Westinghouse Db-50 User manual

(·'

'-'~I

Instructions

for

Types

DB-50,

DBF-16

and

DBl-50

Air

Circuit

Breakers

Westinghouse

Electric

Corporation

Switchgear Division, East Pittsburgh, Pa.

I.

D. 33·8.50.JL', Effective

March,

1966. Supcrsl'dC's

I.

B. .l'l·H50·3-B,

May,

1965.

Courtesy of NationalSwitchgear.com

t

·r

\... .

lable

of

Contents

Part

1 - Receiving,

Handling,

and

Storing

l

nspecti

on .

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

Hemoval

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

,

Heverse

Current

Trip

Attachment.

Field

Discharge

Switch ,

Auxiliary

Switch

..

,

..

, .

Alarm

Switch

Attachment

•.

Electric

Loclrnut

Attachment

Key

Lock

Attachment

,

.•.

Key

Interlock

Attachment

•.

Hectifier

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

•

Courtesy of NationalSwitchgear.com

re•

!

i

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'

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I

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

Type

DB-50

Fixed

Circuit

Breaker

Outline

Dimensions

and Mounting

Details

. . . • . . . . . . . . . . . • • .

Type DB-50

Three

Position

Drawout

Outline

Dimensions

Typical

Wiring

Diagrams

-Type DB-5U

Fixed

Circuit

Breaker . . . . . . .

..

. . . . .

~

. . . . . . . . -. .

Cross-Sectional

View of Type DB-50

Circuit

Breaker.

Type DB-50 Spring Closing

Assembly

.....•.•.

Type DB-50

Three

Position

Operating

Mechanism

.•.

Series

Overcurrent

Tripping

Device

with Long Delay and

Instantaneous

Elements.

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

Series

Overcurrent

Tripping

Device

Showing

the

Assembly

of

Calibration

Case

to Magnetic

Circuit

. . . . • . . . . .

Cross-Sectional

View of

Series

Overcurrent

Tripping

Device

with

Long Delay and

Instantaneous

Elements

• . . • . •

Tripping

Characteristics

of

Standard

Series

Overcurrent

Tripping

Device with Long Delay and

Instantaneous

Elements

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

.

Tripping

Characteristics

of

Selective

Series

Overcurrent

Trip1Jl.ng

Device

with Long Delay and Short Delay

Elements . , . . . ·. . . . . . . . . . . . . , . . . . .

Tripping

Characteristics

of

Special

Series

Overcurrent

Tripping

Device with

Instantaneous

Element

Only • . • •

Schematic

Diagram

of

Standard

Series

Overcrnrrent

Tripping

Device

with AdjustalJle Long Delay and

Adjustable

Instantaneous Elen1ents. . . . . . . . . . . . . . , . . . . .

Schematic

Diagram

ofSelective

Series

Overcurrent

Tripping

Device

with

Adjustable

Long De.lay and

Adjustable

Short

Delay Ele1nents . .

_.

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

Schematic

Diagram

of

Series

Overcurrent

Tripping

Device

with

Instantaneous

Element

Only . • . . . • . . . .

Discriminator

for

Tripping

Device . ,

•...•.•••.

Closing

Solenoid -

Construction

Details

. • • . • . • . .

Control

Relay -

Adjustment

and

Construction

Details

..

Shunt

Trip

Attachment

-Location&

Construction

Details

.

Undervoltage

Trip

Attachment

-

Construction

Details

.•

Undervoltage

Time

Delay

Attachment

-

Construction

Details

Reverse

Current

Trip·

Attachment

-

Construction

Details

.

Field

Discharge

Switch -

Construction

Details

..

Auxiliary

Switch -

Construction

Details

. . • • . . . • . .

Alarm

Switch

Attachment

-

Construction

Details

. • . • •

Electric

Lookout

Attachment

-

Construction

Details

.•••

Key Lock

or

Key

Interlock

Attachment

for

Fixed

Breakers

-

Construction Details. . . . . . . . . . . . . . . . ,

Rectifier

Unit

for

A-o

Electric

Lookout

Attachment

•

Type DBL

Air

Circuit

Breaker

. , ,

...•...•.

