Westinghouse Db-50 User manual

(

I

:1

I

!

t

I

'

11

i

'1:_/;<:')

(

·v;,;;;/

\,

t1

Instructions

for

Types

DB-50,

DBF-16

and

DBL-50

Air

Circuit

Breakers

Westinghouse

Electric

Corporation

Switchgear Division, East

Pittsburgh,

Pa.

- <

LB.

33-850-3D, Effective May, 1970. Supersedes l.ll. 33-850-3-C, March, 1966.

::.

;;

'••

.,

..

Courtesy of NationalSwitchgear.com

Page 2

-..'

--,

Table

of

Contents

Part

1 -

Receiving,

Handling,

and

Storing

Inspection.

Storing

Part

2 -

Installation

Connections

. . • . . . .

Part

3 -

Maintenance

Pole

Unit . • . . . • , • .

Contacts

. .• . . • . • .

.. ... ... . .... " .. .. " ...... .

Maintenance

of

Contacts

.

Operating

Mechanism

• . . . . . . . . . . • . . .

(Closing

Spring

Mechanism)

Spring

Closing

Assembly

Closing

Solenoid . . • . . , .

Overcurrent

Tripping

Device

Installation

and

Removal

Overtravel

Adjustment

•.

Construction

• . . . . . . •

Time-Current

Classification

Operation . . . . . . . . . .

Time-Current

Characteristics

Adjustment

of

Calibration

Settings

Control

Relay

...•..

, . ,

•.

Shunt

Trip

Attachment

. . • . , . . .

Undervoltage

Trip

Attachment

.•...

Undervoltage

Time

Delay

Attachment

.

Reverse

Current

Trip

Attachment

.

Field

Discharge

Switch . , .

Auxiliary

Switch . . . . . . .

Alarm

Switch

Attachment

..

Electric

Lockout

Attachment

Key

Lock

Attachment

. . • ,

Key

Interlock

Attachment

. . • . ,

..

, • , . , . ,

...

Rectifier

Unit

for

A-c

Undervoltage

and A-c

Electric

Lockout

Attachments

, . , . .

Type

DBL-50

Breaker

• . . . • • . • . • • . . • . . . • . • .

Page

5

6

9

12

14

15

16

21

24

26

27

28

30

32

34

36

C

·.'.>.o,,

,

.....

y

,_

_.,_,:..-

Courtesy of NationalSwitchgear.com

.'.l

•J

List

of

Illustrations

Figure

1

lA

2

3

3A

3B

4

5

6

7

8

9

10

11

12

13

14

15

16

17

18

19

20

21

22

23

24

25

26

Page

Type

DB-50

Fixed

Circuit

Breaker

Outline

Dimensions

and Mounting

Details

. . • • , , . . . . . . . • . , . . 7

Type

DB-50

Three

Position

Drawout

Outline

Dimensions

8

Typical

Wiring

Diagrams

-

Type

DB-50

Fixed

Circuit

Breaker

. . . . . . . . . . . . . . . . . . . . . . . . 10

Cross-Sectional

View of

Type

DB-50

Circuit

Breaker.

11

Type

DB-50

Spring

Closing

Assembly

. , , , , , . . . 12

Type DB-50

Three

Position

Operating

Mechanism.

, , . , 13

Series

Overcurrent

Tripping

Device

with

Long

Delay

and

Instantaneous

Elements,

, , . , , , , , , , , , , . , , , 14

Series

Overcurrent

Tripping

Device

Showing

the

Assembly

of

Calibration

Case

to

Magnetic

Circuit

. . . . . , . . . . 14

Cross-Sectional

View of

Series

Overcurrent

Tripping

Device

with

Long

Delay

and

Instantaneous

Elements

, , , , , , 15

Tripping

Characteristics

of

Standard

Series

Overcurrent

Tripping

Device

with

Long

Delay

and

Instantaneous

Elements

. . . . . . . . . . . . . . . . . . . . . . . . . . . 17

Tripping

Characteristics

of

Selective

Series

Overcurrent

Tripping

Device

with

Long

Delay

and

Short

Delay

Elements

. . . . . . . . . . . . . . . . . . . . . . . . 18

Tripping

Characteristics

of

Special

Series

Overcurrent

Tripping

Device

with

Instantaneous

Element

Only

..

, 19

Schematic

Diagram

of

Standard

Series

Overcurrent

Tripping

Device

with

Adjustable

Long

Delay

and

Adjustable

Instantaneous

Elements.

. . . . . . . . . . . . . . . . . . . 20

Schematic

Diagram

of

Selective

Series

Overcurrent

Tripping

Device

with

Adjustable

Long

Delay

and

Adjustable

Short

Delay

Elements

, , , , . , , , , , . , . . , . , . , . , . . 22

Schematic

Diagram

of

Series

Overcurrent

Tripping

Device

with

Instantaneous

Element

Only , . , 22

Discriminator

for

Tripping

Device

. • , , , , , . . , • , 23

Closing

Solenoid -

Construction

Details

, , , , , , • . . 24

Control

Relay

-

Adjustment

and

Construction

Details

, , 25

Shunt

Trip

Attachment

-

Location

&

Construction

Details

,

26

Undervoltage

Trip

Attachment

-

Construction

Details

, ,

28

Undervoltage

Time

Delay

Attachment

-

Construction

Details

29

Reverse

Current

Trip

Attachment

-

Construction

Details

,

29

Field

Discharge

Switch -

Construction

Details,

, , ,

31

Auxiliary

Switch

-

Construction

Details

, , , . . , , , . .

31

Alarm

Switch

Attachment

-

Construction

Details

, , , , •

32

Electric

Lockout

Attachment

-

Construction

Details,

, , .

33

Key

Lock

or

Key

Interlock

Attachment

for

Fixed

Breakers

-

Construction

Details

. • , , , . . . , , . , . , , , 34

Rectifier

Unit

for

A-c

Electric

Lockout

Attachment

,

35

Type

DBL

Air

Circuit

Breaker

, • , . ,

.•.

, , , .

36

P_age

3

Courtesy of NationalSwitchgear.com

/

Page

4

General

Type "DB"

air

circuit

breaker

is

designed

to

give continuous and

reliable

service

as

the

protective

linkbetween

the

power

source

,.

and

associated

productive

equipment.

This

breaker

is

built

to

operate

with a

minimum

of

maintenance,

while

at

the

same

time

its

simplified

construction

permits

maximum

accessibility

for

inspection

and

adjustment

when

required.

The

ease

with which

at-

tachments

may

be

added

or

removed

is

an

outstanding

feature

of the "DB" design.

For

the

greatest

measure

of

safety

to

operating

personnel

and

also

to

minimize

maintenance

requirements,

the

breaker

should

be

mounted

in

an

enclosure

suitable

to local

operating

conditions. A

selection

of

standard

enclosures

is

available

for

various

applications,

IMPORTANT:

To

assure

proper functioning,

inspect

each

breaker

at

regular

intervals

in

ac-

cordance with a

systematic

maintenance

schedule.

