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From page 18... ... 18 Developing the Guidebook for Detecting and Mitigating Low-Level DC Leakage and Fault Currents in Transit Systems A Research Plan This section of the Final Report consists of a summary of the problem being researched and the project objectives. Read the entire page →
From page 19... ... Developing the Guidebook for Detecting and Mitigating Low-Level DC Leakage and Fault Currents in Transit Systems 19 In Phase I, the research team conducted a literature survey of the existing technologies and standards for leakage current modeling and prediction in transit railway systems. The team developed a model and a simulation of the electric transit system to test the feasibility of the proposed injection method in determining the level of the leakage current. Read the entire page →
From page 20... ... 20 Guidebook for Detecting and Mitigating Low-Level DC Leakage and Fault Currents in Transit Systems iv) NFPA 130, Standard for Fixed Guideway Transit and Passenger Rail Systems The NFPA 130 covers life safety from fire and fire protection requirements for fixed guideway transit and passenger rail systems, including, but not limited to, stations, train ways, emergency ventilation systems, vehicles, emergency procedures, communications, and control systems. Read the entire page →
From page 21... ... Developing the Guidebook for Detecting and Mitigating Low-Level DC Leakage and Fault Currents in Transit Systems 21 DC Systems and Insulation Failure Mechanisms. Due to the lack of previous work about leakage currents in the positive side and failure in railway systems, the research team reviewed the literature on DC power line transmission systems and their failure mechanisms. Read the entire page →
From page 22... ... 22 Guidebook for Detecting and Mitigating Low-Level DC Leakage and Fault Currents in Transit Systems where Ihighest and γ are expressed in amp, and by the equivalent salt deposit density (ESDD) , in mg/cm2, respectively. Read the entire page →
From page 23... ... Developing the Guidebook for Detecting and Mitigating Low-Level DC Leakage and Fault Currents in Transit Systems 23 iii) Differential Protection The main principle in the differential protection approach is that the input and output currents of the protected zone are equal, except in the case of internal faults (the algebraic sum of all currents in the protection zone is ideally zero in all cases except for internal faults) Read the entire page →
From page 24... ... 24 Guidebook for Detecting and Mitigating Low-Level DC Leakage and Fault Currents in Transit Systems into the railway power line to cancel the flow of the high frequency injected signal. The new method requires no direct connections to the overhead power line. Read the entire page →
From page 25... ... Developing the Guidebook for Detecting and Mitigating Low-Level DC Leakage and Fault Currents in Transit Systems 25 an approximate model can be obtained. As explained in (18) Read the entire page →
From page 26... ... 26 Guidebook for Detecting and Mitigating Low-Level DC Leakage and Fault Currents in Transit Systems 1,000 A 0.08 0.04/km /km 80 km 1,100 V 4 km Table 3. Parameters values used in the simulation. Read the entire page →
From page 27... ... Developing the Guidebook for Detecting and Mitigating Low-Level DC Leakage and Fault Currents in Transit Systems 27 Insulators have two metallic ends to suspend the conductor to the tower. There is a nonconductive material between the two ends to keep a high level of insulation between conductor and ground. Read the entire page →
From page 28... ... Figure 8. Insulator test setup for high frequency impedance measurement. Read the entire page →
From page 29... ... Developing the Guidebook for Detecting and Mitigating Low-Level DC Leakage and Fault Currents in Transit Systems 29 Task 4: Comparison Metrics Development Through Simulations As in Task 3, the research team focused on developing the new sensors referred to previously. In this task, the team developed a condition assessment to distinguish between good and bad components that could be manifested in their high frequency behaviors. Read the entire page →
From page 30... ... 30 Guidebook for Detecting and Mitigating Low-Level DC Leakage and Fault Currents in Transit Systems as the transit vehicle moves through the railway. Notice that the leakage current through the contaminated insulator is almost twice that of the healthy insulator. Read the entire page →
From page 31... ... Developing the Guidebook for Detecting and Mitigating Low-Level DC Leakage and Fault Currents in Transit Systems 31 through the bus. The impedance of the feeder, at high frequency, is monitored by tracking the injected signal. Read the entire page →
From page 32... ... 32 Guidebook for Detecting and Mitigating Low-Level DC Leakage and Fault Currents in Transit Systems Figure 16. Ratio between the DC current in healthy and fault conditions. Read the entire page →
From page 33... ... Developing the Guidebook for Detecting and Mitigating Low-Level DC Leakage and Fault Currents in Transit Systems 33 Task 5: RF Emission-Based Technology The second approach is based on evaluating RF emissions from the deteriorated components of the electric railway system. The technology developed by Exacter, Inc., provides mobile surveys of the electric grid evaluating EMI (electro-magnetic interference) Read the entire page →
From page 34... ... 34 Guidebook for Detecting and Mitigating Low-Level DC Leakage and Fault Currents in Transit Systems the sensor in capturing the arc was evaluated. The DC algorithms were installed in the Exacter Technology Sensor and confirmed to function properly. Read the entire page →
From page 35... ... Developing the Guidebook for Detecting and Mitigating Low-Level DC Leakage and Fault Currents in Transit Systems 35 short bursts of arcing when the pantograph momentarily separates from the wires. This causes a strong broadband frequency burst, which lasts briefly in the time domain. Read the entire page →
From page 36... ... 36 Guidebook for Detecting and Mitigating Low-Level DC Leakage and Fault Currents in Transit Systems Figure 22. Example of train arcing data from the RF emission sensor. Read the entire page →