10

11

12

l:l

14

15

17

18

19

20

22

23

24

25

26

28

29

31

32

33

34

35

36

Courtesy of NationalSwitchgear.com

i )

General

Type "DB"

air

circuit

breaker

is

designed

to give continuous and

reliable

service

as

the

protective

link betweenthe power

source

and

associated

productive equipment,

This

L>reaker

is

built to

operate

with a minimum

of

maintenance,

whilE!

at the

same

time

its

simplified

constructidn

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

determined

by

the se-

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 wel I as

on

coordination

and freedom of

all

moving

ports,

must

be

included

in the

mainte-

nance schedule.

Consult

Westinghouse engineer-

ing

and

service

personnel for recommendations

pertaining

to

special

operating or maintenance

conditions.

•

Courtesy of NationalSwitchgear.com

PART

1 • RECEIVING, HANDLING, AND STORING

Type "DB-50

11

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

lbs,

295

Ibs,

3-PoI e

2.80

I

bs.

355

Ibs.

Add

30

Lbs.

for

Drawout

Details.

Add

~5

Lbs.

for

DBL

Details.

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.

Report 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

tobe 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 inspectionshould

preferably

be

made

with the

breaker

in

its

permanent

mounting.

Inspect

the

breaker

as

follows:

1.

Raise

and lower the

trip

bar

by hand to

make

sure

that

it

does not bind.

2.

Rotate the manual operating handle

slowly in a clockwise

direction

to move the

contacts

toward the

closed

position. ·

a,

Observe

\\·bether all

pnrts

are

in

proper

alignment and move

freely.

b. Make

certain

that

the

studs

have

not been forced out

of

alignment.

o. Be

sure

that

the

contacts

are

clean

and

properly

aligned.

For

a dc5Cription 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

mechantsm.

b.

Tbe links

must

always be

free

to

move without

friction

or

binding.

5. Check the

attachments

for

operation

in

accordance

with the

appropriate

instructions

as

given under

"Maintenance",

Part

3 of

this

book.

NOTE:

It

is

not

advisable

lo

lubricate

any

ports

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.

STORING

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

...

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fi

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)

completinp; any scconclary

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.

Typical

circuit

ln·\·al\cr

wiring

diagrams

are

shown in

Fig.

2, The connecting

cables

or

bus

bars

should have adequate

current-

carrying

cap'1city, otlw,·w'o'C,

heat

will be

conducted to the circi.;it

breaker

resulting

in

possible

cxcc:'.S'.\C tc:Tq1crature

rise.

Connecting

cables

or

bus

bars

must

be

supported

so

thB

t the

circuit

brreaker

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 Voltage.s, Tripping Ct1t'rents1

Closing

Currents

and

Fuse

Ratings

---

-·---

.

Cl.OSI

NG

NOMINAL

RECOMMENDED

CLOSING

COIL

CONTROL

CLOS

I

HG

TRIPPING

FUSE

AMPERE

RATING

FUSE

SURDEH

VOLTAGE

AMPERES

STANDARD

NEC

STYLE

NUMBER

250

VOLT

600

VOLT

'--

-

-------

~----

---

211

DC

---

9. 5

48

DC

---

5.0

125

DC

18

2.0

10

I

20A823H04

250

DC

8 I. 0 6 I

20A823

ll03

'

STD.

230

AC

18

r

• 0

10

I

20A823

H05

460

AC

8 .2 6

120A82'1H03

575

AC

4 .3 3

120A824HOI

115

AC

---

I.

24

DC

---

9.5

48

DC

---

5.0

125

DC

128

2.0

40

120A823HIO

250

DC

62

I.0

25

120A823tl07

L

HIGH

230

AC

80

. 5

25

I

20A823110'1

460

AC

39 .2

15

120A8241105

575

AC

25

.3

10

120A824

H04

115

AC

---

I.

