Cutler-Hammer Automatic Dc Motor Starters Description

BELL SYSTEM PRACTICES SECTION 026-390-101 Plant Series Issue 1, September, 1927 AT&TCo Standard

CUTLER-HAMMERAUTOMATIC DC MOTOR STARTERS

( DESCRIPTION

1. GENERAL mounted in the rear of the panel and enclosed ) ' in a perforated sheet metal cover. In some in 1.1 Cutler-Ham.mer automatic DC motor stances an auxiliary relay with associated con starters may be used with motors ranging nections for controlling the starter from a in size from 1/4 HP to 7.5 HP where automatic separate circuit is also included in the equip or remote control is desired. ment. Each unit is controlled by an automatic Starters of this type permit a smooth start or remote control switch and is mounted either of the associated motor due to the time limit on the wall or on the rear of a panel in the method of acceleration regardless of load condi regular power board lineup. tions. With a given setting of the dash-pot, the 2.2 Stationary Contacts: The stationary con- resistor is always cut out of the circuit in ap tacts consist of hexagonal copper nuts proximately the same period of time. screwed onto studs mounted on the face of the Bell System Practice Section 026-390-701 panel. They are easily removed if necessary gives the installation and maintenance require (without disturbing the connections at the rear ments· for these starters. of the slate panel) but should last indefinitely with little or no attention. 1.2 Section 2 describes the starters and will be called "Description... 2.3 Contact Fingers and Support: The contact fingers are metal punchings equipped with 1 .3 Section 3 describes the operation of the copper contacts which may be replaced if the starters and will be called "Operation". contacts become rough or badly burned. 1.4 Section 4 describes the various conditions The support is a metal punching which which may interfere with the proper op holds the fingers in the proper position at all eration of the starters and will be called times, insuring their closing in the proper se "General Troubles... quence during the operation of the motor starter. 1.5 The following figures are attached to and form a part of this section. 2.4 CoU: The motor starter solenoid coil is clamped in an iron mounting frame and Figure 1 - Schematic Power Circuit for equipped with two screw terminals serving as Cutler-Hammer DC Motor connections for the coil. Starters. Automatic Control Figure 2- Schematic Power Circuit for 2.5 Dash-Pot: Each starter is provided with a Cutler-Hammer DC Motor dash-pot to delay its closing action. Either Starters. Remote Control oil or air may be employed as the delaying agent but the two cannot be used interchange Figure 3- Auxiliary Relay for Cutler ably. Hammer DC Motor Starters. Automatic Control 2.51 OU Dash-Pot: In this type of dash-pot the timing element consists of a cast iron 2. DESCRIPTION chamber into which is fitted a cast brass piston with a clearance of a few thousandths of an 2.1 Mounting: The motor starter is mounted inch, a needle valve, by-pass, and connecting on a small slate panel. Each starter has an port. The piston is equipped with a poppet valve associated resistance with i~ternalconnections arrangement for quick resetting. Variation in

Page 1 to

the

air

the

cir

the

out

suc

each

rate

time

high

close sole-

auxil

itself.

motor

motor dash

under

which of piston

circuit

action

starter of

starter

switch,

partial

contact circuit. of

closing,

starter

coil

through

immedi

the

and

auxiliary

an the

auxiliary

and air

from

supply would

automatic

such

the

resistance, the

of the

which

the

coil

the

contacts cushioning

the

oil

relay

the

normal

the

opening

starter

valve

resistance. of

to of

the

the to

the

shunting motor

motor

dash-pot.

control

piston

the

fingers

the

until

the

where

limits

by of

with by

motor

closing

The

relay

regulated voltage case

operate

the

movement contact

the

opens

valve

the

motor

starting

tripping for

circuit

closing

poppet

fuses and

otherwise is

that

time amount

valve. the

coil

starting

the the

the

energizing

coil

low

respects

governed

above

·forces

One

action

speed

controlling of

the

automatically

a the

the coil when

the is

relay

the succession

and

piston.

stopped all

the

needle turn

1). automatic

the

retarded

has

remaining

relay resistance

circuit Further

or The

which

for

with The

are except

the in

needle

completes

in piston

the

from

energized

shunted,

control

with

is an

the

coil

thereby

sufficient

Fig.

the

blowing

release

a the

the

During

permitting

used

upward

disconnects

the piston

prevents

opened.

switch

finger.

past

which

holding

(See

piston.

control),

closed similar

the which

shunting

motor current

up is

coil

series

portions

contact is

oil

shunted

dash-pot

Dash-Pot:

is addition relay interrupt

associated

quick of

circuit,

above beneath

This

and

causing

energized

solenoid

the

however,

upward

under are

opening

supply.

