Apparatus and method for measuring the breakdown voltage between two electrodes separated by a dielectric

• US 5,633,591 A
• Filed: 08/05/1996
• Issued: 05/27/1997
• Est. Priority Date: 04/19/1994
• Status: Expired due to Fees

• Current Assignee: Gas Technology Institute
• Original Assignee: Gas Research Institute (GTI Energy)
• Inventors: Griffith, William A., Childress, William E.
• Primary Examiner(s): Snow, Walter E.
• Application Number:
  US08/692,505
• Time in Patent Office: 295 Days
• Field of Search: 324/379, 324/380, 324/399, 324/402, 73/116, 73/117.3
• US Class Current: 324/399
• CPC Class Codes: F02P 17/12 Testing characteristics of the spark, ignition voltage or current testing of sparking plugs H01T13/60
• CPC Class Codes: F02P 2017/006 using a capacitive sensor

Abstract

An apparatus and method for measuring a breakdown voltage between two electrodes separated by a dielectric. The output of a sensor perceiving the voltage across the two electrodes is transferred to a peak-hold circuit. A spark through the dielectric and across the two electrodes is detected, Restrikes between the electrodes are clamped by precluding further transfers of sensor output to the peak-hold circuit for a predetermined period of time subsequent to the detected occurrence of the spark.

Claims

1. An apparatus for measuring a breakdown voltage between two electrodes separated by a dielectric, the apparatus comprising:

sensor means for sensing a voltage across the two electrodes, the sensor means providing an output charge substantially indicative of the voltage across the two electrodes;

peak-hold means operably coupled to the sensor means for storing a charge substantially indicative of a total of the output charge provided by the sensor means prior to reaching the breakdown voltage between the two electrodes, the peak-hold means providing an output voltage substantially indicative of the stored charge as an output of the apparatus;

spark detection means operably coupled to the sensor means for detecting the occurrence of a spark through the dielectric and across the two electrodes; and

restrike clamping means for substantially precluding further transfer of charge from the sensor means to the peak-hold means for a pre-determined period of time subsequent to and in response to the detected occurrence of the spark.

2. The invention according to claim 1 wherein the sensor means includes a conductive tube-like member substantially surrounding at least a portion of an insulated conductor operably attached to one of the electrodes:

the conductor insulation serving as a dielectric between the tube-like member and the conductor,

the tube-like member, conductor insulation and insulated conductor collectively forming a capacitor.

3. The invention according to claim 1 wherein the peak-hold means includes at least one steering diode and at least one storage capacitor, the steering diode providing a current path between the storage capacitor and the sensor means.

4. The invention according to claim 3 wherein the peak-hold means further includes discharge means for rapidly discharging the storage capacitor.

5. The invention according to claim 4 wherein:

the storage capacitor includes a first terminal and a second terminal,

the discharge means includes a transistor operably coupling the first terminal and the second terminal to a ground potential whenever the transistor is turned on.

6. The invention according to claim 1 wherein the spark detection means includes a steering diode operatively coupled to the sensor means and a zener clamp diode operably coupled to the steering diode.

7. The invention according to claim 1 wherein:

the restrike clamping means includes at least one steering diode operably coupled to the sensor means,

the steering diode being activated by the spark detection means,

the steering diode substantially precluding further transfer of current from the sensor means to the peak-hold means.

8. The invention according to claim 1 wherein the apparatus further includes an analog-to-digital converter operably coupled to the peak-hold means,

the analog-to-digital converter converting the output voltage of the peak-hold means to a digital value substantially indicative of the output voltage.

9. A process for measuring a breakdown voltage between two electrodes separated by a dielectric, the process comprising the steps of:

sensing a voltage across the two electrodes;

outputting a charge substantially indicative of the voltage across the two electrodes;

transferring the charge to a storage capacitor until reaching the breakdown voltage between the two electrodes;

storing within the storage capacitor [a]the charge substantially indicative of a peak voltage across the two electrodes;

detecting the occurrence of a spark through the dielectric and across the two electrodes; and

precluding further transfers of charge to the storage capacitor for a pre-determined period of time subsequent to and in response to detecting the occurrence of a spark.

10. The invention according to claim 9 wherein the process further includes the step of converting the charge stored within the capacitor to a digital value substantially indicative of the stored charge.