The frequency and

character

of the

inspections

will for the most part be deterinined

by

these-

verity of the duty performed. The minimum re-

quirements, however, should

consist

of a light

monthly

inspection,

with a thorough inspection

semi-annually. Occasional

checks

on

calibra-

tion

as

well

as

on

coordination and freedom of

all moving

parts,

must be included

in

the mainte-

nance sc.hedule. Consult Westinghouse engineer-

ing and

service

personnel for recommendations

pertaining

to

special

operating

or

maintenance

conditions.

•

Courtesy of NationalSwitchgear.com

Page

5

PART 1 -

RECEIVING,

HANDLING,

AND

STORING

Type

"DB-50"

air

circuit

breakers,

with

all

attachments

mounted

in

place,

are

shipped

in

special

cartons.

Important:

To

avoid

damage

to

the

breakers,

do not

use

hooks in

handling.

Net

weights

of

Type

DB-50

are

given

in

Table

No. 1

below.

TABLE

NO. 1 -

Type

DB-50

MANUAL

ELECTRIC

2-Pole

220 1

bs.

295 1

bs.

3-Pole

280

lbs.

355 1

bs.

Add

30

Lbs.

for

Drawout

Details.

Add

~5

Lbs.

for

DSL

Oeta i 1

s.

Immediately

upon

receipt,

examine

ship-

ment

for

any

loss

or

damage

incurred

during

transit.

If

injury

or

rough

handling

is

evi-

dent,

file a

damage

claim

at

once

with

the

transportation

company

and notify

the

nearest

Westinghouse

Sales

Office.

When

unpacking,

be

sure

that

no

loose

parts

are

missing

or

left

in

the

packing

material.

Heport

all

shortages

at

once.

Blow

out

any

dust

or

particles

of

packing

material

that

may

have

accumulated

on

the

circuit

breaker

parts.

Do not

remove

tape

from

top

of

arc

chutes

until

breaker

is

to

be

placed

in

service.

INSPECTION

The

"DB"

breaker

assembly

consists

of a

coordinated

group

of

sub-assemblies

mounted

on a

steel

supporting

panel.

The

complete

breaker

assembly

is

to

be

mounted

with

the

steel

panel

in

a

vertical

position,

All

inspections

for

proper

operation

should,

therefore,

be

made

with

the

breaker

in

this

position.

Final

inspection

should

preferably

be

made

with

the

breaker

in

its

permanent

mounting.

Inspect

the

breaker

as

follows:

1.

Haise

and

lower

the

trip

bar

by

hand

to

make

sure

that

it

does

not

bind.

2.

Hotate

the

manual

operating

handle

slowly

in

a

clockwise

direction

to

move

the

contacts

toward

the

closed

position,

a,

Observe

whether

all

parts

are

in

proper

alignment

and

move

freely.

b.

Make

certain

that

the

studs

have

not

been

forced

out

of

alignment.

c.

Be

sure

that

the

contacts

are

clean

and

properly

aligned.

For

a

description

of

contact

alignment,

refer

to

"Contacts",

Page

9.

3.

If

the

contacts

are

in

alignment

and

all

parts

move

freely,

continue

the

clockwise

rotation

until

the

breaker

is

latched,

4.

Push

the

push-to-trip

button

to

trip

the

breaker.

a.

The

toggle

linkage

should

collapse

and

the

moving

contact

assembly

move

freely

to

the

full open

position.

This

should

be

followed

immediately

by

complete

re-

setting

of

the

links

in

the

toggle

mechanism.

b.

The

links

must

always

be

free

to

move

without

friction

or

binding.

5.

Check

the

attachments

for

opeTation

in

accordance.with

the

appropriate

instructions

·

as

given

under

"Maintenance",

Part

3

of

this

book.

NOTE:

It

is

not advisable

to

lubricate any parts

of the breaker. The lubrication supplied during

factory assembly is sufficient

for

years of serv-

ice. The lubricant is of a special

form

which is

used sparingly. The addition of oil will only

pro-

mote the accumulation of dust and dirt.

STOHING

If

circuit

breakers

are

not

to

be

installed

in

their

permanent

location

at

once,

they

should

be

carefully

inspected

for

loose

or

damaged

parts·

and

then

stored

in

a

clean

dry

place

in

an

upright

position

to

avoid

damage

to

the

circuit

breaker

parts.

A

covering

of

paper

will

prevent

dust

from

settling

on

the

circuit

breaker

parts

and

is

preferred

to

packing

or

other

materials

that

are

apt

to

absorb

moisture.

Hemove

the

tape

from

the

top of

the

arc

chutes

be-

·

fore

placing

in

service,

Courtesy of NationalSwitchgear.com

Page

6

PART 2 -

INSTALLATION

Type "DB-50"

circuit

breakers

are

fur-

nished

as

complete

unit

assemblies

and

the

installation

consists

of: (1)

bolting

them

to

the

supporting

framework

or

structure;

(2)

connecting

the

current-carrying

cables

or

bus

bars;

and

(3)

completing

any

secondary

control

wiring

that

may

be

necessary.

CAUTION: During

installation,

the

circuit

breaker

should

be

in

the

open

position.

Be

sure

to de-

energi

ze

the

load and control

leads

to be con-

nected,.

and

also

the

section

of the

switchboard

where

installation

is

being made.

Mounting

dimensions

and

details

of

the

front

enclosure

cutouts

are

shown

in

Fig.

1.

To

prevent

distortion

of

the

breaker

panel,

the

supporting

structure

should

be

checked

for

alignment.

CONNECTION~

Typical

circuit

breaker

w1rmg

diagrams

are

shown

in

Fig.

2.

The

connecting

cables

or

bus

bars

should

have

adequate

current-

carrying

capacity,

otherwise,

heat

will

be

conducted

to

the

circuit

breaker

resulting

in

possible

excessive

temperature

rise.

Connecting

cables

or

bus

bars

must

be

supported

so

that

the

circuit

breaker

studs

will

not

be

subjected

to

unnecessary

stresses.

The

circuit

breaker

studs

and

all

con-

nections

should

be

clean,

smooth,

and

free

from

burrs

to

assure

full

contact

area.

They

should

be

firmly

clamped

or

bolted

in

place

to

prevent

excessive

heating.

TABLE

NO. 2

Closing Solenoid Control Voltages, Tripping Currents, Closing Currents and Fuse Ratings

CLOSING

NOMINAL

RECOMMENDED CLOSING

COIL CONTROL CLOSING TRIPPING

FUSE

AMPERE RATING

FUSE

BURDEN VOLTAGE AMPERES AMPERES STANDARD

NEC

STYLE NUMBER

250

VOLT

600

VOLT

24

DC

---

9.5

48

DC

---

5.0

125

DC

18 2.0

10

120A823H04

250

DC

8 1.0 6 120A823H03

•·sTD. 230 AC 10

.5

6 120A823H03

460AC

5

.2

120A824H01

575 AC 4

.3

3 120A824H01

115 AC

20

1.

10

120A823H04

*

For

A-C

closing

use

3

KVA

source or

larger.

Supplied for

breakers

having

dual

overcurrent

tripping

devices

(Long

Delay

..

Instantaneous

Type)

or for

breakers

having

dual

selective

overcurrent

tripping

devices

(Long

Deloy

..

Short

Deloy

Type)

plus

discriminator

details.

Courtesy of NationalSwitchgear.com

-:!

•J

rr

Ii

I

CURRENT

STUD ARRANGEMENTS

'-''-~~z:,_,:_____.

