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A braking chopper is an magnetical switch that limits the DC bus voltage by switching the braking energy to a resistor where the braking energy is converted to heat. Braking choppers are automatically activated when the actual DC bus voltage exceeds a specified level depending on the nominal voltage of the variable-frequency drive
Schematic of an inverter using a vibrator as a chopper. In electronics, a chopper circuit is any of numerous types of electronic switching devices and circuits used in power control and signal applications. A chopper is a device that converts fixed DC input to a variable DC output voltage directly.
The use of both braking systems at the same time is called blended braking. Li-ion batteries have also been used to store energy for use in bringing trains to a complete halt. [1] Although blended braking combines both dynamic and air braking, the resulting braking force is designed to be the same as the air brakes on their own provide.
A DC injection brake system can be used as an alternative or addition to a friction brake system. DC injection brakes only require a small module located with the other motor switchgear and/or drivers, mounted in a remote and convenient location, whereas a friction brake must be mounted somewhere on the rotating system.
When the brake pipe and car components are charged with air, the brakes release. When the engineer needs to make a brake application, control valves in the locomotive reduce the brake pipe pressure. As the brake pipe pressure is reduced, the service portions on each car divert air from their reservoirs to their brake cylinders.
Front brakes are generally much more effective than rear brakes: roughly two thirds of stopping power comes from the front brake—mainly as a result of weight transfer being much more pronounced compared to longer or lower vehicles, because of the motorcycle's short wheelbase relative to its center of mass height. This can result in brake dive.
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Kuhlmann, J. H., Design of Electrical Apparatus, 3rd edition; New York: John Wiley & Sons, Inc., 512 pages, 1950. <Note, this book does not consider superconducting machines. However, it provides excellent detailed design information that could be used when designing a superconducting machine.>