Contactor health monitor circuit and method

Patent metadata

Field	Value
Publication number	US-9267974-B2
Application number	US-201213655144-A
Country	US
Kind code	B2
Filing date	Oct 18, 2012
Priority date	Apr 19, 2010
Publication date	Feb 23, 2016
Grant date	Feb 23, 2016

Abstract

In one possible implementation, a method is provided for determining contactor health including measuring a differential voltage between a first utility line voltage and a second utility line voltage on a primary side of a contactor and on a secondary side of the contactor. The measuring is performed with both an unloaded current and with a load current. The unloaded and loaded measurements are performed at the primary side and the secondary side, and are made with the contactor closed. It includes determining a difference between a secondary unloaded voltage and a secondary loaded voltage and subtracting a difference between a primary unloaded voltage and a primary loaded voltage to provide a contactor voltage drop. The contactor resistance is determined by dividing the contactor voltage drop by the loaded current.

First claim

What is claimed is:

1. A method for determining contactor health, the method comprising:
a) measuring a differential voltage between a first utility line voltage and a second utility line voltage on a primary side of a contactor and on a secondary side of the contactor;
b) wherein the measuring is performed with both an unloaded current and with a load current;
c) wherein both the unloaded and loaded measurements at the primary side and the secondary side are made with the contactor closed;
d) determining a difference between a secondary unloaded voltage and a secondary loaded voltage and subtracting a difference between a primary unloaded voltage and a primary loaded voltage to provide a contactor voltage drop; and
e) determining the contactor resistance by dividing the contactor voltage drop by the loaded current.

2. The method of claim 1 , further comprising repeating the measuring, the determining the difference, and the determining the contactor resistance, and further comprising using a plurality of samples of the contactor resistance to determine an averaged contactor resistance.

Assignees

• Flack Albert
• Aerovironment Inc

Inventors

• Flack Albert

Classifications

• G01R31/68

  Testing of releasable connections, e.g. of terminals mounted on a printed circuit board · CPC title

• G01R27/205 Primary

  Measuring contact resistance of connections, e.g. of earth connections · CPC title

• H01R43/002

  Maintenance of line connectors, e.g. cleaning · CPC title

• G01R1/30

  Structural combination of electric measuring instruments with basic electronic circuits, e.g. with amplifier · CPC title

• G01R31/66

  Testing of connections, e.g. of plugs or non-disconnectable joints (testing for incorrect line connections G01R31/55) · CPC title