Earthed circuit for an electric railway car
AssigneeMitsubishi Denki Kabushiki Kaisha
InventorShigeru Koyama
Life of this patent
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Abstract
An earthed circuit for an electric railway car which is equipped with an electric circuit including an electrical apparatus for which a switching operation is performed by use of a power semiconductor device includes a first brush attached to one of the axles of the car for connecting a return circuit for the electric circuit to the ground and a second brush attached to the same axle to which the first brush is attached for connecting the car body and a box for holding the electrical apparatus to the ground. The noise current caused by the switching operation of the power semiconductor device can be effectively prevented from flowing into the rails on which the car is running.
Claims14
An electric railway car noise signal grounding circuit which reduces the amount of noise and switching transients that are impressed on rails over which said railway car runs, said noise signal grounding circuit for use with an electric railway car which includes a car body, a drive current circuit, power switching devices in said drive current circuit for controlling drive current and a return circuit connecting said power switching devices through a contact mechanism to said rails for conducting return current to said rails, said noise signal grounding circuit comprising:
- an electrical shield surrounding said power switching device;
- connector means electrically connected to said contact mechanism for making an electrical connection to said rails;
- and
- means for connecting said electrical shield to said connector means so that said electrical shield is electrically connected to said rails at the same physical point as said return circuit.
An earthed electric railway car electrical circuit which reduces the amount of noise and switching transients that are impressed on rails over which said railway car runs, said electrical circuit comprising:
- a drive current circuit;
- a traction motor;
- power switching devices in said drive current circuit for controlling drive current to said traction motor;
- a contact mechanism electrically contacting said rails for conducting return current from said traction motor to said rails;
- a electrical shield surrounding said power switching device;
- connector means electrically connected to said contact mechanism for making an electrical connection to said rails;
- and
- means for connecting said electrical shield to said connector means so that said electrical shield is electrically connected to said rails at the same physical points as said contact mechanism.
A method for reducing the amount of noise and switching transients that are impressed on rails over which an electric railway car runs, said electric railway car including a car body, a drive current circuit, power switching devices in said drive current circuit for controlling drive current, and a return circuit connecting said power switching devices through a contact mechanism to said rails for conducting return current to said rails, said method comprising the steps of:
- A. providing an electrical shield around said power switching devices, and
- B. connecting said electrical shield to said connector means so that said electrical shield is electrically connected to said rails at the same physical point as said return circuit.
Dependencies are inferred from the claim text.