GB2215562A

GB2215562A - Emergency power supply for telephone system

Info

Publication number: GB2215562A
Application number: GB8902222A
Authority: GB
Inventors: Benno Carolus; Guenter Koerner
Original assignee: Deutsche Telephonwerke und Kabelindustrie AG
Current assignee: Deutsche Telephonwerke und Kabelindustrie AG
Priority date: 1988-02-04
Filing date: 1989-02-01
Publication date: 1989-09-20
Anticipated expiration: 2009-02-01
Also published as: NL8900167A; PT89602B; BE1001445A3; DK44089D0; GB8902222D0; GR890100062A; DE3803710A1; IT1228171B; LU87426A1; FR2628275A1; PT89602A; ES2010124A6; DK44089A; IT8919276A0; IE890224L; GB2215562B

Description

1 -1- 2215562 i Circuit Arrangement for Telephone Terminal Stations The

invention relates to a circuit arrangement for telephone terminal stations which are connected by way of a network terminating unit to an integrated services digital communications network (ISDN).

For terminal stations which are connected to an integrated services telecommunications network (ISDN), there are given standardized interfaces.

Connected between an exchangeside interface, e.g. U interface, and a subscriber-side interface, S interface, also termed S-bus, there is a network terminating unit (NT) (Figure 1). The network terminating unit (NT) supplies the subscriber-side interface and a portion of the terminal stations, preferably the telephone terminal stations, with electrical energy. Further connected terminal stations such as, for example, teletex, telefax, data transmission, screen text stations etc. have their own voltage supplies. In the event of voltage failure it is to be ensured that a telephone terminal station is supplied with voltage from the exchange by way of the network terminating unit (NT) in order to obtain the basic function of telephony. In this connection, through the user of the exchange a maximum power consumption is prescribed for such a telephone terminal station during emergency operation.

According to the present there is provided a circuit arrangement for telephone terminal stations which are connected by way of a network terminating unit to an integrated services digital communications network (ISDN) and are supplied during normal operation with energy and to which there is available, in each case, a direct voltage transformer for the purpose of generating internal feed voltages, operable such that when there is failure of the voltage supply at the network terminating unit a telephone terminal station associated with this network terminating unit draws energy from an exchange, a central processor of the telephone terminal station registering a potential reversal at the supply and signal lines as a criterion o: the emergency operation, wherein the power consumption during emergency operation is determined by a highly resistive voltage divider at supply lines of the telephone terminal station, wherein with closed emergency current switches a series arrangement comprising a first transistor and a thyristor is connected between one supply line and a feed line to the direct voltage transformer, and wherein connected in parallel to this series arrangement there are a contact of a changeover switch and a second transistor for the firing control of the thyristor, and for the purpose of interrupting current flow between the supply line and feed line by blocking the thyristor the control electrode of the first transistor is connectable by way of a third transistor with a control signal input of the central processor.

An embodiment of the invention may provide a voltage supply for the emergency operation of the telephone terminal station not exceeding a given power consumption, e.g. typically 25 mw in the passive state.

For a bettei understanding of the present invention and to show how it may be put into effect, reference will now be made by way of example to the accompanying drawing in which:

Figure 1 shows the block circuit diagram of a telecommunications network as already described; and Figure 2 shows a portion of a circuit arrangement according to the invention of a telephone terminal station of Figure 1.

3- Figure 2 shows that a telephone terminal station, which is to operate during emergency operation, is equipped with additional switches (NS1, NS2). This is always only one station of the possible eight connected stations of an S-bus or a network terminating unit (NT).

During normal operation the telephone stations draw their supply from the network terminating unit (NT), in which case positive potential is applied to a supply line (1) and negative potential is applied to a supply line (2). When the telephone terminal stations are installed, switches (NT1, NT2 not shown) for the telephone terminal station provided for the emergency operation are closed. The supply potential is applied by way of the switches (NT1, NT2) to feed lines (3, 4) which lead to a direct voltage transformer. The direct voltage transformer serves to generate the supply voltages for the hardware of the telephone terminal station. The positive potential thereby is applied by way of a diode (G1) to the feed line (3), and the negative potential is applied by way of a diode (G2) to the feed line (4) in the active and in the passive state.

During emergency operation, all the terminal stations are switched off, apart from the telephone terminal station provided. As a criterion of the emergency operation,.for which in the passive state the power value of e.g. 25 mw may not be exceeded, there serves a potential reversal at the supply lines (1, 2).