,/'.)\

(FRONT

VlEW)

1':

"t

1~+

+

+11

I~

I +

+11

U+

±1ll*

"±

$IJ

"t

FIG.

I -

-·-

-

FIG.4

FlG.

.:.

FlG..3

1.

POLE

5REAKER

<.

?OLE

BREAKER

WlTll

~,._._...,

J

..

n~CK!>.;::G..E

CONTAC."TS 2

POLE

BREAKER

WnK

R<:n:l':'>E.

CURR,ENT ATTACll,...'EITT

(&TD.

NE.MA

ARRA

..

G.E.ME

..

T)

\;_~,~':~:',.,~::'::Pus"-'"'

UVE

PAA:fS

oR

C.OMSIJSTIBLE

MATERl/l\L

____

\

A'<U\LLY4.~~E.

_____-cf'IUST

NOT

SE

UXATE'P

IN

TIU5

AP:.£1>.,

~-I

-I

--

\ ,

~

(UNl-E~

G.l>.S

DE~LE.C.TING,

BARRIERS

4 ,

g-----j

\181

A.RE.

-OV!l:>El>

A'f>

INDICATED.

'2-

POLE

BREAKER

WI l

><

REl=t:

CURR"E!llT A"TTACH!loiENT

(STI>.

Fl~-AIE:E.

MP.Rl

..

E

~fo\E!>.lT)

STEEL

SAS.E.

llk,='>.Of'WlNG,

K£Y

""1'ERL~R

l<£Y

l.JX.l<~

r

;;~EQ.

·+rjr·11

""

f

Lfr

I

FIG..«>

Cl.ITOUT

IN

DEAD

FRONT

DOOR

OR

COVER

(SUPPLIED

BYSWITCH60ARD

BIJ!L.Dra)

l.--i,O~Gt--1

r----1'2.APP~~-----f

___j___'

__

,

__

-=--i___

-

f===-_______:__·r---=--,._I

.,.,

•

re=

' . '

I'

AR!:"-

CRISfE I

ch

:

$.-<>•~.(?_)

I

NOTE:-

WHEN

PUSH

TO

TRIP

ME.WIAN;,._..,.

IS

5UPPL!l!.D

,BREAK.r.R

......_...,

E>I!

l..OCK£P

!N

"fR;\?

i'Rr.E.

CONOITIO>l.

~

PA.OLOCK.!!>

AT

TR1?

&\ITTC»i.MANOL'E.

0$1!.C

ONLY

FOR

-C::LOSlNC.

ASSl-lCIWH

<.~

_

\OCLOSE..

ih j' ' I I

~I

I l

<'ll...

L_

i

<r:

' l /

\<)

Ro"<"F>0<Y"'-'"' I J

~

,,.

.,

.. . -I

_,._

-

~~...

i

-=-----

0

MOU>mNG.

HC>!..£5

j

~~lrt"?RlPPP>

I

11·

T

ii

I~

'

~~~F<>f!>!IZ«E?>

I

.I

Q '

!'"AC.I.

PLK!'E----- I I ! I

Ii

-~

' I I

J;J

' i

1-1

J.

I , : i I

IJ

,_~31·

IW

'I

m~

I

::

1

,,

. ' I

P'CS\T\ON

lt!DICll.TOR

' I

".

i I m

,.+,,t

~

ro

I

'

Ji

'~

,,

11

!·

I j l

!1

I

!I

I

~

J

.

I

'

"

3..,_T>1A

('t.}

\ff""~

RO"fAR

.....

TO'tU'"Ml!.C\.IANl$M

It,

$.)"9l_!l:.0.,eR~AKE.R

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

R>1i

I.QC"""'<>

JJL

'·11L..i.

-1---i-

IN

TR\P..,RE&

CONOtT\ON

........

P....:...""""""

O"l

H,.,NOL

...

AT

TRIP

POl>IT\0~.

--"!'-,

Too..o~~TIU?

"l

-<

-n<g l"OU,..OWING,

}..TTACHl'<Ell"l"S

CAM

61<:

=P?LI"U>!

Wln.<>UT

!~~\~

OVERAW...

»>ME.N.sio.;.$-1

AIJJ..lL\11.R'f 'l>W!TCHES.

(8

C...\..,CUIT

MAXlMUl'\)j

~~~,!;E.

TklP(WITllORW!TllOVT

11ME.

WAY;

ALARM

S.WlTCK

K'E.Y

l..OC.K

OR

KEY

lNTE.RL.OCK

FIE.L"D "Dls.<:.MAR<O,E C.Or.tTAc:r

E.LE.C.TRIC.

1..0CK.OUT

OPERA"TlON

c.CUNTE.R

OVD!CIJRJU:NT----------

T~P

~/

ILTJ

~

!~L'"-""-"7

,,

""

,

• l5u;_"'1>l

••

-

-~----~

80<.>"'PARY

:><.>!?,.-AC<:'>

OV

OltE'.

"-tF«:.UIT

SREA!<E:R

"-''""

"'»:>

~

c.o>.!SlDE:

...

&O> <OR<>Vi-a>

F'OT~TJAL.

~YE.R$E.

CURR:E:NT

TRIP

f.-----19~'.:f;..----------

"=

CENTER

Fill£

srul?S(Slt>E'lll!l()I

:,.~<rn;~)

~~t;~s~,;w~-._,';o'f

..

~~

Fig. 1 -

Type

DB-50

Fixed

Circuit

Breaker

Outline

Dimensions

and

Mounting

Details

·-·~

;,,,_

"

-·

\

.. ' '

'.-i

'~)

>-j

~

m

~

,,,_,_-,,.,-·..,-~

Courtesy of NationalSwitchgear.com

~

.;;

t

..,.

UPPER

FOR

3 Y T

'sruos

POLE

BKR.

~

t

BKR~

'_

LOWER

~

3

l

STUDS

lliLl

f"RONT

VIEW

OF

STUD

LOCATIONS

FOR

MOUNTING

3

POLE

BREAKER

WITH

2

OR

3

OVERCURRENT

TRIPS

OR

2

POLE

BREAKER

WITHOUT

REVERSE

CURRENT

TRIP

+ I

c-P

.

•.

I

~BKR

'

i"'P+

FIG

2

NEMA

STD.

FRONT

VIEW

OF

STUD

LOCATIONS

FOR

MOUNTING

2

POLE

BREAKER

WITH

2

OVERCURRENT

TRIPS

AND

REVERSE

CURRENT

TRIP:

~:

~

·~·

-i2~f-

s

L..J

4 '

_ru;__,i_

CUTOUT

IN

DOOR

"

19~----.

i-1---~9;;~-6

--

6---\

OMITTED

ON

2

POLE

BKR.

POSITION

_

1NDICATOR

ADDITIONAL

4

POJNT

AUX.

SW.

4

POINT

AUX.

SW.

~

N

~'"

~

DJSCONN.

POS.

TEST

"10S.

CONN

POS.

MOVABLE

ESCUTCHEON

PLATE

MIN

POSITION

Of~

TC(

INTERLOCK

' I l

i--6::;:1

-$-

THE

FOLLOWING

ATTACHMENTS

CAN

BE

SUPPi.JED

Wl1HOUT

INCREASING

OVERALL

DIMENSIONS:

1-AUXILIARY

SWITCHES

02

CIRCUIT

MAX.)

