EP0087307A2
Expired / Lapsed
EP
⏱️ 0.0 years remaining
Temperature monitoring systems
Assignee: Dreamland Electrical Appliances PLC
•
Filing: 1983-02-21
•
Granted: —
•
Expires: 2003-02-21
Abstract
Abstract A temperature monitoring system, useful for example for detecting fires, comprises a cable (10) having at least two conductors (16, 18) separated by elongate temperature-sensitive means. The shunt impedance (or a component thereof, for example the resistance Rs) between the conductors (16, 18) is monitored to monitor the cable temperature. The impedance (or a component thereof, such as the resistance) between the ends of a series circuit comprising at least one of the conductors (18, 20) is also monitored. The latter impedance (or component) varies in accordance with the temperatures of the associated conductor or conductors (18, 20) and thus indicates the ambient temperature.
Inventors
- 👤 Roy Frederick Nailor
- 👤 Paul Owen Sanders
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-01 08:44
CPC Classifications
G; G08; G08B; G08B17/00; G08B17/06
Claims Analysis
Total Claims: 12
Claim 1
Independent Claim
109 words
A temperature monitoring system comprising: a cable arrangement having at least two conductors, two at least of said conductors (16, 18) being separated by elongate temperature-sensitive means; and means for monitoring the shunt impedance (or a component (Rs) thereof) between the conductors (16, 18) separated by the temperature-sensitive means; the system being characterised by means for monitoring the impedance (or a component thereof) between the ends of a series circuit comprising at least one of the conductors (18, 20) of the cable arrangement, said impedance (or component) varying in accordance with the temperature of said at least one conductor (18, 20) and thus being indicative of the ambient temperature.
Claim 2
Dependent Claim
109 words
A temperature monitoring system comprising: a cable arrangement having at least two conductors, two at least of said conductors (16, 18) being separated by elongate temperature-sensitive means; and means for monitoring the shunt impedance (or a component (Rs) thereof) between the conductors (16, 18) separated by the temperature-sensitive means; the system being characterised by means for monitoring the impedance (or a component thereof) between the ends of a series circuit comprising at least one of the conductors (18, 20) of the cable arrangement, said impedance (or component) varying in accordance with the temperature of said at least one conductor (18, 20) and thus being indicative of the ambient temperature.
Claim 3
Dependent Claim
30 words
A system according to claim 1, wherein the second-mentioned means for monitoring is operative to monitor - wholly or predominantly - the resistance between the ends of the series circuit.
Claim 4
Dependent Claim
71 words
A system- according to claim 1 or claim 2, wherein the first-mentioned means for monitoring (+V, R, 60) is operative to indicate a fire or other overheat situation and ' the second-mentioned means for monitoring (40, 62) is operative separately to indicate when the ambient temperature exceeds a value less than a value necessary to cause the first-mentioned means for monitoring (+V, R, 60) to indicate a fire or other overheat.
Claim 5
Dependent Claim
169 words
A system according to claim 1, wherein the elongate temperature-sensitive means has an impedance that varies with temperature, the system comprising: means (+V, R) for generating a first signal representing said shunt impedance (or a component thereof) between the conductors (16, 18) separated by the temperature-sensitive means and thus varying with local or general variations in the temperature of the cable arrangement; means (40) for generating a second signal representing said impedance (or a component thereof) measured between the ends of said series circuit comprising at least one of the conductors (18, 20) of the cable arrangement; means (34) responsive to a predetermined relationship between the first signal and a reference value to provide an output signal indicating that the temperature of at least part of the cable arrangement has exceeded a predetermined value; and compensation means (44) responsive to the value of the second signal to alter said reference value in a sense at least partially to compensate for changes in the ambient temperature of the cable arrangement.
Claim 6
Dependent Claim
22 words
A system according to claim 4, wherein the second signal is wholly or predominantly representative of the resistance of the series circuit.
Claim 7
Dependent Claim
42 words
A system according to claim 4 or claim 5, wherein the compensation means (44) is operative to vary the relationship between the second signal and the reference value in a sense complementary to that in which the first signal varies with temperature.
Claim 8
Dependent Claim
35 words
A system according to claim 6, wherein the first signal varies substantially antilogarithmically with the temperature and the compensation means (44) provides a generally logarithmic transfer function between the second signal and the reference value.
Claim 9
Independent Claim
33 words
A system according to any one of claims 4 to 7, wherein the compensation means (44) is operative not to alter the reference value if the second signal exceeds a predetermined limit value.
Claim 10
Independent Claim
40 words
A system according to any one of claims 4 to 8, wherein the compensation means is operative to alter the reference value between a plurality of predetermined discrete values in response to variation in the value of the second signal.
Claim 11
Independent Claim
166 words
A system according to any one of claims 4 to 9, wherein the means for generating the first signal comprises energisation means (+V, R) operative to send d.c. current through a circuit network including the temperature sensitive means, thereby to generate the first signal in the form of a d.c. signal representative of the resistance (Rs) of the temperature-sensitive means, and switch means (50) operative periodically to reverse the connection of the temperature-sensitive means into the circuit network and therefore to reverse the direction of current flow through the temperature-sensitive means, the frequency of operation of the switch means being sufficiently low that, after a change in the first signal that will take place upon each said reversal due to reactance of the temperature-sensitive means, the first signal will revert substantially to a steady value before the next reversal, and wherein the means (34) providing said output signal is responsive to said predetermined relationship between said steady value of the first signal and the reference value.
Claim 12
Independent Claim
53 words
A system according to any one of the preceding claims, wherein said series circuit comprises a pair of conductors (18, 20) that are connected together or integral with one another at one end of the cable arrangement and are connected to the compensation means (44) at the other end of the cable arrangement.
References Cited (Backward Citations)
No citation records indexed.
USPTO Annuity & Maintenance Windows
Maintenance schedule is calculated for granted US utility patents.