518-410-100_I6 - 6A Key Telephone System Identification & Installation

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BELL SYSTEM PRACTICES

Plant Series

SECTION 518-4 10-1 0

Issue 6, November 196

AT&TCo Standar

6A KEY TELEPHONE SYSTEM

IDENTIFICATION AND INSTALLATION

1. GENERAL

1 01 This section 1s reissued to include the

following:

• 227B key telephone unit (KTU) replacingthe 227A KTU which is rated MD.

• Show 229B KTU as an additional choice forsingle add-on transfer circuit.

• Installation information formerly covered in

individual6A arrangement connection sections.

Since this reissue covers a general revision, arrowsordinarily used to indicate changes have beenomitted.

2. IDENTIFICATION

PURPOSE

2.01 The 6A Key Telephone System, available in

three arrangements ( s e l e ~ ~ . ~ ~~ . and two-talking link), is a single and/or 2-digitdial selective intercommunicating system designedprimarily for on-premise operation. However, with

the use of a long line circuit, remote stations haveaccess to the local 6A system facilities.

DESIGN AND OPERATING FEATURES

2.02 The 6A Key Telephone System offers avariety of service features to the customer

depending on the type of basic arrangement (selectoronly, single-talking link, or two-talking link) installed.Some optional features can be obtained by strappingchanges on key telephone units; other featuresrequire the addition of key telephone units.

2.03 The selector only arrangement (Fig. 1)

provides for:

(a) Access to a colmUon talking path for amaximum of 36 stati61l .codes.

(b) Rotary dial station selection.

(c) TOUCH-TONE® dial station selection utilizinthe 247A (MD) or B key telephone unit.

(d) Line busy lamps.

(e) Station signaling over a separate pair bmeans of a single-spurt audible signal.

(f) Preset Conferencing: This optional featurenables a 6A station to simultaneously selec

and signal a group of preselected station

(maximum of six) by means of either a diale

code or the operation of a signal key. Severapreset conference arrangements may be provideat an installation and a particular station caappear in one, all, or none of these. Assignmenof a single or 2-digit dial code for each prese

conference reduces the total number of 6A statiocodes in the system by that amount.

Note: For transmission reasons, prese

conference-connected stations should not b

bridged onto a central office or PBX line bmeans of the add-on conference circuit of th6A Telephone System.

(g) Off-premise Stations connected to the 6Asystem by means of a long line circuit wi

provide satisfactory transmission if the followinconditions are met:

(1) All off-premise stations must be equippe

with 500-type telephone sets.

(2) The maximum external loop between th

off-premise station and the long linecircuit (225A KTU) shall not exceed 500 ohm

when operated at a minimum battery potentia

of 20 volts.

(3) Off-premise stations that may be connecteto the add-on conference feature shoul

not exceed a 1000-cps loss of 8 db from thstation to the serving central office.

© American 'Fe.lephone and Telegraph Company, 1967

Printed in U.S.A. Page





BU SY TO NE

FLA SHINGLAM P

INTERRUPTE D

RINGING

r--

'

lB KTU32

EL E

MEC H

FLA SHRIN G

CTRO -

ANI CAL

, WIN K,,AN D

E OUTIM Ci RCU IT

I PE R SYS TEM

214B KTU (M D)

