The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Apr. 12, 1988
Filed:
May. 20, 1987
Matti Kahkipuro, Hyvinkaa, FI;
Harri Hakala, Hyvinkaa, FI;
Pekka Nummi, Nurmijarvi, FI;
Urpo Sten, Hyvinkaa, FI;
Kone Elevator GmbH, Baar, CH;
Abstract
A method of and apparatus for controlling a braking resistor, provided in a d.c. circuit of a frequency converter, by rectifying a mains voltage, by means of a first rectifier bridge connected to a three-phase mains supply, to form an actual value voltage; comparing said actual value voltage and a reference voltage; and operating a switch in series with the braking resistor to cause the latter to conduct when the comparison indicates that the actual value voltage is greater than the reference voltage. The reference voltage is formed from a rectified voltage obtained from the three-phase mains supply and rectified by a second rectifier bridge.