National Instruments DAQ Series User Manual

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National Instruments DAQ Series User Manual Manual pdf 13 page image

Chapter 1 IntroductionDAQCard-700 User Manual 1-6 ni.com• Pollution degree 2 means that only nonconductive pollution occurs inmost cases. Occasionally, however, a temporary conductivity causedby condensation must be expected.• Pollution degree 3 means that conductive pollution occurs, or dry,nonconductive pollution occurs that becomes conductive due tocondensation.Clean the product with a soft nonmetallic brush. Make sure that the productis completely dry and free from contaminants before returning it to service.You must insulate signal connections for the maximum voltage for whichthe product is rated. Do not exceed the maximum ratings for the product.Remove power from signal lines before connecting them to ordisconnecting them from the product.Operate this product only at or below the installation category stated inAppendix A, Specifications.The following is a description of installation categories:• Installation category I is for measurements performed on circuits notdirectly connected to MAINS 1. This category is a signal level such asvoltages on a printed wire board (PWB) on the secondary of anisolation transformer.Examples of installation category I are measurements on circuits notderived from MAINS and specially protected (internal)MAINS-derived circuits.• Installation category II is for measurements performed on circuitsdirectly connected to the low-voltage installation. This category refersto local-level distribution such as that provided by a standard walloutlet.Examples of installation category II are measurements on householdappliances, portable tools, and similar equipment.• Installation category III is for measurements performed in the buildinginstallation. This category is a distribution level referring to hardwiredequipment that does not rely on standard building insulation.Examples of installation category III include measurements ondistribution circuits and circuit breakers. Other examples ofinstallation category III are wiring including cables, bus-bars,1 MAINS is defined as the electricity supply system to which the equipment concerned is designed to be connected either forpowering the equipment or for measurement purposes.