METER No. 19

3 Internal
Issue 3, Oct 77

Meter No. 19/ ...

The Meter No. l9/..., when connected to a subscriber's line, will indicate to the subscriber the number of charge units which have been registered on his meter in the exchange when subscriber trunk dialling is in operation. It will step with the exchange meter.

There are two types of the meter, No. 19/FRA (right) and No. 19/SSS (above and lower right). They are interchangeable. In each meter the units' hand and the resettable trip hand move one division on the scale for each operating pulse. The hundreds' hand moves progressively over its scale, each division of which represents a complete revolution of the units' hand.

The trip hand can be returned to zero without affecting the operation of the meter by pressing the reset button or lever.

meter19s.jpg (13180 bytes)A total of 9999 units can be recorded and the trip hand will register up to 99 units.

The meter is operated by pulses of 50 Hz current which are injected into the line at the exchange. The pulses, nominally at 45 V and with a duration of 200-300 milliseconds, are impressed on the line longitudinally to earth. The meter is series tuned to 50 Hz and gives adequate rejection of 17 and 25 Hz ringing frequencies. At PBXS, etc, 50 Hz ringing should not be used where subscribers' private meters are provided (see Q0005).

The meters are intended for use with DELs (including Extension Plans), cordless switchboards, PBX extensions, House Exchange Systems, and in exceptional cases one party of a Shared Service Line.

The first models will be supplied complete with Cord, Inst, No. 3/105L, Grebe, 54 in, for the Meter No. 19/SSS and Cord, Inst, No. 3/62AB, Grebe, 54 in, for the Meter No. 19/FRA. The cord connection screws in the meter are located behind the removable panel in the base. Access into the mechanism is not provided.

1. DELs (Including Extension Plans) The cord will normally be connected to the instrument terminal block, red and green to line, white to earth. Where the meter is required remote from the telephone, extension wiring to a separate block, Terminal, No. 52A will be needed.

An earth connection should be provided from the terminal block. Where a protective earth or a signalling earth exists, this may be used.

Because of the high impedance of the meter, the resistance of the earth connection is not critical.

The pulses might be audible on some Extension Plan installations because of unbalance to earth in the wiring between stations. If this wiring is proved to be at fault, it must be separated from all other wiring and earth's and run in a non-metallic sheathed cable.

Plans 105 and 107 Meter No. 19 at an Internal Extension Where the meter is required to function on "Extension to Exchange" calls only, it will be necessary to provide an Auxiliary Gravity Switch Springset in the extension telephone. This switch (e.g. No. 19 B-1) should be connected between two spare terminals' in order to interrupt the meter operating earth when the extension telephone hand-set is on the rest.

2. Cordless Switchboards and PMBX Extensions See TI C3 E5001.

3. PABX Extensions and Manual Switchboard of PABX No. 1 See TI C3 F2500.

4. House Exchange Systems See TIs C3 C3034 and C3 C3036.

The location of the meter should be agreed with the subscriber. The subscriber may wish to have the meter by the side of the telephone for his own use, or remote from the telephone if the primary purpose is to check the charge incurred by a casual user. The ideal arrangement for the latter would be to have the meter visible but inaccessible to the telephone user.

Normally the meter will be free standing, but two blind tapped holes (4BA, 0.44 in deep) are provided in the base for screw fixing.

19/FRA   1/16 in   2 Washers No. 4 BA, Small, Oxidised, Lacquered
19/SSS   1/8 in   3 Washers No. 4 BA, Large, Oxidised, Lacquered

If a wall mounting is required by the subscriber, the meter should be screwed to a bracket which can be made locally; a suitable design is shown in Drg 91089.

When screw fixing is used, care should be taken that the tapped bushes are pulled against something solid (such as a distance piece) between the base of the meter and the baseboard. Never the less the feet should remain in contact with the baseboard thus preventing strain due to rocking caused, for instance, by operation of the reset mechanism.

Where two or three meters axe to be located together, they should be of the same type suitably mounted and labelled for identification (see TIs C3 E5001 and F2500 for guidance).

To test the operation of a subscriber's private meter, a call should be dialled to a test number in the local exchange or a nearby exchange; this should cause the meter to register one unit when inverted ring tone is connected. In director exchanges it is necessary to use a test number circuit returning a permanent loop (i.e. that previously known as a "multi-metering test number"). The test call may be repeated a few times if considered necessary to confirm the result. The number of test calls made should be carefully noted and advised to the Maintenance Control so that the subscriber's account may be suitably credited. Calls on which the private meter fails to operate must not be held (for example, for tracing in the exchange) because of the uncertainty regarding registration which may be continuing periodically on the exchange meter.

Attempts must not be made to gain access to any component or to any part of the mechanism. Only a change of cord is permissible. Any meter which fails to work satisfactorily should be returned to the Supplies Dept using the normal procedure for the return of faulty items.

Because of the delicate mechanisms in these meters they should be handled with care at all times and transported only in the packing boxes in which they are supplied.

The presence of the meter does not affect the normal line test condition.

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Last revised: December 14, 2010