SI NGLE -LIN K BATTERY FEED

AN D 9-STATIO N

SIGNALING CIRCUIT

19 B K TU ,

20 9A KT U, OR

21 2A KTUFLASH! NG

CIRCUIT

215A KTU3-STATION

SIG NA LIN G

CIRC UIT

21 7B KTU

CO NF ER EN CE

TIM E-OU T

C IR CU IT

227 8 KTU

STAT ION

BU SY

CI RC UI T

-- -

..__

.._____

f - - BU SY TON E

'---1--- - FLASHING

LAMP

,. . .---

·.-

' - - -

r--

._ __

I PER

AD DI TIO NA L 3 STA TI O NS

I PE R

SY ST EM

I PE R

3 STA TIO NS

ISS 6, SECTION 518-4 10-1 0

21 6A KTU

TRANSFERCIRCUIT

207 C KTU

SELE CTOR

CIRCUIT

I 24 7B KTU

TOUCH-T ONE

AD AP TE R

CIR CUI T

21 7B KT U

PR ES ET

C O NF ER EN CE

CIRCUIT

22 7B KTU

SIN GLE Ll NE

ADD -ON

TRAN SFER CIRCU IT

229B KT USINGLE OR

MUL TIPLE LI NE AD D-ON

TRANSFER

CIRCUI T

22GB KTU

ADO-ON

CO NF E R EN CE CIRCUIT

224B KTU

BU SY TO NE

AND CAMP-O NCONTR OL

CIRCUIT

22 7B KT U

RINGINGAND TONE

CONTROLCIR CUIT

22 5A KTU

LONG LINE CIR CU IT

227 B KTU

AUXILIARY

REL AYBUS Y LAMP

CIR CUIT

22 78 KTU

AUXILIAR YRELAY

LAMP FLASHCl RCUI T

I PE

ADO

R

ITIONALDE Sco

I PE

SYS

R

TEM

I PE R

TEM YS

I PE R 2

PRE CON

SET FERENCEANG EM EN TSRR

I PE R 3 CO NT ROL

TIONS TA

OR I G NATING

-O NFERENCING

AD D CON

I PE R CON TR OL

TION

GI NATING

-ONFER ENCING

STA

OR I

AD DCON

I PE R CO ORPBX L l NE TO BE C O N FE R EN C EO

f - -

I PE ~ ~ -

TO KEY

TELEPHONESYSTE M

R SYS TEM

DIAL TON E

BUS Y TO NE RINGING TONE

STA TIO N BUSY

I PE R SYSTEM

IPPED WITH

L TO N E AN D

ERRUPTEO

GING

EQUDIAINTRIN

I PE R OFF MISE

TIO N PRE STA ~ TO OF F

PREMISESTATION

I p

WHER SY ST EM

EN OVE R 40

Y LAMPS US

I PE R SY STE M

WH EN OV ER 20ULTAN EOUS SHI NG LAMPS

SIMFL A

Fig. 2-Single-Link Arrangement Using 2148 KTU (MD)

