Actuator position indicator using actuator inductance

Patent metadata

Field	Value
Publication number	US-2024118318-A1
Application number	US-202318483127-A
Country	US
Kind code	A1
Filing date	Oct 9, 2023
Priority date	Oct 11, 2022
Publication date	Apr 11, 2024
Grant date	—

Abstract

A system and method for determining an open or closed position of a magnetically actuated vacuum interrupter. The method includes applying a voltage signal of a known voltage to the actuator over a predetermined period and determining a change in current over time during the period when the voltage signal is applied to the actuator using an output of a Rogowski coil. The method also includes calculating the inductance using the voltage and the change in current over time at a predetermined time during the period and using the calculated inductance to determine whether the actuator and thus the vacuum interrupter are in the open or closed position.

First claim

What is claimed is:

1 . A method for determining a position of a magnetic actuator, the method comprising:
applying a voltage signal of a known voltage to the actuator over a predetermined period; determining a change in current over time during the period when the voltage signal is applied to the actuator; calculating the inductance of the actuator using the voltage and the change in current over time at a predetermined time during the period; and using the calculated inductance to determine the position of the actuator.

2 . The method according to claim 1 wherein applying a voltage signal includes applying a voltage signal for the predetermined period that is too short to cause the actuator to actuate.

3 . The method according to claim 1 wherein applying a voltage signal includes applying a pulse width modulation (PWM) signal having a duty cycle of 25%, and wherein the period is 1.04 ms.

4 . The method according to claim 1 wherein determining a change in current over time includes measuring the current over time.

5 . The method according to claim 1 wherein determining a change in current over time includes using an output of a Rogowski coil.

6 . The method according to claim 1 wherein calculating the inductance using the voltage and the change in current over time includes calculating the inductance at about 75% of the period.

7 . The method according to claim 1 wherein the magnetic actuator is part of a switching device including a switch, the magnetic actuator opening and closing the switch.

8 . The method according to claim 7 wherein the switch is a vacuum interrupter.

9 . The method according to claim 7 wherein the switching device is associated with a transformer in an electrical circuit.

10 . The method according to claim 7 wherein the position of the actuator provides an indication of whether the switch is open or closed.

11 . A method for providing an indication of whether a vacuum interrupter is open or closed, the vacuum interrupter being controlled by a magnetic actuator, the method comprising:
applying a voltage signal of a known voltage to the actuator over a predetermined period; determining a change in current over time during the period when the voltage signal is applied to the actuator using an output of a Rogowski coil; calculating the inductance using the voltage and the change in current over time at a predetermined time during the period; and using the calculated inductance to determine whether the actuator and thus the vacuum interrupter are in the open or closed position.

12 . The method according to claim 11 wherein applying a voltage signal includes applying a voltage signal for the predetermined period that is too short to cause the actuator to actuate.

13 . The method according to claim 11 wherein applying a voltage signal includes applying a pulse width modulation (PWM) signal having a duty cycle of 25%, and wherein the period is 1.04 ms.

14 . The method according to claim 11 wherein calculating the inductance using the voltage and the change in current over time includes calculating the inductance at about 75% of the period.

15 . The method according to claim 11 wherein the vacuum interrupter is associated with a transformer in an electrical circuit.

16 . A system for providing an indication of whether a vacuum interrupter is open or closed, the vacuum interrupter being controlled by a magnetic actuator, the system comprising:
means for applying a voltage signal of a known voltage to the actuator over a predetermined period; a Rogowski coil determining a change in current over time during the period when the voltage signal is applied to the actuator; means for calculating the inductance using the voltage and the change in current over time at a predetermined time during the period; and means for using the calculated inductance to determine whether the actuator and thus the vacuum interrupter are in the open or closed position.

17 . The system according to claim 16 wherein the means for applying a voltage signal applies the voltage signal for the predetermined period that is too short to cause the actuator to actuate.

18 . The system according to claim 16 wherein the means for applying a voltage signal applies a pulse width modulation (PWM) signal having a duty cycle of 25%, and wherein the period is 1.04 ms.

19 . The system according to claim 16 wherein the means for calculating the inductance calculates the inductance at about 75% of the period.

20 . The system according to claim 16 wherein the vacuum interrupter is associated with a transformer in an electrical circuit.

Assignees

• S & C Electric Co

Inventors

• Porter David G
• Dyer Thomas J
• Milton Joseph W
• Berman Andrew B
• Mcneil Christine E

Classifications

• G01R15/181 Primary

  using coils without a magnetic core, e.g. Rogowski coils · CPC title

• G01R31/3278

  of relays, solenoids or reed switches (measuring contact resistance G01R27/205; high voltage magnetic switches G01R31/3271, G01R31/333; testing electric windings G01R31/72; monitoring of fail safe circuits H01H47/002) · CPC title

• H01H47/002

  Monitoring or fail-safe circuits · CPC title

• H01H11/0062

  Testing or measuring non-electrical properties of switches, e.g. contact velocity (monitoring contacts H01H1/0015; monitoring gas density H01H33/563; monitoring vacuum H01H33/668; calibrating H01H69/01; adjusting H01H71/74; testing of electrical properties G01R31/333) · CPC title

• G01R31/3275

  Fault detection or status indication · CPC title