1A1/71361/1

OUTGOING SUPERVISORY RELAY SET WITH METERING OVER JUNCTION AND DOUBLE UNIT ACCESS

AY Side

BX side

ITEM CIRCUIT REFERENCE DESCRIPTION QTY

051 MC,DD,B,CD,AA,HR,DR,

H,BC,LR,MP,LF Relay P.O No.25/4 013 7200 Ohm

052 BB,LN,LA,DS,XM,YM,DC Relay P.O No.25/3 007 2350 Ohm

053 RA,RB Relay P.O No.25/5 002

054 DA,DB Relay P.O No.25/9 002

055 DE Relay P.O No.25/10 001

056 IA Relay P.O No.25/12 001 345 Ohm

057 A Relay P.O No.25/11 001

058 BG Relay P.O No.25/2 001 15k ohm

059 UA Connector P.O No.215B

060 UB,UC Connector P.O No.215B

061 TPA-TPC Connector P.O No.207D

DESCRIPTION: * = or equivalent

SOURCE: Blank = Rate Book

4. HISTORY OF DOCUMENTATION.

4.1 Unit 1 Documentation.

701676/S AT 71361 MOD WORKS

ISSUE DATE ISSUE DATE SHEET SPEC

02 03/71 0 07/72

2A 10/72 EC

SPECIFICATION T7136l.PTL

PAGE 03

QTY SOURCE

013

007

002

001

8AAMk2 001

16AA Mk2 002

20/20A 003

DIAGRAM NOTES AT 71361

1. GENERAL

The relay set is used for outgoing trunk traffic only. Where the Supervisory is seized during the inter-train pause following the dialling of the 'trunk' digit, and subsequent digits are repeated directly via the relay set to the junction, no connection to the Register is required. Where the Supervisory is 'Primary route' it has Register-switch connection.

The double-unit-access facility enables each unit of a double-unit exchange to gain access to the Supervisory.

The block diagram on page 2 shows the relay set with its associated

equipment.

Typical Associated Diagrams:

C Switch (5 x 10)

Call Control

Supervisory Relay Set Selector

C-Switch Selector

Supervisory Pulse Distribution Circuit

COS Amplifiers

FACILITY SCHEDULE

Provision is made for:

(1) Interconnecting a C Switch, a Register Switch, and a 2-wire junction.~

(2) Extending a third wire to the junction MDF for the purpose of busying

or testing the state of the Supervisory.

(3) Monitoring the 2-wire junction for disconnection or reversal while the Supervisory is idle, and busying the Supervisory out of service when the junction is faulty.

(4) Indicating to a Supervisory Selector, upon interrogation by Call Control, that the Supervisory is free.

{5) Marking the C-Switch outlet {and, if Register connection is required, the Register switch outlet) when the Supervisory is selected for connection to a subscriber.

(6) A Negative-battery signal to be extended to a test point when the relay set is in use.

(7) Receiving the caller's class of service (X or Y).

(8) Receiving a class-of-connection signal. (Ie Supervisory or Register control.)

(9) The following facilities on calls with 'Supervisory control' class of connection, (ie connection to the controlling Register is not required):

(i) the caller's loop to be connected directly to the speech bridge.
(ii) holding the switched path and the caller's K relay as a result of (i), thus checking the line pair.
(iii) dialled digits to be repeated directly from the caller's line.

(10) The following facilities on calls with a 'Register Control' class of

connection:

(i)the caller's loop to be forwarded to the Register via the Register Switch.
(ii) holding the switched path and the caller's K relay under the control of the Register.
(iii) the forward loop and the regeneration of the keyed digits to be under the control of the Register.
(iv)the Supervisory to be held in such a manner that an immediate release can be effected whilst under the control of the Register.
(v) transferring to 'Supervisory Control' on receipt of a signal from the Register (during the decisive inter-train pause or at the end of digit regeneration).

(11) A metallic loop to be forwarded to the junction while a digit is being repeated or regenerated. (Note: Two-stage drop-back is not fitted, but space is available.)

(12) A transformer-type speech bridge.

(13) Positive-battery metering to be applied each time a reversal of the junction polarity occurs, a check being made that the first reversal persists for at least 50 ms before the first meter pulse is applied.

Provision is made for ensuring that only one meter pulse results from each MOJ (metering over junction) signal.

(14) The Supervisory to be prevented from releasing while a meter pulse is being applied.

(15) The Supervisory to be force-released and busied against further calls should be fault cause a permanent metering signal to be applied.