Page



SECTION 518-4 10-1 00

.BUSY TON E

FLASHING

LAMP

INTERRUPTED

RINGING

Page 4

----

r - -

232B KT U

ELECTRO -

MECHANICAL

FLASH,WINK,

RI NG, AND

TI ME OUT

C IRCUIT

I P ER SYSTEM

216A K TU234A KTU

TRANSFERSINGLE LINK

CIRCUIT BATT ERY FEED,

9-STATION

SI G N AL IN G

CIRCUITS,

SELECTOR

AN D 215A KTU

TRANSFER.___

3-STATIONSIGNALING

CIRCU IT

217 B K TU

'- -- PRESET

CONFERENCE

CIR CU IT

19B KTU,

20 9A KTU,

OR-BUSY TON E 227 8K TU

212A KT USINGLE LINE

r--- ADD-ONFLASHING f-- FLASHING TRANSFER

C IR C U IT LAMP CI R CUIT

2298 KT U SINGLEOR MULTIPLE

,.- LINE ADD-ON

TR ANSFER

CIRCUIT

,____

2268 KTU

ADD-ON . . . ._

C ON FE R E N C E

CIRCU IT

224B KT U

BUS Y TONE AND

CAMP- ON

....--- CON TROL

CIRCUIT

...._ 227B KT U

RINGING AN D

TONE CO NTROL

CIRCUIT

I PER

247B KT U SYSTEM 2 25 A K TU

TOUCH-TONELO NG LIN E

ADAPTERC IRCUIT

C IR C U IT

I PER

2178 KT U SY ST EM 227B K TU

AUX ILIARYCON FERENCE

RELAY BU SYTIME- OU T

LAMPCIR CUI T

CIRCUIT

I PE R227 B KTU

227B KTU 3 ST ATIONS AUXILIARY

STATIONRELAY LAM P

BUSYFLASH

CI R CUITCIRCUIT

Fig. 3-Single-Link Arrangem ent Using 234A KTU

!PER A DDITIONAL

S WHEN

MI S OVE R

9 CODE

SYSTE

18 COD ES OR WHEN SY STEM

R 9 CODES USING

KT U

IS OVE

24 7B

I PE R

AD DITI ONAL

TIONS ST A

I PER 2 T RESE

CONF ERENCE

ARRA NGEMENTS

I PER

ST ATI

ORIG I

CO N F

!PER

ST AT I

OR IG I

CONF

I PE R

3 CON TRO L

ONS

NAT ING A D D - ON

ERENCING

CO NTROL

ON

NATING ADD-ON

ERENCING

CO OR

PB X

BE C

LINE TO

ONFERENCED

f--

I PE R

f---+f---+

TO KEY TELEPHONE

SYSTEM

SYSTEM

DI AL TON E

BU SY TONE

RINGING

TONESTA TION BUSY

I PER SYSTEM

PPE D WITH

TO NE AND

RRUPTED

lNG

EQUI

D IA L

INTE

RING

I PE R OFF-

PR E MISE STAT ION

1----+TO OFF -PREMISE

ST ATI ON

IPE R SYS TE M

WHE N OVER 40

Y LAMP SUS

IPE R SY STE M

WH

SIM

EN OVER 20

ULTANE OU S

SHING LAMPSLA



(j) Automatic cutoff of all, some, or none 0L

the associated stations. Stations that ate

wired for automatic cutoff are prevented, onpickup, from being transferred onto an exillting

talkibg connection on the link.

(k) Rrnging tone to the calling statioo wheninterrupted ringing is provided.

(l) Off-premise stations as described in 2.03.

(m) Preset conferencing is an optiGnal feature

that enables a 6A station to sE11.ect a groupof stations (maximum of six) by means of a

dialed code or the operation of a signal key.Several preset conference arrang ments may beprovided at an installation, and a articular stationcan appear in one, all, or no of these. Use

of a dial code for selecting a reset conference

would reduce the number of A stations on thesystem. The visual signal i used to indicatethe progress of a confere e call. When aconference call is originated. the calling station

has a steady busy lamp, anrl the called stations

have the flashing line lamp. As soon as thefirst called station answel1S, the calling stationlamp begins to flash and ctmtinues to do so untilall stations have answertfd. All lamps then gosteady indicating that the conference is nowcompleted. The preset conference unit (217B

KTU) provides a time" release of unansweredstations. I t eliminates .continued ringing of ·an

unanswered station be(!, approximately 30 secondsafter the calling patty goes off-hook. lt alsostops the flashing lamps of all conferees, silences

the busy tone if one of the called parties isbusy on the s y s t ~ m . and allows camp-on to beused.

Note: Fo:r: transmission reasons, preset

conference-connected stations should not bebridged onto a central office or PBX line bymeans of the 6A add-on conference circuit.

(n) Selective conferencing is available where

pushbutton signaling has been provided. Theconference is called by operating a number ofpushbuttons (maximum of six) simultaneously.The visual signal is used to indicate the progress

of a selected conference call, as described inpresJ!t conferencing.

ISS 6, SECTION 518-41 0-1 00

(o') Camp-on is a feature that allows a 6A s t a ~ o n ,wired for automatic cutoff, to go in over

the 'busy lamp, indicating the system is busy,

and dial a stat ion code. The dialed .tode isstored I'l:l the selector. The calling station receivesa busy t\lne indicating to him, as well as to any

other staf>ion which subsequently picls up, that

the system is now camped on. Whe1! the systembecomes f r e ~ , the previously sele<ted station isautomatically signaled without flrther operationby the calling .station. S t a t i o r ~ not wired forautomatic cutoff cannot orightate the camp-on

feature, as they Wi>uld immediately be transferredonto the primary 1\nk on p ~ k u p .

Note: When the SA ~ s t e m is equipped withstation busy circuits, '1. camped-on call will notcut through until all station busy circuits arenormal.

(p) A station busv circuit causes a station, soequipped, to :JPpear b u ~ y to the 6A system

whenever that s t ~ t t i o n is off-hook and connected

to any line othEt' than the 6.1. line. This circuitprovides for busy tone to ~ returned to the

calling statior1. To provide this service the 6A

system must be equipped with the busy signaland camp-Qfl control unit (2241! KTU).

Note: When the 6A system it equipped withthe ce.mp-on feature, a camped-()n call will not

cut {hrough until all station b u ~ y circuits arenotmal.

(q) Add-on conferencing as described 1n 2.03.

2.05 The two-talking link arrangement (l'ig. 4)

provides for:

(a) A selector and a pr imary talking link asdescribed in 2.04 plus the addition of a

secondary talking link. This enables one sys tem

to carry on two simultaneous and independentconversations. Whenever the secondary link isfree, a call on the primary link is automaticallytransferred to it, thereby freeing the primary

link for another call. A slight click is heard

during this transfer operation.

