IEC 60885-3-2015 pdf free download.Electrical test methods for electric cables – Part 3: Test methods for partial discharge measurements on lengths of extruded power cables. 5 Partial discharge tests 5.1 Test apparatus 5.1.1 Equipment The equipment consists of a high-voltage alternating voltage supply having a rating adequate to energise the length of cable under test, a voltmeter for high voltages, a measuring circuit, a discharge calibrator, a double pulse generator and, where applicable, a terminal impedance or reflection suppressor. All components of the test equipment shall have a sufficiently low noise level to achieve the required sensitivity. The frequency of the test supply shall be in the range 45 Hz to 65 Hz with a waveshape approximating to a sinusoid with the ratio of peak to r.m.s. values being equal to 2 with a maximum tolerance of 5 %. 5.1.2 Test circuit and instruments The test circuit includes the high voltage power supply, test object, the coupling capacitor and the HV and PD measuring equipment. The measuring circuit consists of the measuring impedance (input impedance of the measuring instrument and the input unit which is selected to match the cable impedance), the connecting lead and the measuring instrument. The measuring instrument or detector includes a suitable amplifying device, an oscilloscope, or other instrument to indicate the existence of partial discharges and to measure the apparent charge. The measuring system shall comply with IEC 60270. 5.1.3 Double pulse generator A double pulse generator is an instrument producing two equal pulses (with the same apparent charge) following each other within a time interval which can be varied between 0,2 as to 100 pis. The rise time of the pulses shall not exceed 20 ns (10 % to 90 % of peak value); the time between 10 % values of the front and the tail shall not exceed 150 ns. The pulses may be synchronized with the power frequency. 5.1.4 Terminal impedance A terminal impedance is an impedance, equal in value to the characteristic impedance of the test object, which is connected to the open end of the cable remote from the detector. It may be a combination of resistance and capacitance (R & C) or resistance, capacitance and inductance (R, C & L). The components shall be suitable for operation at the test voltage to be applied to the cable under test. Additional requirements are specified in section 5.6. 5.1.5 Reflection suppressor...
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