2.

SHUNT

TRIP

3-UNDERVOLTAGE

TRIP

(WITH

OR

W/TflOUT

TIM£

DELAY]

4.ALARM

SWITCH

5

ELECTRIC

LOCKOUT

6.0PERATION

COUNTER

B

6FINGERS

f

f!

--

~

-~

'

__

12

OR

24

SECONDARY

.

EL

BASE/

SUPPLIED.

LOWER

12

CONTACTS

CAN

BE

CAN

BE

OMITTED

~··

~

I

*

tSECONDARY

I

CONTACTS

"

UPPER

l

STUDS

,,HANDLE

I

'

i~1·

'

~""

,,

, 1 I 11 ISHUt-}T

11

l,}~..31r;::~:1

m

INTERLOCK

HAND

TRIP

AND

PROVISON

FOR

PADLOCKING

'i""l

I J--1--c I

BKR

JN

TB!PPED

-11

t '

(I

I

:1

POS!TIClt\t.

PAD-

LOCK

FURNISH-

ED

BY

CUSTOM-

ER.

CONTROL

RELAY1

~:cuRRENT_,,j

I

[I-+

kkd

f!]~

2

FOR

2

POLE

Il

20~~

.

REVERSE

CURRENT

TRIP

J.i

r1?-----i

I~

I - r

3

FOR

3

POLE

"'

28

~~-"'~'~~~-'-~~~~~

Fig.

IA

-

Type

DB-50 Three

Position

Drawout

Outline

Dimensions

POSITION

'GROUND

FINGER

CONTACTS

I

-;l._~

">

~

ro

00

/C-:-\

cz;i

Courtesy of NationalSwitchgear.com

,

..

Page

9

PART

3 - MAINTENANCE

POLE

UNIT

Each

pole

unit

is

mounted

on a

separate

molded

base

through

which

the

breaker

studs

pass.

(See

Fig.

3,)

The

molded

bases

are

attached

to

the

steel

mounting

panel

and

provide

insulation

for

the

breaker

studs.

The

upper

stud

and

contact

are

attached

to

the

molded

base

by

two

bolts,

The

moving

contact

is

pivoted

on

the

molded

base

and

attached

to

the

cross

bar

through

insulating

links.

The

series

coil

and

lower

stud

are

fastened

to

the

molded

base

by

four

bolts.

Contacts.

(See

Fig.

3,)

The DB-50 arcing contact should touch first on

closing, open last on opening. Contact pressure on

the mains

is

maintained by adjusting gap G

to

be

.050-.093 inches. This

gap

is

adjusted by

removing the cross bar and screwing the insulating

link in or

out

on the stud.

Be

sure to tighten the

lock nuts after each adjustment.

Do not

over-adjust

as

this

will

cause

the

contact

springs

to

compress

to

the

solid

position

and

thus

increase

the

closing

effort.

Check

for

over-adjustment

by

prying

the

stationary

arc

tips

open

to

at

least

1/16-inch

gap.

Maintenance

of

Contacts.

Rough

or

high

spots

should

be

removed

with

a

file

or

sandpaper.

To

replace

the

arcing

contacts,

open

the

breaker,

remove

the

arc

chutes

and

then

the

stationary

arc-

ing

contacts.

Close

the

breaker

and

remove

the

moving

arcing

contacts.

The

new

con-

tacts

can

then

be

added

in

the

reverse

order.

CAUTION:

All

power should

be

removed when

changing,

maintaining

or

adjusting

contacts.

OPERA

TING MECHANISM

The

operating

mechanism

(see

Fig.

3)

is

non-adjustable

and

consists

of a

series

of

non-ferrous

links

designed

to

secure

low

closing

and

tripping

forces.

To

check

for

friction,

raise

the

trip

bar

and

slowly

rotate

the

manual

operating

handle

in

close

di-

rection.

The

linkage

should

follow

the

handle

without

sticking.

A

small

quantity

of

lubricant

is

placed

on

the

handle

shaft,

the

roller

lever

roller,

and

the

latch

plate

at

the

factory.

CLOSING SPRING ASSEMBLY

The

closing

spring

assembly

is

shown

in

Fig,

3A.

Rotating

the

closing

handle

clockwise

raises

the

lift

link

and

lower

spring

guide

to

compl'ess

the

closing

spring.

Near

the

end

of

the

closing

stroke

the

top

end

of

the

lift

link

strikes

the

first

toggle

lever

to

start

the

breaker

closing.

As

the

breaker

closes,

the

push

rod

raises

the

toggle

link

and

push

link out of

the

toggle

which

permits

the

closing

spring

to

complete

the

breaker

closing.

Slow

emergency

operation

to

check

the

contact

sequence

can

be

obtained

by

exerting

a

slight

closing

pressure

on

the

closing

handle

and

simultaneously

pushing

forward

on

the

breaker

cross

bar

to

start

the

breaker

closing.

Maintenance

Oil

the

pins

and

slides

every

10,000 op-

erations.

CLOSING SOLENOID

The

closing

solenoid

(see

Fig.

14)

is

non-

adjustable.

It

is

designed

for

intermittent

duty only.

Check

for

loose

bolts.

To

remove

closing

coil,

trip

breaker.

Disconnect

closing

coil

leads

from

control

circuit

wiring.

Take

off

bolts

(9),

washers'

(12),

relay

release

arm

(8),

bolts

(10),

washers

(11) and

plate

(2).

Drop

closing

coil

(7)

with

brass

tube

(5).

Courtesy of NationalSwitchgear.com

I

I/

'

Page

10

l~--------

Courtesy of NationalSwitchgear.com

'j'

1

"

.L

·'i

,

.......

,.

'\

~

:/

DB-50

CIRCUIT

BREAKER

1600

AMPERES.

600

VOLTS

A-C

PUSH

TRIP

317

\

HANDLE

316

MOVING

ARCING

CONTACT

301

MECHANISM

302

CLOSING

SOLENOID

303

STEEL

PANEL

315

ARC

CHUTE

300

STATIONARY

ARCING

CONTACT

314

UPPER

STUD

313

' '

MAIN

MOVING

CONTACT

312

G(.050-.093~)

---AUXILIARY

1J~f;:I

MAIN

I

CONTACT

LOWER

COIL

TERMINAL

306

OVERGURRENT

TRIPPING

DEVICE

305

310

"MOVING

CONTACT

HINGE

309

A

LOWER

STUD

307

UPPER

COIL

TERMINAL

308

~~

~

~·

~

_fl~

_

_..,,~'---

CLOSED

TRIPPED

OPEN(RESET)

u

Fig. 3 -Cross-Sectional View

of

Type DB-50 Circuit Breaker

Page

lJ

Courtesy of NationalSwitchgear.com

I

Pa_ge

12

In

replacing

closing

coil

be

sure

to

re-

place

brass

tube

(5)

so

that

stationary

core

(4) and

moving

core

(3)

are

aligned

in

the

tube.

Re-assemble

closing

coil

and

details

in

reverse

order

from

removal.

If

the

circuit

breaker

is

permanently

mounted

near

the

floor

so

that

the

closing

coil

cannot

be

dropped

far

enough

for

re-

moval

then

follow

these

directions.