Page 5



SECTION 51 8-4 1 0-1 00

FLASHING

LAMPS

BUSY TONE

INTERRUPTED

RINGING

Page 6

r---

lB KTU32

ELEC

MEC H

FLASH

RING

TR O-

ANI CAL

, WINK,

, AND

OU TIM E

CIR CUlT

-

22 2A KT U --2-L IN K

BATTERY

FEED AND

9- STATION

SIGNALING

CIRCUIT

'----

~ 19B KTU,

20 9A KTU f..--- FLASHING

OR LAMPS

212A KTU

FLASHING f---+ BUSY

..____

CI RCUIT TONE

-

:,--

. .__

r--

' - - - -

I PER

223A KTU ADDITIONAL

3 - STATION 3 STATIONS

SI GNALING

CIRCUIT

I PE R

2178 KT U SYSTEM

CONFERENCE

TIME-OUT CIRCUIT

I PER

227B KTU 3 ST ATIONS

STATION

BUS Y

CIRCUIT

Fig. 4-Tw o-Link Arrangement

21 6A KTU

TR ANSFER

CIRCUIT

207C KTU

SELECTOR

CIRCUIT

I2'17B KTU

TOUCH-TONE

ADAPTER

CiR CUIT

1!17B K"f(J

PR'IS !!iET

CO NI'EftENC E

CIRCUIT

227B KTU

SINGLE LINE

ADD-ON

TRANSFERCIRCUIT

I PE R

TIONAL

DES

ADD I

9 co

I PESYS

I PE

RTEM

R

EMYS T

I PE

PRE

CO N ARR

R 2

SE T

FERENC E

ANGEMENTS

I PE

STA

R 3 CONTROL

TIONS

OR I GINATING ADD-ONFERENCINGON

229B KTU SINGLEI PE R CONTROL

TIONR MULTIPLE

LINE AD D-O N

TRANSFER

CIRCUI T

226B KTU

ADD-ON

CONFERENC E

CIRCUI T

224B KT U

BU SY TONE

AN DCA MP-ON

CONTROL

CIRCUIT

2278 KTU

RINGING

AND TONECON TROL

Cl RCUIT

225A KTU

LON G LINE

CIR CUIT

2278 KTU

AUXILIA RY

RELAYBUSY LAMP

CIRCUIT

227B KTU

AUXILIA RY

RELAY

LAM P FLASH

CI RCUIT

STA

OR I GINATING ADD-ON

FE RENCINGON

I PE R CO OR

PBX Ll NE TO

CONFERENCED E

t----TO KE Y TELEPHONE

SYSTEM

I PE~ R SYSTEM

DIAL TONE

BUSY TONE

RINGINGTONE----

/---+ ST ATION BUSY

I PE

EOUI

R SYSTEM

PPED WITH

TONE AND

RRUPTED

lNG

DIAL

INTE

RING

I PE R

PREMISEFF-

STA TION

f---+TO OF F- PREMISE

STATION

!PER SYSTEM

WHE NOVER 40

LAMPSUS Y

I PER SYSTEM

WH ESIMU

N OVER 20LTANEOUS

HI NG LAMPSLAS



(i) Ringing tone

(j ) Selective conferencing

(k) Station busy feature

(I) Off-premise stations1 per

(m) Add- on c o n f e r e n c i n ~ 2·03

(n) Busy tone to a calling station when thecalled station is busy on the secondary link.

(o) Preset conferencing as described in 2.04 withthe added feature of the calling station

receiving a busy signal when a station that is

part of the preset conference arrangement calledis busy on the secondary link. Busy tone would

be heard until the first called station answers.

(p) Camp-on when associated with a two-linksystem and using the 224A KTU (MD) has

two phases of operation.

(1) Camping on a busy system (both links inuse) as described in 2.04 with the camp-on

control circuit locking operated under controlof the secondary link. The release of thesecondary link and the transfer operationfreeing the primary link would allow the called

station to be signaled automatically. Had theprimary link released first, the camped-oncondition would have persisted until the

secondary link had released, even though alink is available.

