IEC 62230-2013 pdf download.Electric cables – Spark-test method.
The spark-test method specified in this standard is intended for the detection of defects in the insulation or sheathing layers of electric cables. For single-core cables with no outer metallic layer, the general process is accepted as being equivalent to subjecting samples of those cables to a voltage test in water.
This standard specifies the operational requirements for the spark-test equipment, as well as the principal characteristics, functional parameters and calibration procedures for each type of test equipment.
2 Types of voltage waveform
For the purposes of this standard, the types of voltage waveform used for spark-testing are divided into the following groups:
a.c. an alternating current (a.c.) voltage of approximately sine-wave form, at the
industrial frequency of 40 Hz to 62 Hz;
d.c. a direct current (d.c.) voltage;
an alternating current (a.c.) voltage of approximately sine-wave form, at frequencies between 500 Hz and 1 MHz;
pulsed a voltage waveform comprising a fast rise time and highly damped wave-tail, as defined in 4.2.
NOTE Provided the manufacturer can demonstrate equivalent effectiveness, hi. voltages at frequencies below 500 Hz may be used.
3 Procedure
The insulated conductor or sheathed cable shall be passed through an electrode energized at the test voltage. The method detailed in this standard provides for the application of a.c., d.c., h.f. and pulsed voltages.
The requirements for voltage waveform, frequency and test voltage are given in 4.2 and Clause 5. The maximum speed at which the cable shall pass through the electrode is determined by the minimum residence time specified in 4.6.
4 Equipment
4.1 Safety
To limit the effect of electric shock to personnel, for all types of voltage source, the equipment shall be constructed in such a way that the short-circuit current is limited to less than 10 mA r.m.s. or equivalent.
This requirement is additional to, or may be superseded by, any national regulation that
prevails at the time.
NOTE Guidance on the limiting of shock currents can be found in IEC 60479-1 and lEG 60479-2.
Further aspects of operational safety are given in Annex C.
4.2 High voltage source
The high-voltage electrode shall be supplied in one of the following forms, as defined in Clause 2: a.c., d.c., hi. or pulsed.
For a d.c. test, connection to the test electrode shall be by means of a low capacitance unscreened lead. For d.c. and pulsed voltage testing, the test electrode may be either positive or negative polarity, the other pole being earthed.
The requirements for pulsed waveforms are presented In Figures 1,2 and 3.
For pulsed waveforms, the rise time of the wave front shall reach 90 % of the specified peak value in less than 75 pas — see Figure 1. Fluctuations of the actual peak value, due to variations of input power into the generator, shall not exceed ±2 % of the specified peak value
— see Figure 2. The peak value shall not show more than 5 % reduction in the event of an increase of capacitive load of 50 pF, during the operation, from an initial load of 25 pF between electrode and instrument ground. The time that each pulse remains at a voltage greater than 80 % of the specified peak voltage shall be between 20 ps and 100 jis — see Figure 3. The pulse repetition frequency shall be greater than 170 per second and less than 500 per second. This corresponds to pulse separations between 2 000 ps and 5 880 iS. Visible or audible corona shall be evident in the electrode structure when operating at the specified voltage.IEC 62230 pdf free download.