The negative potential of the supply line (1) is then applied by way of diode (G3) to the feed line (4). The direct voltage transformer obtains no positive potential.

The positive potential is connected through only in the case of control from the passive state to the active state. This takes place with transmitting occupation or operation through switching of the changeover switch (GU), the control electrode of a thyristor (T) thus receiving positive potential and the thyristor (T).firing. By means of a first transistor (T1), the thyristor (T) and the switch (NS1), a current then flows to the feed line (3).

In the case of receiving occupation or operation, by means of the activation routine of the network terminating unit (NT) the static potential on the S-bus is replaced by a series of pulses and connected to the pulse input (7) through pulse emission of a bus-receiving module, the first pulse controlling a second transistor (T2) in a conducting manner and with that connecting the potential from the supply line (2) to the control electrode of the thyristor (T). As previously described, the thyristor (T) fires.

The same effect can also be achieved by means of an auxiliary pulse source, e.g. a stored charge in the telephone terminal station, or a generated voltage pulse, which reaches the point (6), for example, by way of a key actuation.

If the telephone terminal station is controlled from the active into the passive state, a signal from the central processor of the telephone terminal station reaches the control electrode of a third transistor (T3) by way of a control input (5) of the central processor of the telephone terminal station. The third transistor (T3) is controlled in a conducting manner and blocks the first transistor (T1).

As a result of the fall below the holding current of the thyristor (T) the latter is extinguished, whereby during emergency operation the potential is separated from the feed line (3). The remaining power consumption in the passive state during emergency Ii i k -5 operation is then exclusively determined by the highly resistive voltage divider (R1, R2).

There is proposed for telephone terminal stations (1 to 8) which are connected by way of a network terminating unit (NT) to an integrated services digital communications network, a circuit arrangement which when there is failure of the energy supply, during emergency operation controls the supply through the exchange in such a way that in the passive state the power consumption of the telephone terminal station is reduced to a minimum. To this purpose, the voltage for internal. users of the telephone terminal station is switched off and only switched on again in the active state, i.e. with transmitting or receiving occupation or operation.

i 1 -6- i I

Claims

CLAIMS:

1. Circuit arrangement for telephone terminal stations which are connected by way of a network terminating unit (NT) to an integrated services digital communications network (ISDN) and are supplied during normal operation with energy and to which there is available, in each case, a direct voltage transformer for the purpose of generating internal feed voltages, operable such that when there is failure of the voltage supply at the network terminating unit (NT) a telephone terminal station associated with this network terminating unit (NT) draws energy from an exchange, a central processor of the telephone terminal station registering a potential reversal at supply and signal lines as a criterion of the emergency operation, wherein the power consumption during emergency operation is determined by a highly resistive voltage divider (R1, R2) at supply lines (1, 2) of the telephone terminal station, wherein with closed emergency current switches (NS1, NS2) a series arrangement comprising a first transistor (T1) and a thyristor (T) is connected between one supply line (2) and a feed line (3) to the direct voltage transformer, and wherein connected in parallel to this series arrangement there are a contact of a changeover switch (GU) and a second transistor (T2) for the firing control of the thyristor (T), and for the purpose of interrupting current flow between the supply line (2) and feed line (3) by blocking the thyristor (T) the control electrode of the first transistor (T1) is connectable by way of a third transistor (T3) with a control signal input (5) of the central processor.

2. Circuit arrangement according to claim 1, wherein the changeover switch contact and the second transistor (T2) are coupled between the control electrode of the thyristor (T) and the one supply line (2).

3. Circuit arrangement according to claim 1 or 2, wherein the second transistor (T2) is controllable by way of a pulse input (7) through pulse emission of a bus-receiving module.

4, Circuit arrangement according to any preceding claim, wherein the second transistor (T2) is controllable by means of a pulse from a stored charge or by a generated voltage pulse.

5. A circuit arrangement according to claim 1 and substantially as'hereinbefore described with reference to the accompanying drawing.

Published 1989 atThePa;tent Office, State House, 6671 High HolbornLondonWClR4TP. Further copies maybe obtainedfrom The Patent Office. Sales Branch, St Mary Cray, Orpington, Kent BR5 3RD. Printed by Multiplex techniques ltd, St Mary Cray, Kent, Con. 1/87