From page 37... ... Developing the Guidebook for Detecting and Mitigating Low-Level DC Leakage and Fault Currents in Transit Systems 37 Figure 24. Example of AC fault data from the RF Emission Sensor. Read the entire page →
From page 38... ... 38 Guidebook for Detecting and Mitigating Low-Level DC Leakage and Fault Currents in Transit Systems The results show the locations of points of electric deterioration on the railways electric infrastructure. The team noticed consistent background RF noise mixed in with the electric infrastructure survey data. Read the entire page →
From page 39... ... Developing the Guidebook for Detecting and Mitigating Low-Level DC Leakage and Fault Currents in Transit Systems 39 The core of the high frequency transformer must be designed so it does not get saturated by the DC current in the power line. This can be done by increasing the size of the core, choosing a material with high permeability (such as a nanocrystalline material) Read the entire page →
From page 40... ... 40 Guidebook for Detecting and Mitigating Low-Level DC Leakage and Fault Currents in Transit Systems The next step is to determine the current needed by the system. This current is the sum of the current that reaches the secondary, the current dissipated in the winding, and the current needed to develop the flux in the core (especially in the air gap) Read the entire page →
From page 41... ... Developing the Guidebook for Detecting and Mitigating Low-Level DC Leakage and Fault Currents in Transit Systems 41 leaving the potentiometer circuit open. Then, the signal goes through a high pass filter to remove any low frequency signal and process only the high frequency signal. Read the entire page →
From page 42... ... 42 Guidebook for Detecting and Mitigating Low-Level DC Leakage and Fault Currents in Transit Systems The resulting output is a DC level signal that contains all the needed information. This signal then goes directly to the microprocessor. Read the entire page →
From page 43... ... Developing the Guidebook for Detecting and Mitigating Low-Level DC Leakage and Fault Currents in Transit Systems 43 to retrieve the amplitude and phase information from the measured signal, while it is assumed that the frequency of operation is already known. Multiplying these two signals results in the demodulated signal d(t) Read the entire page →
From page 44... ... 44 Guidebook for Detecting and Mitigating Low-Level DC Leakage and Fault Currents in Transit Systems and ( ) Read the entire page →
From page 45... ... Developing the Guidebook for Detecting and Mitigating Low-Level DC Leakage and Fault Currents in Transit Systems 45 output from this sensor can serve as a direct tripping signal for the circuit breaker or simply as a warning signal for the maintenance team. The complete system is shown in Figure 32. Read the entire page →
From page 46... ... 46 Guidebook for Detecting and Mitigating Low-Level DC Leakage and Fault Currents in Transit Systems C.6 Preliminary Field Tests at GCRTA The research team had several meetings with GCRTA. The team underwent GCRTA's Rail Operations Rule Book training certification program. Read the entire page →
From page 47... ... Developing the Guidebook for Detecting and Mitigating Low-Level DC Leakage and Fault Currents in Transit Systems 47 Substation power supplies and the control panels at the GCRTA Brookpark facility. Impedance measurements of the line from the midsection with direct connection to the ground line. Read the entire page →
From page 48... ... 48 Guidebook for Detecting and Mitigating Low-Level DC Leakage and Fault Currents in Transit Systems Fault implementation in the mid-section of the line. Data logging of the sensor measurements through wireless communication networks. Read the entire page →
From page 49... ... Developing the Guidebook for Detecting and Mitigating Low-Level DC Leakage and Fault Currents in Transit Systems 49 Case A (healthy system) In Case A, the system is healthy, and there are no faults or leakage currents in the system, as shown in Figure 36. Read the entire page →
From page 50... ... 50 Guidebook for Detecting and Mitigating Low-Level DC Leakage and Fault Currents in Transit Systems Case E (faults on both sides) In Case E, the overhead line was shorted on both sides of the sensor, as shown in Figure 41. Read the entire page →
From page 51... ... Developing the Guidebook for Detecting and Mitigating Low-Level DC Leakage and Fault Currents in Transit Systems 51 6. Roman, M., R.R. Read the entire page →
From page 53... ... Abbreviations and acronyms used without definitions in TRB publications: A4A Airlines for America AAAE American Association of Airport Executives AASHO American Association of State Highway Officials AASHTO American Association of State Highway and Transportation Officials ACI–NA Airports Council International–North America ACRP Airport Cooperative Research Program ADA Americans with Disabilities Act APTA American Public Transportation Association ASCE American Society of Civil Engineers ASME American Society of Mechanical Engineers ASTM American Society for Testing and Materials ATA American Trucking Associations CTAA Community Transportation Association of America CTBSSP Commercial Truck and Bus Safety Synthesis Program DHS Department of Homeland Security DOE Department of Energy EPA Environmental Protection Agency FAA Federal Aviation Administration FAST Fixing America's Surface Transportation Act (2015) FHWA Federal Highway Administration FMCSA Federal Motor Carrier Safety Administration FRA Federal Railroad Administration FTA Federal Transit Administration HMCRP Hazardous Materials Cooperative Research Program IEEE Institute of Electrical and Electronics Engineers ISTEA Intermodal Surface Transportation Efficiency Act of 1991 ITE Institute of Transportation Engineers MAP-21 Moving Ahead for Progress in the 21st Century Act (2012) Read the entire page →
From page 54... ... TRA N SPO RTATIO N RESEA RCH BO A RD 500 Fifth Street, N W W ashington, D C 20001 A D D RESS SERV ICE REQ U ESTED ISBN 978-0-309-48164-9 9 7 8 0 3 0 9 4 8 1 6 4 9 9 0 0 0 0 Read the entire page →

From page 18...

... 18 Developing the Guidebook for Detecting and Mitigating Low-Level DC Leakage and Fault Currents in Transit Systems A Research Plan This section of the Final Report consists of a summary of the problem being researched and the project objectives.