travels oil

thereby

The

flow,

noid Oil

The

pot is Air

pulls

relay the

and

contact

other

as operation

circuit

port

contacts

the

oil

the

(automatic

portions supply cessively

the iary The relay finger. its solenoid thereby completes

double-throw starter fingers control

open relay,

power starter. present circulating auxiliary as cuit, breakers

first

piston, 2.82 pressure piston ately

adjustment side

vacuum travels the of starter

acts consecutive coil of 2.83

oil

the

for

the air

are the the the

the

fur-

and

(4))

open

brass those

made

metal

draw

motor

power

the

starter

(6) be

and

(1) which relay

contacts

separate

External

diagrams

are

relay

limit

to Figures

would

when

operating

closing

the cast

and

the

with

battery)

control)

made

can

in to

in into the accomplished

motor the

place

normally

controlling

the

excepting that

pliable

relay

(pivoted

volt

contacts

connected

w1rmg

from

support in operated

motor

similar

across

auxiliary

of coil

the two order

switches,

auxiliary is

shown

(remote upon

starter two (5)

otherwise

relay

the

starter

(3))

both

the

piston

are

dash-pot

held

the

fingers accordance

valve.

of or

the

An and

installation. are

manufacturer.

motor

The

starter

The

contact

air

the

switch

which

opens

(8)

connected out.

instead

connections 3. wiring

Schematic

the directly that

deenergized.

2). an

circuit details

the

Where automatic

resistance

needle

armature

contact

the

Relay: stop

(7)

All energized

made

coil

The

Fig.

Operation

starters

made

pivoted

service,

Fig.

is moving

coil

with

the

diaphragms

particular the The the

of to

speed current associated

(8)

other

are

shunted

incorporated

Dash-Pot:

washers

(2)

(8)

the

these

energized

arranged

026-390-1

(See

spring the

(6).

the

piston

magnet

coil

(usually

coil

relay

The control

factory

when

outside

Air

nished

simultaneously.

controlling attached.

Refer Auxiliary

provided,

Resistance: bar so

General:

leather

magnet

coil

for

Connections:

Accessories

for

Theory

upward

adjusting

the the

the

single

switch

SECTION

the

tight 2.52 by operation plates

fitted piston.

to 2.6 (through dash-pot. and at remote

2.7 connections ings source

sometimes

2.71

a circuit. contacts of

cross relay

closed Page magnet

relay

2.72 present magnet

short-circuit 2.81 a 2.8

starter connects ISS 1, SECTION 026-390-101

effect is accomplished by air instead of oil. The CAUSE REMEDY ( rate of acceleration may be adjusted in the same 3. Loose Connections - Check Wiring manner as the oil dash-pot type. The air piston is not provided with a poppet valve for quick 4. Rough Contacts or) -Clean, smooth, release but the same result is secured by the air Contacts not ) adjust or replace as passing around the edge of the leather diaphragm properly aligned ) required on the downward movement of the piston. 5. Coil "open" -Replace 3. OPERATION 6. Resistance "open" - Replace 3.1 The operation of the motor starter upon 7. Dash-Pot Piston ) -Air Type- Clean the closing or opening of the starting cir sticking ) and Oil cuit (either manual or automatic) is entirely ) Oil Type- Clean automatic .and no further attention is required ) and of the attendant. ) refill ) Dash- 4. GENERAL TROUBLES ) Pot with ) fresh 4.1 The operation of the Cutler-Hammer DC ) oil. motor starter being entirely automatic upon the closing or opening of the starting cir 4.3 Incorrect Operation of Starter. cuit {either manual or automatic), unsatis factory operation (eliminating minor mechanical CAUSE REMEDY difficulties) will usually be caused only by an 1. Needle Valve open ) open circuit, failure of the contacts or gummed -Adjust or caked oil in the dash-pot. too .far ) 2. Dirt under Poppet ) - Oil Type - Clean 4.2 Failure of the starter to operate may be Valve ) and due to: ) refill

CAUSE REMEDY ) Dash ) Pot with 1. No Voltage - Check Service ) fresh 2. "Open" Fuses -Replace ) oil.

Page 3 AUTO.

VOLTAGE TO

REGULIITOR

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RUN

START)

Starters

Motor

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Cutler-Hammer

for

RES.

Circuit

Control

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Automatic

-Schematic

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Fig.

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026-390-1

sw.

D.RD.T.

SECTION

Page &

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