*For

A-C

closing

use

3

KVA

source or

larger.

Supplied fot

breakors

hoving

dual

overcurrent

tripping

devices

(Long

Deloy

•

Instantaneous

Type)

or for

breakers

having

dual

selective

ovorcurrenl

tripping

devices

(Long

Deloy·

Short

Delay

Type)

plus

discriminator

details,

6May

be

supplied

for

match

up

breakers

having

dual

seloctive

overcurrent

tripping

devices

(Long

Delay~

Short

Delay

Type)

without

discriminator

details.

•

Courtesy of NationalSwitchgear.com

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Three

Position

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Dimensions

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Page

9

PART

3 - MAINTENANCE

POLE

UNIT

Each

pole unit

is

mounted on a

separate

molclecl

base

through

which the

breaker

studs

pass.

(See

Fig.

3.)

The rnol ded

bases

are

attached

to the

steel

mounting

panel

and

provide

insulation

for

the

bre:tker

studs.

The

upper

stud and

co:1hc\

arc

attached

to the molded

base

by

two bolts.

Tho

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 ad-

justing

gap G to

be

.078-.093

inches.

This

gap

is

acljustecl 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.

OPEHATING 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.

notating

the

closing

handle clockwise

raises

the

lift link and

lower

spring

guide

to

compress

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 ofthe togglewhich

permits

the

closing

spring

to

complete

the

breaker

closing.

Slow

emergency

operation

to

check

the

contact

sequence

can

be obtainedby

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.

lt

is

designed

for

intermittent

duty only. Check

for

loose

bolts.

To

remove

closing

coll,

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

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---------------------------·---------·~

DB-50

CIRCUIT

BREAKER

L2illLAMI't;Rl;Sl,

29Q..l'Q1IS__A:Q

PUSH

TRIP

317

HANDLE

316

MOVING

ARCING

~£NTACT

-~-------

_·

MECHANISM

302

CLOSED

CLOSING

SOLENOID

303

~,FEL

PANEL-

•.

·ARC

CrlUTE

300

1

.STATIONARY

.

ARCING

CONTACT

314

··UPPER

STUD

\

313

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MOVING

CONTACT

312

__

--·TRIP

SCREW

lt'.!flkEilu:!J:;

311

'mf'\1i!fiiitttr%WER

COIL

TERMINAL

306

OVERCURRENT

TRIPPING

DEVICE

305

TRIPPED

OPEN

(RESET)

Fig. 3 • Cross-Sectional View

of

Type DB-50 Circuit Breaker

Courtesy of NationalSwitchgear.com

(.

)

l-'

d

[(I'

12

In

replacing

closing

coil be

sure

to

re-

place

brass

tube

(5)

so

that

stationary

core

(4)

anrl moving

core

(3)

are

aligned in the

tube.

He-assemble

closing

coil and

details

in

reverse

order

from

removal.

If

the

eircuit

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 anq moving

core

and

bring

out

through

the

u-shaped

foot on

breaker,

He-assemble

closing

coil and

details

in

reverse

order

from

removal.

Take

care

to align

stationary

core

(4)

and moving

core

(3)

in

brass

tube (5).

OYEHCCHHENT

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

FIRST

TOGGLE LEVER

MECHANISM

HAN::J\_E

PUSH

TRIP

PUSH

LIFT LINK

TOGGLE

LINK

PUSH

LINK

UPPER

__

SPRING GUIDE

LOWER SPRING GUIDE

SPRING MECHANISM

DB-50

CIRCUIT

BREAKER

1600

AMPERES,

600

VOLTS A-G

Fig. 3A -

Type

DB-50 Spring C/osinll

Assembly

·CROSS

,BAR

TRIP

BAR

.LATCH

PLATE

SPRING

~.

•

Courtesy of NationalSwitchgear.com

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11

PRESS

LATCH

TO

REMOVE

HAfl<'DLE

Fig.

