GB2271243A

GB2271243A - Collecting data from hazardous environments via telephone

Info

Publication number: GB2271243A
Application number: GB9318409A
Authority: GB
Inventors: Robert Kent Clark
Original assignee: ADS Environmental Services Inc
Current assignee: ADS Environmental Services Inc
Priority date: 1992-10-05
Filing date: 1993-09-06
Publication date: 1994-04-06
Also published as: GB9318409D0; DE4331575A1

Abstract

A remote data-collecting system has a telephone access connection arrangement in which a telephone ring-responsive data-collection system 16, 18, 20 disposed, for example, in a sewer 12 is connected to a telephone service line 23 through a remote opto-isolator 21 in which a telephone ringing signal actuates a light-emitting diode (32 in fig 2) and a phototransistor (33 in fig 3) responds to light to provide a low-voltage ring signal to the data-recording system. The system effectively isolates the high voltage ringing signal from the potentially hazardous data collecting environment. <IMAGE>

Description

2271243 REMOTE DATA ACCESS TELEPHONE CONNECTION SYSTEM This invention

relates to remote data access telephone connection arrangements for use in accessing data recorded in hazardous environments in which high-voltage signals should be avoided.

In potentially explosive environments, such as sewers, for example, where explosive gases may accumulate, it is important to exclude high-voltage electrical signals which may generate a spark. Many conventional sewer flow monitoring systems, however, include a data-recording unit having a modem disposed within a sewer manhole which is connected to a conventional telephone service line. The modem is arranged to respond periodically to a telephone ring signal transmitted on the telephone service line to transmit data accumulated by the recording unit over the telephone line.

The telephone ringing signal provided on a telephone service line, however. generates a voltage whic'h can be as high as 130 volts RMS which could be sufficient to produce a spark capable of igniting sewer gases. Moreover, because the connections between a modem and conventional datarecording equipment of the type used to monitor sewer conditions require more than the standard five conductors used in a buried telephone line, it is inconvenient to move such a modem to a location remote from the sewer-monitoring equipment located in the manhole. On the other hand, providing an explosion-proof enclosure within the manhole or at an adjacent underground location in which the telephone service line and the modem can be connected would involve substantial construction and be quite expensive.

Accordingly, it is an object of the present invention to provide a remote data access telephone connection arrangement for connecting telephone service lines to data- recording units in potentially explosive environments which overcomes the above-mentioned disadvantages.

2 Another object of the invention is to provide a remote data access telephone connection arrangement which can easily and conveniently be used with conventional telephone lines.

These and other objects of the invention are attained by providing a telephone ring-responsive data-recording unit and an associated modem for coupling the data recording unit to a telephone line within a potentially explosive environment such as a sewer manhole, providing a ring signal isolator for isolating the telephone ring signal from the telephone service line and for producing a corresponding low-voltage output signal at a location remote from the potentially explosive environment,, and coupling the ring signal isolator and the telephone line to the data-recording unit and modem in the explosive environment. Further objects and advantages of the invention will be apparent from a reading of the following description in conjunction with the accompanying drawings, in which: 20 Fig. 1 is a schematic illustration showing the arrangement of a representative remote data access telephone connection according to the invention; and Fig. 2 is a schematic circuit diagram showing the circuit arrangement of a representative ring signal isolator for use in the remote data access telephone connection arrangement shown in Fig. 1.

In the typical remote data access telephone connection arrangement shown in Fig. 1, a f low detector 10 and a height detector 11 are disposed in a sewer line 12 to detect the liquid flow rate and the height of a liquid 13 flowing through the sewer line 12. To record this information, the detectors are connected by corresponding lines 14 and 15 to a data-recording unit 16 disposed in an adjacent manhole 17. The recording unit 16. which is powered by an adjacent low-voltage battery 18, is arranged to record the detected liquid level and flow rate periodically. for example, every 15 minutes.

3 In addition. the recording unit 16 is arranged in the usual manner to be responsive to a telephone ring signal received from a telephone line 19 through a modem 20 connected to the telephone line to reproduce and transmit the recorded data through the telephone line. The sewer line 12 and the manhole 17 may be subject to accumulation of potentially explosive gases and, to avoid possible ignition of such gases during operation of the system, the detectors 10 and 11 and the data recorder 16 are designed to operate at low voltages, for example less than 50 volts DC, provided by the low-voltage power source 18.

