Conformity - November 2008 - (Page 47) Bonding for Grounding testing, or Ground Bond testing, verifies the integrity of the ground connection on the stove. All exposed or accessible dead metal parts shall be connected to protective ground. The test requires application of twice the rating of the branch circuit over-current protection device required to electrically protect the equipment for a period of two minutes. The conductor shall not open during the test. There is no requirement for this test in production, but there is a requirement for Ground Continuity testing. In addition, CSA 22.2 No. 0.4, Bonding of Electrical Equipment, should be reviewed for additional grounding requirements and tests. The Ground Continuity test requires that all appliances be tested for electrical connection between ground and the appliance. This test can be performed with an ohmmeter, battery/buzzer combination, or similar items. Most hipot testers incorporate a Ground Continuity test that meets these requirements. Part 2—Solar Power Solar power is once again back in the spotlight as a viable source of alternative energy. Solar power is based upon the photovoltaic cell. The term photovoltaic refers to any device which produces free electrons when exposed to light. The photovoltaic cell is the smallest discrete element in a photovoltaic module that performs the conversion of light into electrical energy to produce a DC current and voltage. Crystalline photovoltaic cells are manufactured using two different techniques, either crystal growing or casting. The growing technique creates a silicon wafer by pulling it from molten silicon. The casting process uses a reusable graphite mold to produce blocks of silicon. The silicon blocks are then cut into wafers. A photovoltaic cell typically produces 0.5V. To increase the voltage, 36 cells are typically assembled into a photovoltaic module to provide enough voltage to charge a 12V battery. A photovoltaic module also includes ancillary parts, such as interconnections, the terminals intended to generate DC power from sunlight. A photovoltaic module is often referred to as a solar panel. Electrical Safety Testing for Photovoltaic Cells and Panels There are several standards that cover various aspects of photovoltaic module testing, including the following: • UL 1703, Flat-Plate Photovoltaic Modules and Panels • IEC 61730, Photovoltaic (PV) module safety qualification • IEC 61215, Crystalline silicon terrestrial photovoltaic (PV) modules - Design qualification and type approval • IEC 61646, Thin-film terrestrial photovoltaic (PV) modules – Design. UL 1703 and IEC 61730 are the basic standards, covering requirements for safety and construction of photovoltaic modules to address prevention of electrical shock and fire hazards. These two base standards are to be used in conjunction with IEC 61215 and IEC 61646. IEC 61215 is specific to crystalline silicon modules, and IEC 61646 to thin-film modules. UL 1730 will soon be superseded by UL IEC 61730. IEC 61730-1 -2 1st Ed. – 2004, and UL 1703 3rd Ed. - 2002 Electrical safety tests called out in IEC 61730 and UL 1703 include Dielectric Withstand, Bonding Path Resistance, and Insulation Resistance. Manufacturing and production tests require Dielectric Withstand and Ground Continuity testing be performed on every module. Bonding Path Resistance testing outlined in the standard requires the resistance between the ground terminal or lead and any accessible conductive part be less than 0.1 ohms. The resistance is to be measured with a test current of 2 times the fuse rating. Ground Continuity production testing requires only that there is an electrical connection between the ground terminal and all accessible conductive parts. Note that, if CSA certification is required, CSA 22.2 No. 0.4 – 2004, Bonding of Electrical Equipment should be reviewed. When a production continuity november 2008 Conformity 7 http://www.haefelyemc.com http://www.haefelyemc.com
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