(2) The second phase of operation allows a

calling station to camp on when a stationthat is busy on the secondary link is called.Under this condition the calling station receives

ISS 6, SECTION 518-41 0-1 00

the busy tone and then reserves the intercom

system until the secondary link releases.

(q) Camp-on when associated with a two-linsystem and using the 224B KTU permit

the camp-on circuit to cut through when eithe

the primary or the secondary link become

available and the called station is idle.

Note: When the 6A system is equipped wit

station busy circuits, a camped-on call will nocut through until all station busy circuits ar

normal.

APPLICA l iON

2.06 Used in conjunction with CO or PBX lincircuits normally connected to lA, lAl, o

1A2 Key Telephone Systems or lOOA, lOlA, or B

or 102A Key Equipment.

ORDERING GUIDE

2.07 Unit, Telephone, Key __

Note: Order required units per Table A.

2.08 A two-talking link 6A Key Telephone System

is available in packaged form. For informatio

see Section 518-210-402.

ASSOCIATED APPARATUS

2.09 Power Supply

(a) The 6A Key Telephone System is designeto operate from a 20- to 26-volt de source

Since associated installations of other keequipment or key systems may operate at

somewhat lower value, 14 to 26 volts, it mabe necessary to replace the existing power supplor use an independent supply for the 6A system

equipment.

(b) The J86731A, List 4 (101G) power plant mabe used as an independent power supplfor any size and arrangement of the 6A KeTelephone System with the following limitations

• No load other than the 6A is placed on thpower plant.

• 20-volt talk terminals are used only fobattery designated A.

Page



SECTION 518-4 10-1 00

• 20-volt signal te rminals are used only for

battery designated B.

• 18 -volt ac terminals, audible and /or visual

si gnals, do not exceed 1.4 amperes .

• 10- volt ac terminals operate a m aximum ofseventy -two 51A la m ps, current drain not

to exceed 2.8 amperes .

When 10- and 18-volt ac taps are used

on the power plant, th e maximum

to tal current drain shal l not exceed

1.4 amperes.

• 105-volt ±terminals o pera te s imultaneously

one to e ight high-im pedance r ingers w ithou t

capacitors or one or tw o high-impedance

ringe rs w ith capacitors (one to three if 70

to 110 volts or one to five if 60 to 110 volts

is permit ted ).

• I f circuit failure occurs due to low line

voltage, move the p r imary tap to 111 volts.

(c) The following power plan ts have a capacity

large enough to be used as a common power

plant for combined sta t ion systems:

• J86471B, List 1 (101J)

• 19- o r 20-type

• 29- or 30-type

(d) ~ n r ingers are used as audible signals, a

separate pow er source supplying 105 volt s

20 cy cles must be provided when using the 101J

power plant. The 20- and 30-type pow er plants

include a 30-cycle ringing supply.

Note: W h e n us ing the 30-cycle supply ,

off-premise sta t ions must not be equ ipped wi th

intermediate t r ansmiss ion or toll ringing

repeat in g fa cilities.

(e) For power supp ly arrang e m e n ts , refer to

Section 167-400-180.

Page 8

(f) W hen centra l office, building, or local battery

is supplied, fuse as follows:

• One 2-amp fuse for talking battery designated

A.

• One 2-a m p f u se for signaling batterydesignated B.

• On e 2-amp fuse p er maximum of 36 signal

lamps.

• One 2-am p fuse for de audible signal supply.

Note: When th e sam e de source is used for

talking and audible signal operation a noise

suppression capacitor, such as the 23A KTU,

should be installed across the battery supply.

2.10 Appara tus m ountings, cabinets, and relay

racks for mounting key telephone units of a

6A system are as follows:

(a) A pparatus M ountings

• 16-type

• 26-type

(b) Cabinets

• 11 and 18 p late

• 26 plate

• 45 plate

• Floor-supported

(c) Relay Rack s

• Wall

• Floor-supported



ISS 6, SECTION 518-41 0-1 00

TABLE A

KEY TELEPHONE UNITS

USE PANEL WIDTH

KTUQUANTITY REQUIRED SEL· SINGLE · TWO-

FI G .