(16) The potential to the subscriber's line to be reversed when metering commences and maintained until the relay set is released. (Ie no 'clear' supervision.)

(17) Guarding against further calls for a minimum period of 800 ms after the junction loop is disconnected (when the Supervisory is released), in order that the Main-Exchange equipment has time to restore to normal.

(18) Lighting an ALARM lamp and giving a Deferred alarm under the control

of the exchange-alar.m key should:

(i) relay BG release owing to a junction fault.
(ii) a permanent metering condition be applied to the P wire.

(19) Connection of a terminating impedance across the junction pair whilst the Supervisory is free.

(20) Call trace.

(21) Traffic recording.

( 22) Working with:

(i) a junction-loop resistance of up to 2000 ohms (plus the resistance of the bridge equipment). The minimum acceptance leakage resistance is 50 kohms.
(ii) a subscriber's loop resistance of 1.3 kohms (including telephone instrument). The minimum acceptance leakage resistance is 50 kohms.

(23) A call to continue in the absence of the caller's class-of-service signal but, where phased metering is used, without metering.

3. CIRCUIT DESCRIPTION

3. 1 Outgoing Trunk Route is not Primary

3.1.1 Introduction

Since this Supervisory will not be connected except by Router

action, no register connection is required {assuming there are no keysending

subscribers connected to the exchange). After the subscriber has dialled

the 'trunk' digit on either the 0/G (local) or the 0/E Supervisory Relay

Set, Call Control interrogates 0/G (trunk-call) Supervisory Relay Sets by

extending a negative-battery signal on the STD(A)/STD(E) leads of the

0/G Trunk Supervisory Relay Sets. This causes transistor VT1 to switch on.

Negative battery is present on the base of transistor VT12 if the Supervisory

is free. Thus, when transistor VT1 switches on, transistor VT12 also switches

on and earths lead C to the C-Switch Selector. The C-Switch Selector

selects a C Switch with at least one free 0/G Trunk Supervisory Relay Set

connected to it. When this selection is made, negative battery is extended

on the S(A)/S(B) leads to the Supervisory Rel~ Sets associated with that

particular C Switch, causing transistor VT13 to switch on and hence operating

relay STD in all the free 0/G Trunk Supervisory Relay Sets in the group

associated with this C Switch.

The operation of relays STD extends the SS and MK leads to the

Supervisory Selector. The B-Switch Selector now determines a free path

to the selected C Switch. When this is completed, it enables the

Supervisory Selector to select a particular, free 0/G Trunk Supervisory

Relay set.

3.1.2 Circuit Operation: Setting up a Call

Contacts not mentioned are either spare or ineffective at that stage.

Relays HR and BG are normally operated.

With the Supervisory Relay Set free ie negative potential on the

P wires, the negative 'interrogating' potential on the ST.D{A)/STD(B)

from Route-Relays 1, gives rise to a negative potential on lead

S(A)/S(B) from the C-Switch Selector. Relay STD operates.

Relay HR releasing,

HR1 releases relay BG (normally operated)

Relay BG releasing,

BG1 operates relay LF.

Relay LF operating,

LF1 maintains the busy condition initiated by LA4.

The Supervisory is now ready to receive dialled information. During the first dial pulse, relay A releases.

3.1.3 The Called Party Answers

When the called party answers, the polarity on the junction is reversed at the remote exchange, and relay DE operates.

T.he reversed-line connection to the calling subscriber remains until the call is cleared.

When the Z-phase pulse arrives, it operates relay DA. (Note: theZ-pulse is used in preference to the X-pulse to reduce the metering-sequence time to less than one second. This is necessar.y to cater for high-rate metering-over-junction signals which can occur at intervals as little as one second.)

(b) Assume the junction-polarity reversal from the Main exchange ends before the completion of the X-phase pulse. Relay DE releases.

All contacts are ineffective.

The metering circuit now waits for further junction-polarity

reversals, and responds to them as described above.

In both of the sequences only one meter pulse results from a reversal

of the junction-polarity, and the meter pulse is of the correct duration.

3.1.4 Cleardown

There is no 'junction clear' detection; only the clearance by the caller is detected. The clearing sequence depends on whether the caller clears after or before the called line answers.

3.1.4(a) Assume Caller Clears After the Called Line has Answered

Relay A Releases

3.1.4 (b) Assume Caller Clears Before the Called Line Answers

The following relays are operated. A, AA, B, BB, BC, LA, LF, XM (or YM), LN.

When the caller clears, relay A releases.

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