3B

-

Type

DB-50 Three

Position

Operating Mechanism

-;.-01

w

,

7'.

0

~

Courtesy of NationalSwitchgear.com

"\

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 oan

easily

be removed

from

the

breaker

and

replaced

with anotherunit 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

lo

prevent iI

from

fol

Ii

ng.

To

install

the

overcurrent

trip

to the

circuit

breal,er

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 hexagonhead,

steel

bolts 2-1/2 inches

long shown

at

A,

Fig, 3. Use only one look

washer

under

the head of each of the bolts.

Care

should be tal(en to make

sure

thatbolts

A

6

Fig.

5 # Series Overcurrent

Tripping Device Showing the

A.ssembly

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

£2_mpletelr

disconnected

from

any

normal

voltage source.

The

trip

screw

mounted

on

the trip finger

above the overcurrent tripping device should

be

adjusted

to

get

the

some

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 overlravel 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

delaydevice

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

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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 oan

be engaged to lift the

trip

plunger against

the

trip

screw.

Close the

breaker

and move

the

trip

plungerupward 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

thatnormal

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 overcl!rrent

tripping

device

ls

air

de-

layed with all of

its

elements

completely

adjustable. A typical unit

ls

shown ready

for mounting

on

a

circuit

breaker

pole unit

in

Figure

4. · ··

The tripping device

consists

oftwo main

subassemblies

namely:

l,

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 Jong delay,

short

delay and instantaneous

characteristics

of

the

circuit

breaker

tripping

curve.

Courtesy of NationalSwitchgear.com

Pa(.'e 1G

Time-Current

Classifieation

The

overeurrent

tripping

dcviees can be

supplied

with any eombination of the

three

tripping

elements,

namely,

longdelay,

short

delay,

and instantaneous

elements.

The

most

popular

eombinations

are

listed

below:

1.

Dual

Overcurrent

Series

Tripping

Device

This

unit

has

an

adjustable

long delay

and an

adjustable

instantaneous

element,

the

eharacteristic

curve

of which

is

shown

in

I'

igure

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.

Calibratedmarks

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 variouE l:lements

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

al

30

and

20

seconds,

Calibrated

marks

at

20

and

12.

seconds

or

at

60

and

40

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.

~s

Trip

Only

This

device

is

equippedwith an

adjustable

instantaneous

element

only. Atypical

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,

andthe motion

will be

retarded

by the

diaphragm

E,

The

rate

of

travel

ofthe

diaphragm

is

determined

by the

rate

at

which

air

is

permitted

to

enter

•

Courtesy of NationalSwitchgear.com

•

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£

1'-~

I

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e 17

100

600

&00

400

•oo

200

100

•o

80

70

00

•o

40

•o

20

10

•

1

•

4

•

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1--.

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-·H-r---t--t-i-+-t-+-H-1

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--

-.

'"'

-

---

-

.(JO

----

--

.07

--

.04

·--

- -

.04

--

-.

Resettable deloy cvrve shows

the

a11owabl•

durallon

of

curront flow

l~~~~~fMt~-~-~~-~~-r-~~~~;-----

~·-""

,:.,.

~

for which

the

bteoker

will

not

trip

-

-+--+--1-

--r+-1+--·-+--t--+-+--

- •

If the overcurrent subsides

within

-

-1-

-i-i+H---+-+--+-1-++·l-H

7

that time

to

80o/o

or

less

of

the

-

~

,,

-----1--1---

~-

- - - •

breaker lono deloy pickup

••!ting.