Trip

breaker

and

remove

breaker

manual

op-

erating

handle

and

breaker

face

plate.

Dis-

connect

closing

coil

leads

from

control

cir-

cuit

wiring.

Take

off

bolts

(9),

washers

(12),

relay

release

arm

(8),

bolts

(10),

washers

(11) and

plate

(2).

Drop

closing

coil

(7)

with

brass

tube

(5)

so

that

(6)

is

exposed.

Push

(6)

to

right

into

hole

on

right

hand

side

of

solenoid

yoke (1) and

allow

moving

core

(3)

to

drop

into

brass

tube

(5),

Pick

up

closing

coil

with

brass

tube

and

moving

core

and

bring

out

through

the

U-shaped

foot on

breaker.

Re-assemble

closing

coil

and

details

in

reverse

order

from

removal.

Take

care

to

align

stationary

core

(4) andmoving

core

(3) in

brass

tube

(5).

OVERCURRENT

TRIPPING

DEVICE

The

overcurrent

trip

is

an

air

delayed

device

that

can

be

supplied

with

various

rating

coils

ranging

from

200

to

1600

am-

peres.

The

construction,

except

for

the

coils,

is

similar

for

all

ratings.

ROLLER

LEVER

l'IRST TOGGLE LEVER

MECHANISM

•r

----

:

I'

HANDLE

PUSH

TRIP

LIFT LINK-111;1--I

TOGGLE

UNK-

-

PUSH

LINK-

UPPER

SPRING

GUIDE

LOWER SPRING GUIDE

SPRING MECHANISM

DB-50

CIRCUIT

BREAKER

1600

AMPERES,

600

VOLTS

A-C

Fig. 3A -Type Dll-50 Spring Closing

Assembly

BA!i

TRIP

BAR

LATCH

PLATE

Courtesy of NationalSwitchgear.com

-_,

""

·~'

I

ol'!IJ

,:;,

f

MECHANISM EXTENSION

~·-CHEOO

, I

'tFRONT

VIEW:

· FACE-f'LATE,HANO..£

l a PANTOGRAPH

uNKS

INOT,..OWN

I

·"."!'"',;.,;,=.,._.··

'':}

TEST

POSITION

MARK

MANUAL

TRIP

PRESS

LATCH

TO

REMOVE HANDLE

Ai

J

Fig.

3B

-

Type

DB-50

Three

Posit1.on-eff8rating Mechanism

"'.l·

~

"'

>

~

0

~

·

..

:.,

Courtesy of NationalSwitchgear.com

Page

14

Fig. 4 -Series Overcur-

rent:

Tripping

Device

with

Long Time and Instan-

taneous Element

peres.

The

construction,

except

for

the

coils,

is

similar

for

all

ratings.

The

overcurrent

tripping

device

can

easily

be

removed

from

the

breaker

and

replaced

with

another

unit of

different

rating

or

of

the

same

rating

without affecting the

calibrations,

Installation

and Removal

CAUTION: Before removing

or

installing a trip-

ping device, be sure that the breaker is

in

the

open position and de-energized.

To

remove

an

overcurrent tripping device

from

the breaker, re-

move

the four bolts A Figure 3 which hold the

tripping device

to

the breaker base. Before re-

moving the

last

bolt, hold the tripping device

to

prevent it

from

falling.

To

install

the

overcurrent

trip

to

the

circuit

breaker

it

is

merely

necessary

to

insert

the

device

into

the

pole unit

so

that

the

upper

coil

terminal

makes

contact

with

the

lower

part

of

the

moving

contact

hinge

and

the

lower

coil

terminal

contacts

the

lower

breaker

stud

as

shown

in

Fig.

3. The

unit

is

then

bolted

in

this

position

by

means

of

four

hexagon

head,

steel

bolts

2-1

/2

inches

long shown

at

A,

Fig.

3.

Use only one lock

washer

under

the

head

of

each

of

the

bolts.

Care

should

be

taken

to make

sure

that

bolts

A

B

Fig. 5 -Series Overcurrent

Tripping Device Showing the

Assemh

ly

of

Calibration

Case

to Magnetic Circuit.

longer

than

specified

above

are

not

used,

because

the

ends of

the

bolts

may bottom in

coil

terminal

thereby

causing

a loose con-

nection.

OVERTRAVEL ADJUSTMENT

CAUTION:

Do

not attempt

to

check overtravel

adjustment until the breaker has been completely

disconnected

from

any normal voltage source.

The trip screw mounted

on

the trip finger

above the overcurrent tripping device should

be

adjusted

to

gel the same amount of overtravel

that occurred

when

the tripping device was cal-

ibrated for time delay.

If

a tripping device

is

re-

moved

for

any reason, and reinstalled

on

the

breaker, the overtravel adjustment should

be

re-

checked.

When

a new tripping device

is

installed

the overtravel must

be

adjusted.

To

manually

check

the

overtravel

refer

to

Fig.

6. The

air

delay

device

can

be

made

inoperative

by opening the

instantaneous

valve

(or

the

short

delay

valve in

the

case

of

selective

type

tripping

devices).

The

valve

is

opened

by

lifting the

instantaneous

(or

short

delay)

armature.

A

slot

is

pro-

vided in the

side

of

the

molded

case

and a

small

rod

approximately

1/16

diameter

can

be

entered

through the

side

of the

case

and

used

as

a

lever

to

lift

the

armature.

After

the

valve

is

blocked open, the

trip

plunger

Courtesy of NationalSwitchgear.com

..

l>ISCR/N.V;/rM

lli!Mllrv'Ot:

5'

l

-<o••

"''""''"

l

···~

lW"'''"'''

!t==J'~''''""'

"CCP~ND

,.,,D~

~·ew

o~'51lU~\5(LliiT

Page

15

-~~·--

w:u~:~

54

"""'~

""t:t.:""A<J'

" .

~·?

IZ

(~'i,~~i;!Ku•l

\Lo"H'<!l~~~...,,_N,ooo)

~.2'..'.1.!!:'..'!.

~~

Fig. 6 -Cross-Sectional View of Series Overcurrent Tripping

Device

with Long

Delay

and Instantaneous Elements

can

readily

be

moved

upward

to

check

the

tripping

action.

The

trip·

plunger

extends

out

the

top of

the

tripping

device

and

has

a

neck

and

head

under

which

a

forked

tool

can

be

engaged

to

lift

the

trip

plunger

against

the

trip

screw.

Close

the

breaker

and

move

the

trip

plunger

upward

being

careful

to

keep

hands

and

face

clear

of

parts

which

move

when

the

breaker

trips.

Adjust

the

trip

screw

until

the

trip

plunger

moves

it

just

far

enough

to

trip

the

breaker.

Repeated

trials

may

be

necessary.

Trip

and

close

the

breaker

before

each

trial

so

that

normal

latch

lap

will

always

be

used,

When

ad-

justment,

which

gives

just

enough

travel

of

the

trip

bar

to

trip

the

breaker,

has

been

found, add

the

standard

overtravel

which

is

one-half

turn

of

the

trip

screw

downward.

Construction

The

overcurrent

tripping

device

is

air

de-

layed

with

all

of

its

elements

completely

adjustable.