CODECIRCUITS

7/16- INCH NO.ONLY L IN K LIN K INCHE S

MODU LES

ARR ARR ARR

207C Selector 1 pe r system • :=:

• 5 -7 /32 12 5

21 5A 3-stat ion signaling 1 per 3 additional sta tions • 3-2 9/32 9 6

216A Transfer 1 pe r additional 9 codes • • 3-1/32 7 7

Preset conference control 1 pe r 2 conference arr • • •217B 3-15 /3 2 8 8

Conference time-ou t 1 pe r system • •22 2A Batt ery feed and 9-station

signaling1 pe r sy stem • 23 49 9

223A 3-station signal ing 1 per 3 additional sta tions • 5-2/32 13 10

224 B Busy signal and camp-on co n - 1 pe r sys tem •t •trol

3-15/3 2 8 11 225A Long line 1 pe r off-p rem is e station • • • 5 12

226 B Add-on conference contro l 1 pe r CO or PBX li ne to • • • 3-15 /3 2 8 13

be conferenced ---1 per sy stem equipped

Ringing and tone control with dial tone an d in ter- • • upted ringing

1 per 3 control st ations

Single li n e add-on transfer each originating 1 add-on • •conference l in e

227B Au xil iary relay busy lamp 1 per syste m when over 40 • • •3-1/32 7 14

+ line busy lamps

Auxiliary relay lamp f lash 1 pe r sys tem when over 20

• •simultaneous flash inglamps

Sta tio n busy 1 per 3 st ations • • 228A Blank ap paratus pa nel assem- As required for bridging • • • 3 -1 5/3 2 8

bly purposes

22 9B Single or 1 per control stationMultiple line add-on transfer originating 1 to 7 add-on • • 3-1/16 7 15

conference l in es

Electromechanical f lash , wink, 1 pe r system for flashing232§ ring, and time-out, when lamps, busy tone, and

• • 3-15/32 8 16type equipped with KS 15 900 , interrupted ringingList 1 in ter rupter

234A Ba ttery feed , 9-station signal- 1 pe r system ing, selector, an d transfer • 23 49 17

24 7B TOUCH-TONE adapt er 1 per sy stem • • • 7-15/32 1 7 18--- 1-----19 B§ Flashing 1 pe r system fo r flashing • • Mounting detail pe r

lamps and busy tone lo ca l engineering

" Equivalent of on e of these units is included as part of the 23 4A KT U

t Supply only when camp-on, dial tone, ringin g tone, or st ation busy circui t i s fur nished

t Uni t consists of three identical relays. Some feature s li sted require one or two relays. Remaining relay(s) may b

utilized fo r othe r fea tures.

§The required interruptions may be fu rnished by an associated key telephone system.

Page



SECTION 518-41 0-1 00

(d) To determine the size of the mounting facility,

the following should be taken into consideration:

• Type 6A arrangement

• Number and size of key telephone unitsrequired

• Future requirements

• Mounting of power supply

• Whether 6A system to be mounted separatelyor combined in same facility with associatedkey system.

(e) Refer to Section 463-140-100 for identification

of the mounting facilities.

Page 10

SElSD69286·01

Fig. 5-207C KTU, Selector Circuit

A

3 - STASI G

CKTS

Fig. 6-215A KTU, Signaling Circuit, Single-Talking

Link

Fig. 7-216A KTU, Transfer Circuit



ISS 6, SECTION 518-41 0-1 00

Fig. 8-2178 KTU, Preset Conference Control Circuit

9-STA SIG CKTS

COMMON

EQU IPMENT

Fig. 9- 222A KTU, Battery Supply an d Signaling Circuit, Two-Talking Link

Page 1



SECTION 518-41 0-1 00

3-STA

SIG

CKTS

Fig. 10-223A KTU, Station Signali ng Circuit,

Two-Talking Link

Fig. 11-224 8 KTU, Busy Signal Camp-On Cont ro l

C ir cuit

Page 12

lONG liNE

s o - 6 9 2 8 6 ~ 1p

Fig. 12-225A KTU, Long Line Circuit

F. 13-2268 KTU, Add-On Conferencing Cont ro lg.

Circui t



Fig. 14-2278 KTU, Auxiliary Relay Circuit

ISS 6, SECTION 518-410-1 00

•

· ~229B KTU

Fig. 15-2298 KTU, Single or Multiple Line Add-O

Transfer Circuit

Fig. 16-2328 KTU, Electromechanical Flash, Wink,

Ring, and Time-Out Circuit

Page 1



SECTION 5 18-41 0-1 00

SELECTOR

CKT 9-STA SIG CKTS

COMMON

EQU IPMENT

Fig. 17-234A KTU, Battery Feed and Signaling (Single-Link) Selector and Transfer Circuit

Fig. 18-2478 KTU, TOUCH-TONE Adapter

Page 14

3. INSTALLATION

3.01 Before commencing the installation of a 6A

system arrangement observe the fo llowing:

• Determine from the service order and work

sheet the type arrangement and features

required by the customer .

