Importance

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Abstract

An elevator may include an elevator motor driving at least one elevator car in a hoisting path, which elevator motor is driven via a frequency converter controlled by a control device of the elevator. The frequency converter includes a rectifier bridge and an inverter bridge and a DC link in-between. The elevator further includes at least one elevator brake acting on a brake element rotating with the rotor of the elevator motor, which elevator brake is driven via a brake drive which is connected to the DC link of the frequency converter an comprises a DC/DC converter having its primary side connected to the DC link and its secondary side connected to a brake circuit comprising at least one brake coil of the elevator brake and at least one rectifying element. In the primary side of the DC/DC converter, a first semiconductor switch is connected which is controlled by the control device of the elevator. In the brake circuit a second semiconductor switch is connected which is also controlled by the control device of the elevator, whereby an earth fault indication circuit is connected between the brake circuit and earth. The earth fault indication circuit includes an transmitting part of an opto-coupler, which opto-coupler has its sensor part connected to an earth fault transmission circuit connected to the control device of the elevator. The control device is configured to control the first and/or second semiconductor switch depending on the signal of the earth fault transmission circuit.

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First Claim