opyi TR62470@IEC:2011(E) - 11 - angle α with the base plate at which the cable specimen starts sliding(static COF)or continues sliding (kinetic COF); calculated oF (one or both types); relative humidity and ambient temperature during the test. 3.3 Method C: sloped cable test 3.3.1 General This subclause describes a technique for the measurement of the CoF between a cable Reuters (pushing,pulling,blowing,etc.)of the cable in the duct; see IEC 60794-1-1:2001,Annex C(to be IEC/TR 62691). Sci cientific), 3.3.2 Sample The test sample comprises a duct specimen and a cable specimen of the type under the effects of wearand contamination. ThecablespecimenisofalengthconsistentwiththeapparatusofFigure3.Thecable specimen often must be straightened such that it will be straight when mounted in the ec apparatus. Note that most apparatus for this test hold the cable under tension, which will assist in straighteningthe cable specimen. The duct specimen is shorter than the cable specimen. Straightening of the duct specimen andashortlengthofthespecimenisrequiredtoachieveaspecimenthatissubstantially dov straight.Takecarethatthelengthof the ductspecimenis short enoughbut notso short as to fail to lay flat on the cable specimen during the test. The (intrinsic) bend radius of the duct shall not result in opposite walls touching the cable, which would result in extra friction due to the spring action of the duct ends. A mass, typically cylindrical and surrounding the duct, may 9 beattached to theduct specimento simulate theeffects of upstreamfrictionof a lengthof duct and cable. Longer duct lengths are possible when using a straight (metal) cylinder around the duct specimen, which at the same time serves as a weight. The total weight of duct specimen and cylinder per unit of length shall be between 1 and 10 times the weight of the cable specimen per unit of length. The ends of the duct specimen may be treated with a conical drill or a similar tool, such that the cable is only in contact with the inner surface of the duct. The combination of the straightness of the duct and its length can affect the results. No further 3.3.3 Apparatus mounted straight. Before finishing clamping the cable specimen a short specimen of duct is repr sleeved around it, see 3.3.2. The tension of the cable specimen in the fixture must be large enoughtostraightenthecablespecimensufficientlysuchthatthedeviationofthecablefrom tion a straight line is minimised (see the discussion in 3.3.2). The deviation is typically less than O.5° which can be estimated by visual examination; if in doubt it should be measured. The clamping device with specimens can be tilted with respect to the horizontal. Incontrolledwhen orin Copyrighted material li - 12 - TR62470@IEC:2011(E) I licensed to BR Demo by Thomson Reuters ( Duct Cable Mass IEC 2412/11 (Scientific), Figure3-Sketchof thesloped cabletest. Inc., 3.3.4 Procedure , subscriptions.techstreet.com, The procedure follows the intent of the following steps: Place the cable specimen in one side of the clamping device.Sleeve the duct specimen the clamping device, tensioning it such that the cable specimen is straight. Move the duct specimen to the end of the apparatus to be raised. See the discussion in 3.3.3. Static COF-Tilt the clamping device with duct and cable specimens.Measure the angle α at which the duct specimen starts sliding. downloaded on N Kinetic (sliding) COF - Tilt the clamping device to the angle α to be evaluated. Start the duct specimen moving by hand, e.g. by tapping the specimen. If the duct does not continue sliding to the end of the cable, increase the angle α by a small increment and repeat the test until the duct slides. If the duct does initially continue sliding, decrease the angle α by a small increment and repeat the test until the duct does not slide to the end of calculate kinetic COF. For a valid measurement to be recorded the specimen must have travelled from the top to the bottom of the apparatus in one contin