# US 9,007,069 B2 · Method of testing a spur short circuit protection system and diagnostic device for performing the method > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 9,007,069 B2 - Document ID: US9007069B2 - Status: Granted - Kind: B2 - Application number: 13/576,834 - Filed: 2011-02-04 - Published: 2012-11-29 - Granted: 2015-04-14 - Earliest claimed: 2010-02-05 - Assignees: Pepperl + Fuchs GmbH - Applicants: Renato Kitchener; Gunther Rogoll - Inventors: Renato Kitchener; Gunther Rogoll - Web page: https://patentgrep.com/patent/US9007069B2 ## CPC - H02H 9/008: {Intrinsically safe circuits} - G01R 31/2827: {Testing of electronic protection circuits (testing switches G01R31/327; checking alarm systems G08B29/00; self test of summation current transformers H02H3/335)} - H02H 3/044: {Checking correct functioning of protective arrangements, e.g. by simulating a fault (for differential current circuit breakers H02H3/335)} - H02H 3/05: with means for increasing reliability, e.g. redundancy arrangements {(for logic circuits H03K19/003)} - H02H: EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS (indicating or signalling undesired working conditions G01R, e.g. G01R31/00, G08B; locating faults along lines G01R31/08; emergency protective devices H01H) - G01R: MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES (indicating correct tuning of resonant circuits H03J3/12) ## Abstract A method of testing a short circuit protection system applied to a spur of an electric circuit. The short circuit protection system has a current limiting means which applies a current limit to the spur if the current thereon exceeds a trip level. The electric circuit has a power supply and an isolation means adapted to fully or partially isolate the power supply from the electric circuit if the current thereon exceeds a power supply trip level for longer than a deadband period. The method includes applying a test current demand to the short circuit protection system which has a current and duration sufficient for the spur current trip level but a current insufficient to exceed the power supply trip level and/or a duration insufficient to exceed the deadband period, and detecting if the current limiting means applies the current limit or not during the test current demand. ## Claims ### Claim 1 A method of testing a short circuit protection system applied to a spur of an electric circuit, in which the short circuit protection system comprises a current limiting device comprising a series semiconductor element and a current sense/drive circuit, which current limiting device applies a current limit to said spur if the current thereon exceeds a spur current trip level, in which the electric circuit comprises a power supply and an active monitoring and isolating system which fully or partially isolates the power supply from the electric circuit if the current thereon exceeds a power supply trip level for longer than a deadband period, in which said method comprises the following steps: i) applying a test current demand to said short circuit protection system which has a current and duration sufficient for said spur current trip level to be exceeded, but a current insufficient for said power supply trip level to be exceeded and/or a duration insufficient to exceed said deadband period, ii) detecting if the current limiting device applies said current limit or not during said test current demand. ### Claim 2 (depends on 1) A method according to claim 1, in which said spur comprises one or more load devices, and in which said test current demand is insufficient in duration to cause device brown out of said one or more load devices. ### Claim 3 (depends on 2) A method according to claim 2 in which said electric circuit is a communications electric circuit carrying data telegrams, and in which said test current demand is insufficient in duration to interrupt more than one data telegram carried on said electric circuit. ### Claim 4 (depends on 1) A method according to claim 1 in which the test current demand is applied during step i) for a duration of between 10 μs and 500 μs. ### Claim 5 (depends on 4) A method according to claim 4 in which the test current demand is applied during step i) for a duration of between 25 μs and 50 μs. ### Claim 6 (depends on 1) A method according to claim 1 in which step ii) is performed after a current overshoot allowance delay period. ### Claim 7 (depends on 6) A method according to claim 6 in which said current overshoot allowance delay period has a duration of between 10 μs and 20 μs. ### Claim 8 (depends on 6) A method according to claim 6 in which the test current demand is applied to the short circuit protection system in step i) in a square wave form. ### Claim 9 (depends on 6) A method according to claim 6 which comprises the further step: iii) in the event that the current limit is applied, measuring said current limit. ### Claim 10 (depends on 1) A method according to claim 1 in which the test current demand is applied to the short circuit protection system in step i) in a ramped fashion. ### Claim 11 (depends on 10) A method according to claim 10 in which the test current demand is ramped up over a period of between 10 μs and 20 μs. ### Claim 12 (depends on 1) A method according to claim 1 which comprises the further step: iv) in the event that the current limit is applied, measuring the time taken for it to be applied by the current limiting means. ### Claim 13 (depends on 1) A method according to claim 1 which comprises the further step: v) after the test current demand has ended, not applying a further test current demand for a pre-determined delay period. ### Claim 14 (depends on 1) A method according to claim 1 in which the electric circuit is a Fieldbus electric circuit confirming to the IEC 61158 standard, and in which said test current demand applied in step i) is adapted to operate within the electrical characteristics of Fieldbus. ### Claim 15 (depends on 1) A method according to claim 1 in which said spur comprises one or more load devices, and in which step i) is performed by electronically reducing said spur current trip level to below the quiescent current of the spur. ### Claim 16 A diagnostic device for testing a short circuit protection system applied to a spur of an electric circuit, wherein the short circuit protection system comprises a current limiting device comprising a series semiconductor and a current sense/drive circuit which current limiting device applies a current limit to a connection to terminals of said spur if the current thereon exceeds a spur current trip level, and wherein the electric circuit comprises a power supply and an active monitoring and isolation system which fully or partially isolates the power supply from the electric circuit if the current thereon exceeds a power supply trip level for longer than a deadband period, the diagnostic device comprising: i) a current demand application device for applying a test current demand to said short circuit protection system which has a current and duration sufficient for said spur current trip level to be exceeded, but a current insufficient for said power supply trip level to be exceeded and/or a duration insufficient to exceed said deadband period; and ii) a detection device for detecting if the current limiting device applies said current limit or not during said test current demand. ### Claim 17 (depends on 16) A diagnostic device as claimed in claim 16 in which the diagnostic device further comprises a current measuring means which in the event that the current limit is applied, is adapted to measure said current limit. ### Claim 18 (depends on 17) A diagnostic device as claimed in claim 17 in which the diagnostic device further comprise a clock function adapted to measure the time taken for the current limit to be applied by the current limiting means. ### Claim 19 (depends on 16) A diagnostic device as claimed in claim 16 in which the diagnostic device further comprises an interface via which operational commands are receivable in use, and data gathered transmittable in use. ### Claim 20 (depends on 16) A diagnostic device as claimed in claim 16 in which the diagnostic device is a discreet apparatus selectively connectable to said spur. ### Claim 21 (depends on 20) A diagnostic device as claimed in claim 20 in which the diagnostic device is provided with its own power supply independent of the power supplied to said spur. ### Claim 22 (depends on 20) A diagnostic device as claimed in claim 20 in which the diagnostic device is powered by the same power supplied to said spur. ### Claim 23 (depends on 22) A diagnostic device as claimed in claim 22 in which the diagnostic device comprises a reservoir capacity adapted to prevent device brown out of the diagnostic device when said current demand is applied in use. ### Claim 24 (depends on 16) A diagnostic device as claimed in claim 16 in which the diagnostic device is incorporated in a device coupler along with said short circuit protection system.