A

typical

unit

is

shown

ready

for

mounting

on a

circuit

breaker

pole

unit

in

Figure

4.

The

tripping

device

consists

oftwo

main

subassemblies

namely:

1.

The

magnetic

frame

and

coil

assembly

as

shown

in

Figure

5A.

2.

The

delay

elements

assembly

as

shown

in

Figure

5B.

The

two

assemblies

are

held

together

by

means

of

the

two

white

mounting

screws

as

seen

from'

the

bottom

of

the

cali-

bration

case,

As

seen

from

the

sectional

view

Figure

6,

the

magnet

frame

and

coil

assembly

consists

of a yoke, a

coil,

a

stationary

and

moving

core

together

with

their

necessary

insulation.

The

delay

elements

assembly

as

seen

from

the

same

figure

contains

an

air

cham-

ber,

a

diaphragm,

and

trip

plunger

as

well

as

all

the

armatures,

springs,

and

valves

to

produce

the

adjustable

long

delay,

short

delay

and

instantaneous

characteristics

bf

the

circuit

breaker

tripping

curve.

Courtesy of NationalSwitchgear.com

j

I

:I

I

,,

Pago

16

Time-Current

Classification

The

overcurrent

tripping

devices

can

be

supplied

with

any

combination

of

the

three

tripping

elements,

namely,

long

delay,

short

delay,

and

instantaneous

elements.

The

most

popular

combinations

are

listed

below:

1. Dual

Overcurrent

Series

Tripping

Device

This

unit

has

an

adjustable

long

delay

and

an

adjustable

instantaneous

element,

the

characteristic

curve

of

which

is

shown

in

Figure

7.

The

calibration

for

the

various

elements

are:

(a) Long

delay

pick-up

Adjustable

with

calibrated

marks

at

80-

100-120-140 and 160

percent

of

coil

rat-

ing,

(b)

Long

delay

Adjustable

with

two

calibrated

marks

at

30 and 20

seconds.

Calibrated

marks

at

20 and

12

seconds

or

at

60 and 40

seconds

may

be

supplied

for

special

applications.

(c)

Instantaneous

pick-up

Adjustable

with

two

calibrated

marks

at

800-1200

percent

or

500-1000

percent.

2.

Dual

Selective

Overcurrent

Series

Tripping

Device

For

Group

or

Tie

Breakers

A

selective

device

is

equipped

with

an

adjustable

long

delay

and

an

adjustable

short

delay

element.

These

two

elements

com-,

bine

to

give

a

typical

selective

curve

as

shown

in

Figure

8.

This

unit

can

be

made

selective

with

a

standard

device

or

another

selective

device

of

the

same

or

of a dif-

ferent

rating.

The

calibration

for

the

various

elements

are:

(a) Long

delay

pick-up

Adjustable

with

calibrated

marks

at

80-

100-120-140 and 160

percent

of

coil

rat-

ing.

(b) Long

delay

Adjustable

with

two

calibrated

marks

at

30

and 20

seconds,

Calibrated

marks

at

20 and 12

seconds

or

at

60

and40

seconds

may

be

supplied

for

special

applications.

(c)

Short

delay

pick-up

Adjustable

with

calibrated

marks

at

500-

750 and 1000

percent

of

coil

rating.

(d)

Short

delay

Adjustable

with

calibrated

marks

at

6-

14 and 30

cycles.

3,

Instantaneous

Trip

Only

This

device

is

equipped

with

an

adjustable

instantaneous

element

only. A

typical

time-

current

characteristic

for

such

a

device

is

shown

in

Figure

9.

This

device

is

available

with

an

in-

stantaneous

pick-up

which

is

adjustable

and

has

calibrated

marks

at

80-100-120-140

and

160

percent

of

coil

rating.

OPERATION

l,

Dual

Overcurrent

Series

Tripping

Device

An

overload

or

short

circuit

through

the

series

coil

D,

Fig.

10, will

cause

the

moving

core

C

to

be

attracted

and

move

toward

the

stationary

core

B.

At low

cur-

rents,

the

moving

core

C

will

carry

the

tripping

stem

F

along

with

it,

and

the

motion

will

be

retarded

by

the

diaphragm

E,

The

rate

of

travel

of

the

diaphragm

is

determined

by

the

rate

at

which

air

is

permitted

to

enter

Courtesy of NationalSwitchgear.com

I

,,

'

,.,

'!

' '

'.l

i

.,:··

"

I

.,

.)

•

]

0

~

-~

•

E

:;:

Page

17

current in percent

of

break~r

trip

ung

rotigq 0 g g gg

88

~ ~

§ § §§

§§§

5 6

769IO

20

30

40

50

fbRg~~

~ ~

§ g

ggg§8

2

~

2

gggg~

"'------.---!:f.

.,. 2

flgggglOOO

'!~~

==:__

-----

--=~~·~-ffa

..

~-

~~!

·!-

~f~~~::j~--l~J;m~~

i~~

-=-

-~~

-

-=--==

:gg

:::

'=_,,

___

:-::,::======:==~j---1-t-1t~

1

H1~;_x'.l·~

';--'\

\j't=t:::!=

]=:

~-__J=i

__

=--f-~-~-+---+---+-1-+_+_-

-_

---+·~

__

,::::::+~-+----+--+-_,·_,·_,-

:~~

()

1 long deloy pickup settings -adjustable with

soo -

--

.

-1----1---1--1--~

v"l

calibrated

marks at

80

1

100,120,140

1

and

---+--+-----~~r-

-

~00

~)(

160 percent

of

trip

unit rating

200•-r

, - c·--- --

~

~==~-::~~IJ==l=tt::~1~=1-I-+---+--+-+-+

---

200

100

~:Jr

____________

--

·-:=

__

J_]\~~X$~~~'~,i~~~$a~t~ot~a~\~~~~~o/.~~~

1

;r~~c~:~~~f=·}~~~~d~3r0

second

long

delay

settings

-

___

j

__

~o

~g.

resettable

delay®~~

-i-----.-f

"'-

1;=

~100°/o

pickup

and

20

seco.

n.

d

tong

delay

settings.--=!-:::[~,_-··-·

eo

101---r--- A 160°/

0 pickup

and

30

second

long

delay

settings

--

-L

1

-

70

60

1

_1

_.

100°/o pickup

and

30

second~.

• -..r

J\

1·~

3lff

60

long

delay

settings

yx \ /

IR

I I 1

1---

so

i----·

100°/

0 pickup and

20

second \

\"\l.X

V\..

.>-i

-" -

"·-

I

50

40

-·-

-

loni

delay

settings

--

·

·--

~---

+----

_j_

40

80

Yo

pickup and 20 second

__

\'"

v / ~'

,,..-lono

del·ay

setting

~adjustable

with

I·

30

\.\-,

IX / /

t.1

r

)I

'".¥

calibrated

marks

at

30

and

20

seconds

\_\...v-~A-"".ioi::

/

V.