The ring signal normally received on a telephone line, however, may produce an AC voltage of as high as 130 volts RMS, which could be sufficient to ignite potentially explosive gases in the sewer and the manhole. To prevent this possibility and provide intrinsically safe recording and transmitting equipment within the manhole in accordance with the invention. the telephone line 19 leading from the manhole 17, which may, for example, be a conventional five- conductor buried telephone line, is connected to a ring signal isolator 21 disposed at a remote location such as in a conventional telephone line connection vault 22 or, alternatively, on a telephone pole. The isolator 21 is, in turn, connected to a telephone service line 23 leading to, for example, the local exchange of the telephone company.

The arrangement of a typical ring signal isolator 21 for use in the system shown in Fig. 1 is illustrated in detail in Fig. 2. In this case, the five-conductor line 19 includes two conductors 24 and 25 for transmitting data signals from the modem 20 in the recording unit 16, a ring- detect line 26, a ground line 27, and an off-hook line 28.

On the other side, the isolator 21 is connected to two conductors 29 and 30 in the telephone service line 23 leading to the telephone exchange, for example.

Within the isolator 21, a telephone service line ring signal received on the lines 29 and 30 is detected by a ring signal-detecting unit 31 so as to cause a light- 4 emitting diode 32 connected to the ring signal detector to be illuminated. An adjacent phototransistor 33 connected between the ground line 27 and the ring-detect line 26 responds to illumination from the light-emitting diode 32 to cause the recording unit 16 to initiate an off-hook signal on the line 28, closing a relay 34 to connect the audio signal lines 24 and 25 from the modem to the telephone service lines 29 and 30 through an isolating transformer 35 and capacitor 36. It will be understood that the relay 34 may be replaced by any conventional device for completing a connection in response to an electrical control signal, such as a solid state device or an optocoupler.

The isolating arrangement 21 isolates the equipment within the manhole 17 from the lines 29 and 30 so as to block any high-voltage signals on those lines but pass the audio data signals. The audio data signal transmitted by the modem on lines 24 and 25 may. for example. have an amplitude of less than one volt, while the' ring-detect signal produced by the phototransistor 33 and the off-hook signal on the line 28 may both be only about 5 volts. for example.

After transmission of the recorded information is complete, the off-hook signal is terminated, releasing the relay 34 or other connecting device and disconnecting the recording unit from the telephone service lines 29 and 30.

Thus, with this arrangement, a convenient telephone line remote data access connection to a recording unit in a sewer manhole is provided permitting transmission of a ring signal and data signals while blocking dangerously high voltage signals from the telephone line from reaching the manhole.

Claims

1. A remote data-collecting system for use in a potentially explosive environment to connect a telephone service line to-a data-collecting means located in the potentially explosive environment, the system including a low-voltage power supply means for location in the potentially explosive environment to supply power to the data-collecting means, isolating means for location remote from the potentially explosive environment to produce a low-voltage signal in response to a telephone ring signal, and connecting means for connecting the data-collecting means in the potentially explosive environment to the isolating means to permit a low-voltage signal produced by the isolating means in response to a ring signal to be applied to the data-collecting means and to permit signals produced by the data- collecting means to be transmitted to the telephone service line.

2. A system according to claim 1, wherein the isolating means includes light signal-generating means responsive to a telephone ring signal to produce a light signal, and photodetector means for producing a lowvoltage signal in response to a light signal produced by the lightgenerating means.

3. A system according to claim 2, wherein the light signal-generating means comprises a light-emitting diode and the photodetector means comprises a photodiode.

4. A system according to any of claims 1 to 3, wherein the datacollecting means is disposed in a sewer system and includes liquid flow and liquid level detecting means in a sewer and data-recording means with a low-voltage power supply disposed in a manhole for recording data from detectors at periodic intervals.

6

5. A system according to claim 4, wherein the isolating means is disposed in a telephone connection vault remote from the manhole.

6. A system according to claim 4, wherein the isolating means is disposed on a telephone pole.

7. A system according to claim 1, substantially as described with reference to the accompanying drawings. 10