AS IEC 60990:2018 pdf download
AS IEC 60990:2018 pdf download.Methods of measurement of touch current and protective conductor current.
4 Test site
4.1 Test site environment
Test site environmental requirements shall be as specified in the EQUIPMENT standard. If limit values of less than 70 μA r.m.s. or 100 μA peak are specified, or if the EQUIPMENT contains large shields which may be driven by high-frequency signals, product committees shall refer to Annex B.
4.2 Test transformer
The use of a test transformer for isolation is optional. For maximum safety, a test transformer for isolation (T2 in Figure 2, T in Figure 6 to Figure 14) shall be used and the main protective earthing terminal of the EQUIPMENT under test (EUT) earthed. Any capacitive leakage in the transformer shall then be taken into account. As an alternative to earthing the EUT. the test transformer secondary and the EUT shall be left floating (not earthed), in which case the capacitive leakage in the test transformer need not be taken into account.
If transformer T is not used, the EUT shall be mounted on an insulating stand and appropriate safety precautions taken, in view of the possibility of the body of the EUT being at hazardous voltage.
4.3 Earthed neutral conductor
EQUIPMENT intended for connection to a TT or TN power distribution system shall be tested with minimum voltage between neutral and earth.
NOTE Descriptions of various power distribution systems are given in Annex
The protective conductor and the earthed neutral conductor for the EUT should have a voltage difference of less than I % of line-to-line voltage (see example in Figure 1).
A local transformer, see 4.2, will achieve this requirement.
Alternatively, if the voltage difference is 1 % or more, the following are examples of methods which, in some cases, will avoid measurement errors due to this voltage:
— connecting the terminal B electrode of the measuring instrument network to the neutral terminal of the EUT instead of the protective earthing conductor (see 6.1.2) of the supply;
— connecting the earthing terminal of the EUT to the neutral conductor, instead of the protective earthing conductor, of the supply.AS IEC 60990 pdf download.
