Circuit arrangement for testing the connecting lines of a switch or sensor

• US 4,862,091 A
• Filed: 07/20/1988
• Issued: 08/29/1989
• Est. Priority Date: 07/28/1987
• Status: Expired due to Fees

• Current Assignee: BMW AG (Bayerische Motoren Werke AG)
• Original Assignee: Bayerische Motoren Werke AG
• Inventors: Hillebrand, Helmut
• Primary Examiner(s): NOT, DEFINED
• Assistant Examiner(s): Miele, Anthony L.
• Application Number:
  US07/221,742
• Time in Patent Office: 405 Days
• Field of Search: 324/415, 324/537, 324/421, 324/550, 340/644, 340/52 H, 340/638, 280/735
• US Class Current: 324/415
• CPC Class Codes: B60R 21/0173 Diagnostic or recording means therefor
• CPC Class Codes: G01R 31/58 Testing of lines, cables or conductors testing of electric windings G01R31/72
• CPC Class Codes: H01H 9/167 Circuits for remote indication

Abstract

A circuit arrangement is disclosed for monitoring the connecting lines of a switch or sensor open in the normal condition, with a first ohmic resistance connected in series with the switch or sensor. That together with the switch or sensor and a second ohmic resistance connected in parallel to both forms a parallel circuit, whose first connecting line is connected to ground and whose second connecting line is connected, on the one hand, to a voltage supply by way of a third ohmic resistance and, on the other, with a voltage discriminator unit. The second ohmic resistance is adapted to be disconnected.

Claims

1. A circuit arrangement for monitoring the connecting lines of a switchable device open in the normal condition, comprising:

a first resistance means connected in series with said device;

a second resistance means connected in parallel with the first resistance means and the device to form a parallel circuit;

a first connecting line connecting said parallel circuit with ground potential;

a second connecting line connecting said parallel circuit to a voltage supply means by way of a third resistance means and to a voltage discriminator means;

a Zener diode in series with the second resistance and operable to disconnect the second resistance means; and

said voltage supply means including a first output voltage larger then the breakdown voltage of the Zener diode and a second output voltage smaller than the breakdown voltage of the Zener diode, and means for selecting the first or second output voltage.

2. A circuit arrangement according to claim 7, wherein said resistance means are ohmic resistances.

3. A circuit arrangement according to claim 7, wherein said device is one of switch or sensor.