BS EN 60871-1-2014 pdf download.Shunt capacitors for a.c. power systems having a rated voltage above above 1 000 V Part 1: General.
The resistance of the internal discharge device, if any, shall be checked by a resistance
measurement (see Clause 21 and Annex D).
The choice of the method is left to the manufacturer.
The test shall be made after the voltage test of Clause 9.
12 Sealing test (routine test)
The unit (in non-painted state) shall be exposed to a test that will effectively detect any leak of the container and bushing(s). The test procedure is left to the manufacturer, who shall describe the test method concerned.
If no procedure is stated by the manufacturer, the following test procedure shall apply. Unenergized capacitor units shall be heated throughout for at least 2 h. so that all parts reach a temperature not lower than 20 °C above the maximum value in Table 1. No leakage shall occur. It is recommended that a suitable indicator is used.
13 Thermal stability test (type test)
13.1 General
This test is intended to
a) determine the thermal stability of the capacitor under overload conditions,
b) condition the capacitor to enable a reproducible loss measurement to be made.
13.2 Measuring procedure
The capacitor unit subjected to the test shall be placed between two other units of the same rating which shall be energized at the same voltage as the test capacitor Alternatively, two dummy capacitors each containing resistors may be used, The dissipation in the resistors shall be adjusted to a value such that the case temperature of the dummy capacitors near the top opposing faces are equal to or greater than those of the test capacitor. The separation between the units shall be equal to or less than the normal spacing. The assembly shall be placed in a heated enclosure with no forced ventilation and in the most unfavourable thermal position according to the manufacturer’s instructions for mounting on site. The ambient air temperature shall be maintained at or above the appropriate temperature shown in Table 2. It shall be checked by means of a thermometer having a thermal time constant of approximately 1 h. This thermometer shall be shielded so that it is exposed to the minimum possible thermal radiation from the three energized samples.
The test capacitor shall be subjected for a period of at least 48 h. to an a.c. voltage of substantially sinusoidal form. The magnitude of the voltage throughout the test shall be adjusted to give a calculated output, using the measured capacitance (see 7.1). of at least 1,44 times its rated output.
During the last 6 h the temperature of the container near the top shall be measured at least four times. Throughout this period of 6 h, the temperature rise shall not increase by more than I K. Should a greater change be observed, the test shall be continued until the above requirement is satisfied for four consecutive measurements during a subsequent 6 h period. In case the thermal stability condition is not reached In 72 h, the test shall be stopped and the capacitor shall be declared to have failed in this test.
Before and after the test the capacitance shall be measured (see 7.1) within the temperature range according to 5.2 and the two measurements shall be corrected to the same dielectric temperature. The difference between the two measurements shall be less than an amount corresponding to either breakdown of an element or operation of an internal fuse.
When interpreting the results of the measurements, two factors shall be taken into account:
— the repeatability of the measurements;
— the fact that internal change in dielectric may cause a small change of capacitance. without puncture of any element of the capacitor or operation of an internal fuse having occurred.
When checking if the temperature conditions are satisfied, fluctuations of voltage, frequency and ambient air temperature during the test should be taken into account. For this reason, it is advisable to plot these parameters, and the temperature rise of the container as a function of time.
Units intended for 60 Hz installation can be tested at 50 Hz and units intended for 50 Hz can be tested at 60 Hz provided that the specified output is applied. For units rated below 50 Hz the test conditions should be agreed between purchaser and manufacturer.
14 Measurement of the tangent of the loss angle (tan 6) of the capacitor
at elevated temperature (type test)
14.1 MeasurIng procedure
The capacitor losses (tan 6) shall be measured at the end of the thermal stability test (see Clause 13). The measuring voltage shall be that of the thermal stability test.
14.2 Requirements.BS EN 60871-1-2014 pdf download.