Electrical pathway intermittent fault detection
Testing to detect intermittent electrical pathways is described. Applied currents may be reversed to fully test all components of a workpiece. Various testing methodologies may be employed. These methodologies may include Time Domain Reflectometry (TDR), mechanical agitation, dark current/voltage testing, (dark IV), i.e., electrical testing of a workpiece using applied electricity, and thermographic imaging, e.g., infra-red thermal imaging. The sensed voltage during agitation may be compared to a benchmark voltage to determine whether or not an intermittent failure exists.
1. An electrical pathway intermittent fault detection system comprising:
an electrical pathway tester comprising a mechanical vibration generator;
an exposed electrical sensor;
an electrical power supply; and
a microcontroller,
wherein the microcontroller is configured, using outputs from the electrical pathway tester, to determine whether an intermittent electrical pathway is present in a junction-box of the photovoltaic laminate and to provide a signal when an intermittent electrical pathway is detected, and
wherein the microcontroller is further configured to consider a frequency of vibration of the mechanical vibration generator applied to the photovoltaic laminate by the mechanical vibration generator, and further configured to consider voltages sampled from the photovoltaic laminate, the sampling conducted when the mechanical vibration generator is in contact with the photovoltaic laminate, the sampling rate of considered voltages being faster than the frequency of vibration of the mechanical vibration generator.
2. The system of claim 1 wherein the mechanical vibration generator is configured to generate vibrations across a range of frequencies,
wherein the power supply is configured to provide electrical power to the vibration generator,
and
wherein the microcontroller is further configured to compare the voltages sampled with one or more target voltage, to determine whether an intermittent electrical pathway is present in the photovoltaic laminate and to provide a signal when an intermittent electrical pathway is detected.
3. The system of claim 2 further comprising a shared bus, the shared bus coupled to two or more of: the mechanical vibration generator, the voltage sensor, the power supply, and the microcontroller.
4. The system of claim 2 wherein the frequency of vibration of the mechanical vibration generator is one-tenth or less than the frequency of the sampling rate of considered voltages.
5. The system of claim 2 wherein the one or more target voltage is predetermined, calibrated for the photovoltaic laminate, and is in a range of 0.002 volts to 20 volts.
6. The system of claim 2 wherein voltages sampled from the photovoltaic laminate result first from a forward bias current and then from a reverse bias current, the current provided by the power supply, the forward bias current used to detect soldering failure in the photovoltaic laminate, the reverse bias current used to detect diode failure in the photovoltaic laminate.
7. The system of claim 2 wherein the signal when an intermittent electrical pathway is detected is in an audible frequency range of 20 Hz to 20,000 Hz.
8. The system of claim 2 wherein the mechanical vibration generator is mounted on an automated arm.
9. An electrical pathway intermittent fault detection device comprising:
a thermal imaging sensor;
an electrical sensor;
an electrical power supply; and
a microcontroller,
wherein the microcontroller is configured to apply a forward bias current through an electrical connection of a workpiece for a first period of time and to apply a reverse bias current through the electrical connection of the workpiece for a second period of time,
wherein the microcontroller is further configured to report information observed by the thermal imaging sensor during the first period of time and during the second period of time, and
wherein the microcontroller is further configured to consider a frequency of vibration of a mechanical vibration generator applied to the workpiece by the mechanical vibration generator, and further configured to consider voltages sampled from the workpiece, the sampling conducted when the mechanical vibration generator is in contact with the workpiece, the sampling rate of considered voltages being faster than the frequency of vibration of the mechanical vibration generator.
10. The device of claim 9 wherein the workpiece is a photovoltaic laminate and the electrical connection resides in a potted junction box.
11. The device of claim 9 wherein the thermal imaging sensor is an infra-red sensor.
12. The device of claim 9 wherein the electrical connection has a maximum current and the forward bias current and the reverse bias current do not exceed the maximum current.
13. The device of claim 9 wherein the first period of time and the second period of time do not overlap and are each no longer than ten seconds.
14. The device of claim 9 wherein the first period of time occurs after the second period of time.
15. The device of claim 9 wherein the first period of time occurs before the second period of time.
16. A process of electrical pathway intermittent fault detection comprising:
providing an exposed direct-contact vibration generator;
providing a plurality of electrical sensors;
providing an electrical power supply; and
providing a microcontroller,
wherein the microcontroller is configured to determine whether an intermittent electrical pathway is present in a junction-box of a photovoltaic laminate and to provide at least an audible or visual signal when an intermittent electrical pathway is detected, and
wherein the microcontroller is further configured to consider a frequency of vibration of the direct-contact vibration generator applied to the photovoltaic laminate by the direct-contact vibration generator, and further configured to consider voltages sampled from the photovoltaic laminate, the sampling conducted when the direct-contact vibration generator is in contact with the photovoltaic laminate, the sampling rate of considered voltages being faster than the frequency of vibration of the direct-contact vibration generator.
17. The process of claim 16 wherein the direct-contact vibration generator is mounted on an automated arm.
18. The process of claim 17 where the automated arm is configured to receive instructions from the microprocessor.
19. The process of claim 16 further comprising applying a forward current bias to the photovoltaic laminate and applying a reverse current bias to the photovoltaic laminate.
20. The process of claim 19 wherein the forward current bias and the reverse current bias are applied for the same amount of time but not applied during the same time period.