'"-~

I'/

"''""

x

><1'.:

,~

v /

1

~

==---=-=

trip

unit

rating (amps)

~~~~',S~~~l'~.L~~l~t~lj~•j~

;

==::.-_:=

1500 soo®

300@

1

_,./ 1 I

1,~=r~j.---=I

-~

-

=-

1- ;, •

6--

-1200

500©

250~

~-+-,

"O

5-

--

-

lOOO

400®

225

3

+-+-1~Nk-l"l-,'llc.7'

//'71--1

_""-=="

instantaneous pickup

setting

#od1ustobte 5 g

4

-··-··-··-

800

350

@

200

3

__.

_______

--

_ with calibrated marks ot

800

and 1200 4

~

""

~

/ percent

of

trip

unit rotino

111

3----

2

---

--

I

·-··--·--

.9--

t-

.9

-------

-

.7----t-

,6---"

.5--

-

.4---.

,3------

.2--

f-

notes:

-r---r-r--r-·l-tl-1'"11T7f'--l--+--i--c-i-

_

-·--·--+--+-r-~<-

__

3

.E

CD

Tota! clearing time

is

the duration of

""

1

~

fault current flow, including arcing

-.--1-+-+-+-l-'l-l-1"1'71f----t--+-+-

·---

--

-r--·--t---i--1-1-r+-1-

2 :;:

time.

r'--"

f/

-f---j--J-t-+-J~,'!"flf'li-!~,'f--4--f---+--j--j-"-H-lf-----j---j--f--+-t-·-I-

,1

/

a

11

owoble

du

rotion of current tlow

=-~·-=l=f=East'Jl~;!===E==J====ES=f-·f-i===-=-E-=::··t::-::"t::-t::-1t=:'-r!J1"

~

for

which

the

breaker

will

not

trip

- , /

--

---1---j--J--H-t

s

If

the

overcurrent

subsides within

-i---------

-7

that

time

to

BOo/

0 or less

of

the

----f-+-++-1,.:--l'.f-l'C,Af--+-- -

--H-+-H----;--

---l-f--1r+-+-H •

-·--~-.

,~~

·ll'/'-Al--+--1--f-+-++-i++--·--l--+--.;e--r-;-

t-

s

breaker

long delay pickup setting.

~

--

·

11

the

duration ot

overcurrent

ex-

+--t-l-1-HPl<cHf-/Tll---1--1-+-t+-H+l----+--+--f-l--l-+++-1

4

coeds the time ,indicated by the -

---1-H-l~+.H-/;f--f----

--

--·-

-1-1-t----1--1-

-

---1--

resettoble

delay

curve,

the breaker " V

overcurrent

device may not reset

+--t-l-t-ttf'k'cll-7-t--t---1--+-I-

-

and may

eventually

trip

the

I'"

'/

3

'

.t

==

:@

:::~i::r~le

only

where

fault

current-~

-r-

~'

"/'.\

=i_:-

1

.09-

- - does not exceed

42000

A(rms

sym)

·~~~~~~111-~~~~~~~-

~,1-li!ll,j(';?l(<;l;~l(l-1-11!~-

.09

.08

--

- /

=J-

08

.ol--

1---

f.i\ A

I'

bl

1 h f

It

t -

I--

r-

-j·

- - o7

,

06

__

_

__

o,;:_;

pp

1co

e

on

y w

ere

au

curren

-·I

_-

06

,

05

_ _ does not exceed

50000

A(rms sym) I _

~

/

oe

""'"y

.04--

--

®

Applicable

only where

fault

current

-1-----

--1----

K x x x

1x

x x

1x

><

.)

1

-

04

,

03

___

does not exceed

65000A(rmssym)

_

03

·

02

--

-+++---1---·

--

-1--

1

- -

·-·

__

__,

_

_l_l-1-~~~'~jl\~,~~x/~~~~v~,~:~~~~x~,~~~.~x·S:~'~x~~R~:~~~f+~I

02

1-

)(x

x)C

X

H-+++1----f---+-+-+--!-H-H----1--

-

·

01

s 6 7 6 9

10

20 " x x x >

0

2

current

in percent

of

breaker

trip

unit rating

Fig. 7 - Tripping Characteristics

of

Standard Series Overcurrent

Tripping Device with Long Delay and Instantaneous Eletnents

g

1l

x

Courtesy of NationalSwitchgear.com

•

)!

0

u

•

0

•

E

current

in

percent of breaker

trip

unit roting

~ ~

o~

0

o 0

o g0

08

g

2 2 2 0 0

020°8

°o

0

o 8 8 °

g2g8

8

1888

~5~6~7~ar:•r:10~~~~20~~30~~40~50~g~g~g~g~~~~~l~~~~~l~~~~g~g~~~~~-~~~tg~~~~f~~g~g~g~g~~~~~~~~~~~~~~~2~~~~~g~o~igo

8001-1-

-

-·-

j-

800

1001------1--t--

·r--+--+---J-t-+-nc-c----1·-

700

6001-t-r-

-

f-+-+-il-+++----l-

-

600

ooor-1-1-t--i-r---r--+----+-+-+-i'

l-ltr"-lr-~t--1---c--+--j--4-~-1---~------i-+--+--+-+-j-4f-+-----j--->----i->-->-+-+-J--10oo

400

-1-1--H-t-----+---1---f--1-l--HiH*-''lfl--+l"'c--t----l---I--

- - -·'--

--'-~·---+--+--+->-I--

--

-

400

long delay pickup

setting

~adjustable

with

calibrated marks

at

80,100,120,140

1 and

---t----+--f-+-t--1-++;•oo

160 percent of

trip

unit roting

2oof--i-+I

H+-----t--r·-++-1-1-~+l~'-l&-l--I-=

~If.iring

time~W_WJ±=:===:=:==::=:-+.

_"._"

200

,,..

100°/o pickup

and

30

second long delay settings

/ /

100°/

0 pickup and

20

second long delay

settings

igg-------~~~D~D~lillltt~~~~~~~~[~j['~t~f'1~-r~6!o!

0

!.~o~pr~c~k~upvo~n~d*3~o~s~e~c~o~n~d~r~o~ngijd~o~ra~y~s~e~tt~i~ng~s~-~~1~l:~l~i11j::j~8o

eo

--·

J<,

'"

f-

-

eo

70

---

J<.

'"

/ /

1-

70

H

~H

®

')(

)(\

'"

50

-resettable

delay

2 \ A

~1.1

50

4

o--

-100°;

0 pickup and

30

second ,

1-

40

__

~

long delay

se

ttlngs

-'-lf-1--f-'1-~t\<\olll".fJ'"i<""'t°"r'llt

1

'--"t"-1'11l"!"i:lt--.rl-

30

100010

pickup

and

20

second

....

I I \_

\'.~

./-.)'

x llrt.

'\.

'"

1'

r~

long

.delay

setting a adjustable with

loni

delay

settings

IJ~l"---\.==~.l~~~~JG~~~

'~-~J11--.£

·~~f---__'.'.ca~l~i~br~o~t_'fe~dtm't'atrk"fs't-'a~t_.::_30:'._'a~fn'-'d'.:2~0~s~e~c~o:ntd:s

1

_j

20---

80

Yo

pickup and

20

second.tj:

long delay

settings

r---__:\'

·x[)cl' "

"-

-···--

-----

--1- -

-

'

--

-

2--

--

'i'~1.J"i

/\x

""

I'

1~r_-t-

__

t-1-H-

__

----i--r~~c-=~-~~i-~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~=

8f-l--+Hf-++---~---

7C-HHC++----1---

'\

6--.-1-1-1----+---i-+-+--i

'/

-

5-

trip

unit roting (amps)

f--C\.1

1"-7/,,A-+l'<+ll----/-,.+...-short delay pickup

setting

-adjustable with

4r-

~minimum

bond

intermediate

band

maximum

bond

/i

~

calibrated

marks

at

500,

750,and 1000

1600 1600 1600 v

I'

/ percent of trip unit roting

:~gg

:~~

:~gg

r--1>,/"'"'Hl-+-t&H'---+--t-~-n==-11-n

__

-

--~

600 600

600

v

I/

~

1·--1

tt-1-r--

500

500 500

+-H-H

short delay setting

~adjustable

with

400

V

,1

colibrated marks

at

30,14,and 6 cycles

I~-

350

/ r 1

--

30

20

10

'

7

6

'

4

'

2

I

.9

..

::,--+-+-t-+OOf&S:

-

~

·l--+---+--+-+--1·

·--

•7

CD

.6------

1 Total cleoring time is

the

duration I I I 1

--

-h

1

f----+--f--t-

.+--t-H-ti

6

of

fault

current flow, including

arcing time.

""-"'

"..!'..

"'-'ma,imum,

Resettable deloy curve

shows

the

--

__

....__,_,

_

!'....

,

i~?o~~d