-

--

--1--;-~

·

I"\

·f'/-7'tt---l---t-r-1-++1-1-1----+--+-t--j-

-~

•

If

the

durotlon

of

overcurrent

111.w

+-+-++-HP'k:H/'-/1--f---t-l·-f-++1+'1---\--

--

-·-+-1-1-H-I

4

ceed1

the time

lndicottd

by

1ht

_

~·1'.l.f-.t<.J.-1--l-r-,____-

-+-J-+---+--1-----

-r

a

resel1oble delay curve, the breaker

'~

'/

.

overcuatnt device

may

not resit

·l··Al---1---

--~

-•-++.,+---~--t·~-t

-+-+l-+-H~

I

ond

may

tventuolly

trip

lht

-...

h

breaker. -

,~

/.·-A-+---j--1--1--H-l-I+--

Only

whtre fault currtnl...

~

t('/~~~~~-=i:--=

1

=--·-·--

_

--·

~

do••

not exceed

42000Alrm1•ym)

:::.i==:==-

=t=r:

s~

~

"""

__

_:;-:-=

-~--=-==-=t=-=_t_=1~-=

..

r=1_:+_1+1J

-

1----

r\.

~

Ot

r~K

-)-·

"'"

oe

do••

not

tKceed

t>OOOOA(rmatym) -

___

·-t~

~

_

"><

Oll

~

x

.04

--1·-

.o•

·--

~·

fault

current

--

·-

--

~r--.,

)ii

x A 04

does not'

exceed

65000Atrmseym)

_ .

~""'

J\.

x

os

I'

A)(

,.

)(

._)

,r--..

rY"'I<)(

P<

)(

.l'\.r..r..V'>..Y'<

·

02 ===

~

----r----+--

-1---=:

=I~

~-1

~-=·====~~=~~=~l~t,n~x~~~~Q~·~.~-~-~~~-~v!.~:1~~~x~~~~atUt-I

02

LJ_Llll_

__

J,.-CL.1.J.JJLJ_Li

__

_J,_j__l_llj_l'~~:)::l~~~~~;('.~~x~~~~~~X~x~K~,/"~>~~<'~-1-l.Jll.

o•,

.,

..

