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Similar to Characteristics Of Eddy Current Braking
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Characteristics Of Eddy Current Braking
- 1. Karl W. Berger, P.E. Vice President DCM, Inc. Centreville, VA ASME Rail Transportation Division Fall Technical Conference Roanoke, VA October 12, 2010
- 2. High Speed Truck with ECB DCM, Inc. ASME RTD Fall Technical Conference 2010 2
- 3. Conventional EM Track Brake DCM, Inc. ASME RTD Fall Technical Conference 2010 3
- 4. Why is there a need for a new braking system? Long standing goal of improving safety through better braking. HSR requires high brake capacity. Dynamic braking has high speed limitations. Friction braking: Maintenance of shoes and disks. Creates noise and dust. Reduce reliance on rail adhesion. DCM, Inc. ASME RTD Fall Technical Conference 2010 4
- 5. George Westinghouse asked Commodore Vanderbilt to invest in air brakes. If I understand you, young man, you propose to stop a railroad train with wind. I have no time to listen to such nonsense. ___!?! DCM, Inc. ASME RTD Fall Technical Conference 2010 5
- 6. Basic principle DCM, Inc. ASME RTD Fall Technical Conference 2010 6
- 7. ECB Forces per Truckset 100 90 80 Force (kN) 70 60 FB 50 Fa 40 30 20 10 0 0 50 100 150 200 250 300 Train Speed (km/h) DCM, Inc. ASME RTD Fall Technical Conference 2010 7
- 8. Knorr Bremse EWB154R DCM, Inc. ASME RTD Fall Technical Conference 2010 8
- 9. Brake Blending 600 500 Total Brake Effort Eddy Current Brake Braking effort per trainset (kN) Dynamic Brake 400 Friction Brake 300 200 100 0 0 50 100 150 200 250 300 350 Speed (km/h) DCM, Inc. ASME RTD Fall Technical Conference 2010 9
- 10. ECB Experience ICE3 trainset has 4 trailer cars in 8-car set equipped with ECB. Authorized on Cologne-Frankfurt and Nuremberg-Ingolstadt lines and on LGV Est from Baudrecourt to Vaires Permitted only on ballastless, slab track to resist uplift and thermal buckling. Under study in Japan, Korea, and China. DCM, Inc. ASME RTD Fall Technical Conference 2010 10
- 11. Required Changes EMC certification with signal systems, axle counters, crossing gate detectors, hot wheel detectors Replacement of magnetic covers on wayside equipment enclosures. Requires coordination of headways with rail heating. DCM, Inc. ASME RTD Fall Technical Conference 2010 11
- 12. Regulatory perspective European Rail Infrastructure Managers position on use of Eddy Current Brakes: The unrestricted use of eddy current brakes cannot be allowed. Infrastructure must be adapted to the use of ECB. Physical clearance must exist between track structure and the ECB brake head. EMC with track mounted and lineside equipment must be addressed. Track resistance to longitudinal, vertical and lateral forces must be considered. DCM, Inc. ASME RTD Fall Technical Conference 2010 12
Editor's Notes
- Here is a Siemens SF500 truck equipped with Knorr Bremse eddy current brakes. The brakes consist of electromagnets with alternating poles. The magnets are carried in a frame that transmits the retarding force to the truck through torque bars. The magnets are held about 6mm above top-of-rail when in the operating position. This truck also carries three disk brakes per axle. The truck is rated for 350km/h (220mph).
- ECB is not the same as electromagnetic track brakes as used on Light Rail Vehicles. Conventional track brakes rely on friction between the magnetic pole pieces and the rail head. There is no controllability other than APPLIED or RELEASED.
- Noise reduction is a significant driver for ECB
- George Westinghouse proposes air brakes to Commodore Vanderbilt (president of the New York Central) in 1868.
- The magnets create two forces: the braking force FB that opposes the motion of the train, and Fa an attractive force between the magnet and rail head. The motion of the magnet relative to the rail creates eddy currents in the rail that dissipate energy in the electrical resistance of the steel.
- This is the uncontrolled characteristic of ECB. The braking force is relatively constant for speeds down to 50 km/h. (about 20kN = 4,500lbf) Fa exceeds FB below 180km/h and rises rapidly as speed drops. The attractive force adds to the axle loading and must be limited below about 100km/h.
- In the RELEASE position the bellows are pressurized and lift the magnets away from the rail. In APPLY the springs are vented to allow the frame to drop onto stops in the axle box supports. As the train speed decreases the bellows are repressurized to compensate for deflection in the magnet frame as the attractive force increases. This maintains the air gap at a constant width of about 7 mm.
- This is a representative curve for an 8-car trainset. Total braking effort results in deceleration of 0.65 m/s2 (1.45 mphps) at 330 km/h rising to a maximum of 1.1 m/s2 (2.5 mphps) from about 180 km/h down to standstill. ECB provides about half the effort above 200 km/h. ECD is tapered off below 100 km/h to prevent track uplift.