# US 2013/0278271 A1 · Ground Monitor

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- Number: US 2013/0278271 A1
- Document ID: US20130278271A1
- Status: Published application
- Kind: A1
- Application number: 13/921,234
- Filed: 2013-06-19
- Published: 2013-10-24
- Earliest claimed: 2010-06-03
- Assignees: Lear Corporation
- Applicants: Lear Corporation
- Inventors: David A. Hein; Aftab Ali Khan
- Web page: https://patentgrep.com/patent/US20130278271A1

## CPC

- B60L 53/14: Conductive energy transfer
- B60L 3/0023: {Detecting, eliminating, remedying or compensating for drive train abnormalities, e.g. failures within the drive train}
- G01R 19/145: Indicating the presence of current or voltage
- G01R 27/18: Measuring resistance to earth {, i.e. line to ground}
- G01R 27/20: Measuring earth resistance; Measuring contact resistance, {e.g.} of earth connections, e.g. plates
- G01R 31/50: Testing of electric apparatus, lines, cables or components for short-circuits, continuity, leakage current or incorrect line connections (testing of sparking plugs H01T13/58)
- G01R 31/52: Testing for short-circuits, leakage current or ground faults
- Y02T 10/70: Energy storage systems for electromobility, e.g. batteries
- Y02T 10/7072: Electromobility specific charging systems or methods for batteries, ultracapacitors, supercapacitors or double-layer capacitors
- Y02T 90/12: Electric charging stations
- Y02T 90/14: Plug-in electric vehicles
- B60L: PROPULSION OF ELECTRICALLY-PROPELLED VEHICLES (arrangements or mounting of electrical propulsion units or of plural diverse prime-movers for mutual or common propulsion in vehicles B60K1/00, B60K6/20; arrangements or mounting of electrical gearing in vehicles B60K17/12, B60K17/14; preventing wheel slip by reducing power in rail vehicles B61C15/08; dynamo-electric machines H02K; control or regulation of electric motors H02P); SUPPLYING ELECTRIC POWER FOR AUXILIARY EQUIPMENT OF ELECTRICALLY-PROPELLED VEHICLES (electric coupling devices combined with mechanical couplings of vehicles B60D1/64; electric heating for vehicles B60H1/00); ELECTRODYNAMIC BRAKE SYSTEMS FOR VEHICLES IN GENERAL (control or regulation of electric motors H02P); MAGNETIC SUSPENSION OR LEVITATION FOR VEHICLES; MONITORING OPERATING VARIABLES OF ELECTRICALLY-PROPELLED VEHICLES; ELECTRIC SAFETY DEVICES FOR ELECTRICALLY-PROPELLED VEHICLES
- G01R: MEASURING ELECTRIC VARIABLES; MEASURING MAGNETIC VARIABLES (indicating correct tuning of resonant circuits H03J3/12)
- Y02T: CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION

## Abstract

A ground monitor is disclosed. The ground monitor may be configured to conduct a ground continuity test based on a determined ground resistance. The ground monitor may be operable to determine the ground resistance as a function of a voltage differential detected during application of a test current.

## Claims

### Claim at position 1

1-9. (canceled)

### Claim 10

A ground monitor being operably coupled to a three-pronged outlet having a hot plug, a neutral plug, and a ground plug of an AC power network to detect a ground resistance of the network based on a voltage differential between the neutral plug and the ground plug of the outlet, the ground monitor comprising:
a signal generator operable to apply a test current to the neutral plug at a first frequency, wherein the hot plug of the outlet receives a current flowing therethrough at a second frequency and the first frequency is different from the second frequency;
a filter being operable to remove signals having the second frequency and to output a filtered signal; and
a voltage sensor operable to measure a voltage differential between the neutral and ground plugs based on the filtered signal, the voltage differential representing the ground resistance during application of the test current.

### Claim 11 (depends on 10)

The ground monitor of claim 10 further comprising a frequency sensor operable to sense the second frequency of the current flowing to the hot plug and a controller operable with the frequency sensor to select the first frequency of the test current to be different from the second frequency.

### Claim 12 (depends on 11)

The ground monitor of claim 11 wherein the controller is further operable in a frequency test mode during which the test current is applied at a plurality of frequencies and to select the first frequency to be the one of the plurality of frequencies resulting in a highest quality measurement of the voltage differential.

### Claim 13 (depends on 12)

The ground monitor of claim 12 wherein the controller, during the frequency test mode, being further operable to also vary an amplitude of the test current for each of the plurality of frequencies, the controller being further operable to detect the varying amplitudes of the test current when determining the highest quality measurement.

### Claim 14 (depends on 13)

The ground monitor of claim 13 wherein the controller being further operable to determine the voltage variation induced at each of the varying amplitudes and selecting the highest quality measurement to correspond with the one of the plurality of frequencies where the voltage variations substantially correlates with the varying amplitudes.

### Claim 15 (depends on 10)

The ground monitor of claim 10 wherein the signal generator continuously applies the test current while the terminals are connected to the neutral and ground plugs.

### Claim 16 (depends on 10)

The ground monitor of claim 10 wherein the signal generator applies the test current in moments in which the current flowing through the hot plug is at a zero-crossing.

### Claim at position 9

17-20. (canceled)