ,

0 30 -

/1

--- -_

50 min

180

160

140

120

100

o

o

80

2

160

4

40

I

120

3

Fig, 8. Time c;onstant T

-

40 mln

Legend:

1 Curve of temperature rise for

0,5

x 'E

2 Curve of temperature rise for 1 x IE

3 Curve of temperature rise for 1,5 x 'E

4 Curve of temperalure rise for 2 x IE

4a Curve of temperature rise for 2 x IE

Sa Curve of temperature 'rise for 3 xJE

6 Cooling c;urve when fed with 1 x IE

7 Cooling c;urve when fed with

0,5

~

'E

8 Cooling c;urve when relay dead

9 Curve of temperature rise for 6 x

IE

The c;oollng c;urves are plotted with an Initial temperature rise

of 100 C (relay with degree sc;ale)

The foUm,lng are plotted:

Ordinates: Temperature rise dt for relays with % sc;ale

Temperalure rise

d

1 C for relays with. C sc;ale

Abc;slssae: Time In mln for c;urves 4a and Sa

Time In mln for the other c;urves

Time as multiple of the time c;onstant T

Mean value

Sc;atter

r=40rnin

(4a, ~'ia)

~

200 min (1-8)

5xT

41I

-9-

~ rI :'

':' ~-. .~~ ,

20

I

0


10/10

--

200

180

160. 100

140


T =

6IJmin

Curves of temperature

of secondary thermal relays type

ST

o

160- 1 9 // ..

~ 140- 80 '') / ...~/

,I' -- - - 12 .// ...'

,Ii' /1 I --t::- _ __ J / /,

4..u1 r'h5 3 ,c ~ - -- 100 60 /

1/7/

/1// a ,,--; ~ ' -- 80 ///1

I

-

~ 'f

~ 'I, // // / ~ /': 60 1: '/

I~, I

/

1/1 ///

___ 4' 1, ~ ,20 h /

~,~ /J /

I/~ ~ ' : ;;:::- -

Iii ..:; .. & --- __ -- L

.. ~- --.

I. .~

'

1

i ~tO::,_ ___ ___ _ - -- .-

'-. i

- - - - ---

__: 10 20 -- ~~;

-- ~ 8

\ 51

80

60

~

2

60

1

110

2

180

3

240

4

o

o

FiO. 9. Time constant

T

-

60 min

-10-

(4a, 5~)

~

300 min (HI)

5x..

MI

----

Documents

CALOR EMAG bag.1.pdf