TEST + QUALITY ASSURANCE Source: CAMI Research Hipot test results after programming tester to keep shield at ground potential. To reach the test voltage without first hitting the trip current, care must be taken to adjust the voltage ramp in accordance with the length of the cable. shield and measuring its leakage to the totality of all other conductors. So simply programming the system to keep the shield at ground potential for the duration of the test alleviates this problem. Finding leakage between each conductor and the shield is the goal, and this is accomplished without ever needing to apply voltage to the shield itself, as long as the conductor of interest is measured at high voltage against a grounded shield. Potential danger in testing long cables at high voltage For safety reasons, most hipot test equipment limits the maximum current flow produced by the equipment when a low resistance path develops during a test. Thus, should an operator inadvertently make contact with open pins during a high voltage test, the current flow is not sufficient to endanger the operator‘s life. However, when testing long cables, the energy stored in the cable must also be considered: 1/2 CV 2 . As the test voltage increases, the energy stored also increases with the square of the voltage. So, a cable tested at 1,000 Vdc compared to 10 Vdc stores 10,000 times the energy. Depending on the conditions, inadvertent contact with an open pin at the far end of a long cable may pose a lethal danger, particularly if a nearby individual remains unaware that a high voltage test is in progress. Caution should be taken to cap open cable ends and inform anyone nearby about the plans for testing. Source: CAMI Research Zusammenfassung Um genaue, zeitnahe und sichere elektrische Messungen des Kabel- und Isolationswiderstands in langen Kabeln zu gewährleisten, müssen die Hochspannungs-Kabeltester unter anderem und wie im Artikel zu lesen, Kontrollen zur Einstellung der Rampenrate und Verweilzeit vorweisen. Résumé Afin de garantir des mesures électriques précises, rapides et garantie de câble et la résistance d‘isolation dans les longs câbles, les testeurs de câbles haute tension doivent, entre autres et comme décrit dans l‘article, disposer de commandes pour régler le taux de rampe et le temps de séjour. Zusammenfassung russisch Для обеспечения точных, своевременных и надежных электрических измерений сопротивления кабелей и изоляции в случае длинных кабелей тестеры кабелей высокого напряжения, помимо прочего, должны обладать функциями контроля для настройки скорости рампы и времени ожидания. Conclusion The presence of parasitic capacitance in cables longer than 10 ft. (3 m) necessitate an increase in measurement time, to obtain an accurate reading of a cable‘s wire and insulation resistances. Inrush current experienced at the start of high voltage insulation tests require a controlled ramp to prevent exceeding a maximum safe current limit of 1.5 mA. A slow ramp-up in voltage to accommodate this requirement may significantly increase the test time. Because of the increased capacitance of a shield conductor and the resultant difficulty in reaching test voltage on the shield due to high initial charging current, insulation testing involving the shield may be limited to wire-to-shield only, and application of voltage shield-to-wire eliminated without loss of confidence in the shield insulation. Great care must be exercised by the technician during high voltage tests on long cables to avoid electric shock, as a potential lethal discharge current may far exceed the current produced by the tester itself. To ensure accurate, timely, and safe electrical measurements of wire and insulation resistance in long cables, hipot testers need to offer controls to set ramp rate, dwell time, and selectively exclude particular conductors, such as the shield, from application of high voltage. electronica, Booth A3-655; A3-107 www.camiresearch.com 66 EPP EUROPE November 2018
Accurate and reliable data with inspection hardware and self-programming software Driving M2M communication Long-term accuracy and stability of assembly equipment and the data transmitted to other assembly equipment are keys to M2M communication. This is especially true of automated optical inspection (AOI) and automated solder paste inspection (SPI) equipment. Without that accuracy and true M2M communication, the Smart Factory cannot exist. Norihiro Koike, Saki Corporation SPI and AOI are an integral part of M2M communication. Source: Saki Corporation Electronic assembly companies are lining up to be part of initiatives, such as Industry 4.0 and the Smart Factory. Many of these have been driven by the major pick-and-place manufacturers who are working to integrate their assembly lines with equipment and processes that can operate without an operator. These lines need to function in all types of production environments without even a micron of deviation. Fiducials relayed from one machine to another must be precise and accurate and centers aligned. Data collection must also contain the necessary parameters and be accurate and easily transferable, with each system operating in sync with the other systems in the line. This operation must be maintained for years, without having to stop for repair, to alter the process, or to tweak, realign, or recalibrate the equipment. A lot more is now demanded from inspection equipment. There are more customized boards and variations in the printed circuit boards being produced. Boards might look the same, but can actually be different, so they need to be programmed differently. With shorter product life cycles, configurations change frequently. Inspection machines are being created that are easier to program, handle, are more accurate, and that adapt to more board types. All the parameters and variations that can be encountered have to be accommodated, even if they’re only needed for small production runs. The complexity of production has increased so greatly that the equipment and lines must not only be easy to control, but also controlled by one system. No longer can one person stand in front of each machine. One person needs to be able to control the entire line and do it remotely. Accuracy starts with the hardware. The hardware platform and its basic stability, structure, materials, configuration, and construction will make a difference in how the accuracy holds up over time and how reliable the data collected will be. The assembly process involves high-speed continuous movement of parts, often operating EPP EUROPE November 2018 67