• Select the key telephone units required byreferring to Table A.

• Select a suitable mounting faci lity .

• Select an adequate power supply.

3.02 A careful review of the immediate needs of

the 9u.stomer, together with a considerationfor his future rearrangements and requirements,

will be beneficial in determining the method ofinstallation. Since each installation will vary to a

degree because of individual requirements, they



should be arranged in a m anner that will permit

maximum flexibility under the particular circumstances.

3.03 The installation of apparatus, key telephone

units, keys, stat ion sets, and other i tems

common to general stat ion work is covered in the

section pertaining directly to each ite m .

Handling of key telephone units

sometimes results in damage to

wire-spring relays . Af te r mou nting,

visually inspect all wire-spring re lays

for the fol lowing:

• Improper po sition of conta ct springs

• Broken actuating cards

• Im proper position of actuating cards

3.04 C ertain features can be obtained by st rapping

between individual key telephone units. O th er

features require such leads as T, R, L, LG, S,

Sl, A an d AI, normally ass ociated with stat ion

apparatus. For ease of w iring both at the t ime of

original installatio n an d at the time of fu ture

ad ditions or rea r rangement s , i t is suggested that

su ch leads be brought ou t and terminate d at a

common c r o s s - c o n n e c t m ~ ooin t.

3.05 Plant series sections covering the 6A Key

Telephone Sys tem ar rangements are as

follows:

(a) Con nections

• 518-410-400-Selector Only

• 518-410-401-Single-Talking Link

ISS 6, SECTION 518-41 0-1 0

• 518-4 10-402-Two- Talking Link

(b) Maintenance

• 518-410-300-Selector Only

• 518-410-301-Single-Talkin g Link

• 518-410-302 -T wo-Talking Link

3.06 Information covering the 247A (MD) an

247B (TO UCH-TONE adapters) key telephon

units are covered in Sections 518-310-113 an

518-310-114, respectively.

3.07 For m ain tenance of the 204-type selecto

which is a part of the 207C or 234A KTU

refer to Sections 069-339-801 and 026-708-801.

3 .0 8 For deta iled operational informatio n refeto the following:

• CD- and SD-69286-In te rcommunicating Lin

Circuit

• CD- and SD -69288-Pane l Mounted Unit s

• CD- and SD-69294-Visual and Audible Signa

Circuits

• CD- and SD-69447-T OUCH- ' rO N E Adapte

Circuit (247A KTU )

• CD- and SD -69529-TOUCH -TONE A dapte

Circuit Type D2 (247B KTU )

Page 1

15 Pag



BELL SYST EM PRACTIC ES

Plan t Ser ie s

ADDENDUM 518-410-100PTI ssue C, M ay, 19 61

Pac if ic Tel

6A KEY TELEPH O NE SYSTEM

IDENTIFICATION

1.000 INTRODUCTION

• This addendum supp lem ents S ect ion 518-410-100. It is i s sued to change and

de le te portio ns of the section to conform

with ta r if fs f il ed in the Pacif ic Co.

• This addendum sha ll be re ta ined w it h

subsequent is sues of the section unless

re issued o r cance lle d .

• Mark the changed portions of th e sec -

tion with the c r o ss- re fe r en ce "See

Addendum ''.

2.000 CH ANG ES AND DELETIO NS

• D elete a ll in fo rmation wit hin the sec tion

tha t re fe rs to th e "Sin gle Talk ing Link"

arrangem ent.

• D elete a ll "Se lector O nly" in fo rmation

tha t refe rs to S ignal Key Station Se lec -

tion.

• Change th e maximum number of sta tion

codes used on th e "Se lec tor Only "

arrangemen t from 36 12._ 40,

@)The Pacifi c Teleph on e and Telegra ph Company, 1960

Page

1 Pag

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518-410-100_I6 - 6A Key Telephone System Identification & Installation

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