~~~l"-

ollowoble duration of current flow

I.I/

·

..

1

..

......._"

l

"'..'I

'-.1

''"

for which

the

breaker will not trip

+-+-lt"'--}<\-+·Hl-------1--1'-~'~'I'''

·&"'+'~,!'

14

cycles

.5--

.2

f--i-++-1-

(

30

cycles

-i---r-

-o

.4

+-l-+--+----l--l-1-~-++13

2

.ok--·-

.oe-

--

.07-·-

.06H-+-++

.05:-+-+++

.04:-+-++-I

if

the overcurrent subsides within / /

H---+---}~~in;~r~edlate

~·-

_

=f

__

that time

to

eo

0

/o

or less of

the

-1---1--tt?f-/_,,/~ll.+

'"

bond

[',

'1'.

r--

----

-

breaker

long

delay pickup setting,

~==~=t1

2

-'~l/~~-'zj'~~~2;~~$

•

2

,~~~.~~-'~';t'~i=~=~:::1$~=1=1=!:$S

1

If

the duration of overcurrent

ex-

_ 6 cycles

09

ceeds

the

time indicated

by

the

-

1

--==l=::P\:JZl;:Rtf;f;:~'-z_'.;:;1'~';zJ~~;:;;;~"J;?(J==-=--=J==J=+~=

1

=

g~

i

.03-~r

@

.ozf--

_I

__

_

'

resettoble delay curve, the break-

-f--

/ / / /

minimumA--Vr-+11-----l

os

er overcurrent device

may

not

+-+-l-''b-'Hl4tl4-//'--,'-c/,/V'--;Abond

+>''H-"l-,l<ll----+'--r-+-+---+--i--l-4-4

os

reset

and

may

eventually

trip

the

'-

/ / / / / / V /

04

breaker.

-r==~==~~~~~~/~;:;;/~~/~~~~~~~~====::=i::=::=~~~~~ttl

These curves applicable

where

fault current

does

not exceed

42000

omperes (rms

sym)

total cleorinq time Q)

-1-----t-I

lt--

resettable

delay®

03

02

' ' '

-1

" i

'i

.ol5'--c6~7-o,:-.o-,too--~,c'o-"a~o,--•'°o~s

7

o°'g:-g

0

'-'~"g°'g"c-----=£---=2-~=---;ge-!g--=~-!g~g°'g!o------c~"c--~C:---~C:---=~--=§"~''-c!~-!~"§:-----;§!;-~§!o----;g!;-g*"g~g:-o-;;g>;g:>\§·

01

" - Cl;

I')

~

s

16

g

~g£

current

in

percent of breaker trip unit roting

Fig. 8 -Tripping Characteristics

of

Selective

Series

Overcurrent Tripping

Device

with Long Delay

and Short Delay

Elements

•

~

0

u

•

0

•

E

"'

.--.,.

(

'°'>

.:~.cY

Courtesy of NationalSwitchgear.com

:.1

I

1

/

C''•

':

f7>1

'<:,_

':>'/

'

·"

..

.>

..

.>

·""

.00

M

.oo

·"'

Page

19

t

±tl±±:tffJ

'"'

'"

00

h-1.-14~

rn

-

--

GO

'

..

'

l~H.~~'

+;;cH-H~.o

..

!

~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~'

"

...

·"'

.oo

·"'

·°'

·"'

40

eo

eo1oeo90~

ill

~

;

~~~*~Hi

CURRENT

IN

Xf\1J1ml!:S:PERCENT

OF COIL RA'l'fNG

Fig. 9 -Tripping Characteristics

of

Special

Series

Overcurrent Tripping

Device

with Instantaneous Ele1nent Only

Courtesy of NationalSwitchgear.com

Page

20

Fig. 10 -Schematic Diagram

of

Standard

Overcutrent Tripping

Device

with

Adjustable

Long Delay and

Adjustable

Instantaneous Element

][

I

N

chamber

T by

the

various

valves

Hand

K.

\¥hen

the

diaphragm

has

reached

approx-

imately

60

percent

of

its

travel,

a quick

release

valve (shown in

Fig.

6)

is

mechan-

ically

opened.

This

quick

release

feature

permits

the

full

force

of

the

magnet

to

be

used

for

tripping

the

breaker

after

the

timing

cycle

is

completed.

At

higher

cur-

'

-.,

rents

when

the

attraction

between

the

mov-

ing

core

C and

the

stationary

core

B

is

greater

than

the

load

on the

spring

inside

of

the

moving

core,

the

moving

core

will

compress

the

spring

and

travel

independ-

ently

of

the

tripping

stem

F,

This

spring

insures

a

constant

force

pattern

acting on

the

diaphragm

E.

The

reset

valve

is

shown

as

G.

Valve H

is

the

long

delay

valve and

it

is

permanently

open to a

calibrated

setting.

This

setting

which

controls

the

tripping

time

can

be changed by

means

of

dial

S,

Figure

10. The magnitude of

current

at

which

the

--~--

D

A

--4

T

s

G

long delay will begin

to

operate

is

deter-

mined

by

the

long

delay

pick-up adjusting

knob

P,

Figure

10. The magnitude of

current

at

which

the

instantaneous

trip

will

operate

is

determined

by the instantaneous pick-up

adjusting

knob

N,Figure

10,

2.

Dual

Selective

Overcurrent

Series

Tripping

Device

For

Group

or

Tie

Breakers

The

operation

of

the

dual

selective

tripping

device

is

similar

to

that

of

the

dual

overcurrent

tripping

device except

that

for

this

device

the

following

details

are

included:

A. A

short

delay

valve

J,

Fig.

11,

con-

trols

the

size

of

orifice

and consequently

the

tripping

time

in

the

short

circuit

re-

gion.

This

orifice

is

adjustable

by

means

of knob R.

Courtesy of NationalSwitchgear.com

Westinghouse DB-50 User manual

Popular Circuit Breaker manuals by other brands