~

t•

'°

••

'°

sg

~~~

2

~ ~

~

§

~i§~

y

~ ~

~

n~~.

!"!

"1'

I~

It.,

current

In

p~rctnl

of br•oke.r

lrlp

unit rottnQ

Fig. 7 -Trippinll Characteristics

of

Standard

Series

Overcurrent

rripping Device with Long Delay and Instantaneous Elements

Courtesy of NationalSwitchgear.com

j

) u

i

IX

v_

.~

!

8h-

._L

7

6

·---

+---~

f7

/ short delay

pic~up

settlno

-adjustable with

1-

--

'\---¥'...,1

1

C

'11--!-llt-N-,.,L-+

callbroted marks ot

500,750,and

10.00

•

~·'trip

unit roting

(omps)

.,.

-··minimum

ban~-

__

lnt&rmediote

,_

bond

..!!,!Oximum

bond

~/1...

I/

percen1

of trip unit roting

.1

1

li~

1:

1

•

:·\11-J-'1!'.---l-+n=11nr·

l '

1~-_.,_,,_.,_~,_

1

500

1---lf.~l-!!'4Ji.,;-l--·-+-

1600 1600

1200 1200

1000 1000

·aoo

eoo

600

500

8hort delay setting

~adjustable

with

callbroted

marks

at 30,14,and 6 oyolet

400

~'--

350

•8

,,__1.-1--'-'

notes:

---b-

I~~

, ,

=~~~~'~":::_-:=-t-::-::-t-::-t-::-!i~·3j3f-f-f-t·__,_

__

-

___

....

1-+_

.....

____

~,__,"

___

_,_

1

_

__,_,_

...."-+l

7•LLl.J.J.

•--'-

CD

•

.

4-

~1-

h

•--"'

- ©

L

..

J._L_

Total

cleorlng

time

is

the

duration

of fault current flow,includfng

arcing time.

tldt:fmtl-~,~~~;:;1:;t.:;l:;):j:J:j:j~tl;:j

30

C;CIO~

--+---+--1--1-H

i--l----!I"'1c·>f--l-\--Jll~'\Y

''\.,~~'\.~:~~.l~=f+P(

-,

1

,

~"'

'\._

I'-"'

'mo,imum, \

I-+

Resettoble deloy curve shows the

bond

l..':i

f"..

-1-...:i~+---1

1

-

-·1-H+H

ollowoble

durotlon

of

current

flow

1'

1,

1.

•I,

"""'\

'\'-1';;.:r;:

I\

for

which- the breaker will not trif\ ·----'--''"-L"'J....

...

••

~~,;i....;i

...

,,;i..i.;

,>.1,;,.,.,,ii.4.,_,j.,\.--l--<

14

oycle&

if

the

overcurrent subsides

within.,..

...

l.;I/

~

~i)in~r~ediote-:.

---

--

·-0,....--1·-I-+·+

v

1,..

bond

,I'\ '

r..

400

aoo

200

100

90

80

70

80

00

40

•o

20

10

'

•

1

•

4

•

.~

••

.1

••

•

.2

.11---1-+-1+

.09

__

L,

- •

.oe

.07L-''

-'--'-'-

.<>eh-

I

-I.-

-

tho!

time

to

60°/

0

or

Jess

of

the

~

7

1--,l.aJ-l_J_J

____

\_

J:,

"

---L---

--~

-1--

-i-+-

breaker

lono

delay

pickup setting. 1

......

IL

~

· '\.!'.

r.

If

the duration of overcurrent

e>t..

~==--=1=-=--·

~~-~-zjit"~-tt~~;t'.~~~~i~---,~-~,,~-~o1f:~'.=~!6~c~vc[~'~•~•,_=-=~tt:~:t'-j~~I

:b9

ceeds

the

lime Indicated

by

the

~

--

1-

·I- -

·-

.oe

'

__

L.__

-

-·

.07

•••

,Q'3,L.L.

-

'-'-

- I

resettable

detoy

curve, the

brook··

+::=t:=~~A:tJ1tz~~~2(

minimum

7

1-.p.

---1-

,-++·+-H-H·o•

er overcurrent

device

may

not

-l

bond.~

k

--JLIJ----l---+-1---+--H+H

M

reset ond

may

eventually

trip

the

~Vi'....,L.,?-¥-,t.+,.<.'J,v-'

'l·A'-Y'l.c

1.

-----1--

-1-

_.1...

.04

breaker. , "

,,

totol clearing time

CD

L--

-·~--·-

--L-~-+-i-H-

.02

-resettable

delay©

Those curves oppl\coble where

fault current

does

not exceed

420~0

o~per~s

(~m~

s

1

y~>.

1

1-W--11--l--ll--l---+-.._j_.-l-

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

-

--~l----1--J-..J-1-""-~f+-I

20

3o

40

tios~gg~

current

in

percent

of

breaker

trip

unit

rollng

Fig, 8 • Tripping Characteristics

of

Selective

Series

Overcurrent Tripping Device with Long Delay

and Short Delay

Elements

•

g

u

•

• •

.E

!

Courtesy of NationalSwitchgear.com

'

•.,

.

••

'

..

·'

..

.•

..

·'

Fig. 9 • Tripping Characteristics

of

Special

Series Ovetourrent Tripping Device

with Instantaneous Element Only

f--

f...-

--1-l-

--

-1c-+c-+-

_;!-

-i..

-

--

l"

I-

'°

-.

•

'

•

Courtesy of NationalSwitchgear.com

l'n

['

r·

ZO

----------------·----_,

- .

--;t;.);:--

A

Fig. 10

·Schematic

Diagram

of

Standard

~

Overcurrent Tripping

Device

with

Adjustable

Long Delay and

Adjustable

Instantaneous Element

L_

I

N

chamber

T by the

various

valves

H and K.

When

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,

j ··

This

setting

which

controls

the

tripping

time

I

can

be

changed by

means

of dial S,

Figure

1

1 10. The magnitude of

current

at

which

the

t

I

p

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

Trippin[_flevice

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

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