Voltage measurement

• US 9,151,818 B2
• Filed: 11/08/2012
• Issued: 10/06/2015
• Est. Priority Date: 11/08/2011
• Status: Active Grant

• Current Assignee: Analog Devices International Unlimited Company (Analog Devices, Inc.)
• Original Assignee: Analog Devices Global Unlimited Company (Analog Devices, Inc.)
• Inventors: Hurwitz, Jonathan Ephraim David, Danesh, Seyed Amir Ali
• Primary Examiner(s): NGUYEN, HOAI AN D
• Application Number:
  US13/672,236
• Publication Number:
  US 20130113507A1
• Time in Patent Office: 1,062 Days
• Field of Search: 324/713, 324/691, 324/649, 324/600, 324/522, 324/98, 324/76.11
• US Class Current: 1/1
• CPC Class Codes: G01R 15/04 Voltage dividers
• CPC Class Codes: G01R 19/0084 measuring voltage only all subgroups of G01R19/00 take precedence
• CPC Class Codes: G01R 19/02 Measuring effective values, i.e. root-mean-square values
• CPC Class Codes: G01R 21/133 by using digital technique
• CPC Class Codes: G01R 21/14 Compensating for temperature change
• CPC Class Codes: G01R 35/04 of instruments for measuring time integral of power or current

Abstract

A voltage measurement apparatus is provided that includes: a potential attenuator configured to be electrically connected between first and second conductors, which are electrically coupled to a source, wherein the potential attenuator includes a first impedance and a reference impedance arrangement in series with each other, wherein the reference impedance arrangement has an electrical characteristic that can be changed in a known fashion; and further including a processing arrangement configured to acquire at least one signal from the reference impedance arrangement, the at least one signal reflecting change of the electrical characteristic in the known fashion; and to determine a voltage between the first and second conductors in dependence on the fashion in which the electrical characteristic is changed being known and the at least one signal.

Claims

1. Voltage measurement apparatus comprising:

a potential attenuator configured to be electrically connected between first and second conductors that are coupled to receive a line frequency signal, the potential attenuator comprising a first impedance and a reference impedance arrangement in series with each other, the reference impedance arrangement including a second impedance having an electrical characteristic which is adapted to change in a known fashion; and

including a first, offset voltage circuit, configured to provide a modulated offset signal that modulates the received line frequency signal at the second impedance, which is operative to apply an offset between the first and second conductors; and

a processing arrangement configured to acquire the received line frequency signal and the modulated offset signal from the reference impedance arrangement, the acquired signals reflecting change of the electrical characteristic in the known fashion; and

to determine a voltage between the first and second conductors in dependence on the fashion in which the electrical characteristic is changed being known and the acquired signals.

2. Voltage measurement apparatus according to claim 1 in which the processing arrangement is configured to determine an impedance of the first impedance in dependence on the fashion in which electrical characteristic is changed being known and the acquired signals.

3. Voltage measurement apparatus according to claim 2 in which the processing arrangement is further configured:

to determine an attenuation factor in dependence on the determined impedance of the first impedance; and

to determine the voltage between the first and second conductors by applying the attenuation factor to a signal acquired by the processing arrangement.

4. Voltage measurement apparatus according to claim 2 in which the processing arrangement is configured to compare a change in impedance of the first impedance from one determination to another with a threshold value.

5. Voltage measurement apparatus according to claim 1 in which the offset voltage circuit which is operative to apply a compensation signal to an acquired signal to cancel an effect of the offset voltage applied before acquisition.

6. Voltage measurement apparatus according to claim 1 in which the reference impedance arrangement is operative to apply at least one offset voltage between the second impedance and one of the first and second conductors.

7. Voltage measurement apparatus according to claim 1 in which the potential attenuator is configured such that the reference impedance arrangement is operative to apply plural offset voltages between the first and second conductors, the plural offset voltages defining a waveform of one of discrete form and continuous form.

8. Voltage measurement apparatus according to claim 1 further comprising a second potential attenuator configured to be electrically connected between the first and second conductors, the second potential attenuator comprising a first impedance and a reference impedance arrangement in series with each other, the reference impedance arrangement having an electrical characteristic which is changeable in a known fashion, the processing arrangement being responsive to the second potential attenuator.

9. Voltage measurement apparatus according to claim 8 in which the voltage measurement apparatus is configured such that the first and second potential attenuators are operative to change their respective electrical characteristic in different known fashions.

10. Voltage measurement apparatus according to claim 8 in which the processing arrangement is operative to subtract signals acquired from one of the first and second potential attenuators from signals acquired from the other of the first and second potential attenuators.

11. Voltage measurement apparatus according to claim 8 in which the processing apparatus is operative to correlate signals acquired from the first and second potential attenuators with each other to thereby align the signals with each other.

12. Voltage measurement apparatus according to claim 1 configured to determine at least one of an ac voltage between the first and second conductors and a dc voltage between the first and second conductors.

13. Voltage measuring apparatus comprising plural voltage measurement apparatus according to claim 1, each of the plural voltage measurement apparatus being configured to measure line voltage between a different pair of wires of the electricity supply.

14. A method of measuring voltage by way of a potential attenuator electrically connected between first and second conductors that are coupled to receive a line frequency signal, the potential attenuator comprising a first impedance and a reference impedance arrangement in series with each other, the reference impedance arrangement including a second impedance having an electrical characteristic which is adapted to change in a known fashion, the method comprising:

providing a modulated offset signal that modulates the received line frequency signal at the second impedance so as to apply an offset between the first and second conductors;

acquiring the received line frequency signal and the modulated offset signal from the reference impedance arrangement, the acquired signals reflecting change of the electrical characteristic in the known fashion; and

determining a voltage between the first and second conductors in dependence on the fashion in which the electrical characteristic is changed being known and the acquired signals.