小米 发表于 2012-11-5 11:03

DSH 420 Enclosure leakage current caused by external voltage


http://decisions.iecee.org/icons/ecblank.gif DSH 420

Enclosure leakage current caused by external voltage
19, 19.2 c)
60601-1(ed.2);am1;am2


Standard(s)- (year and edition):
IEC 60601-1:1988 Ed.2 Am1+Am2
Sub clause(s): 19, 19.2 c)
Sheet n°: DSH-420
Subject: Enclosure leakage current caused by external voltage
Key words: Enclosure, leakage current, external voltage
Confirmed by CTL at its 39th meeting, in Cologne
Question:
Since INTERNALLY POWERED EQUIPMENT has no reference to earth, the ENCLOSURE
LEAKAGE CURRENT flowing between different parts of the ENCLOSURE will not be affected
by an external voltage applied between earth and a SIGNAL INPUT or SIGNAL OUTPUT
PART. Therefore the ENCLOSURE LEAKAGE CURRENT for INTERNALLY POWERED
EQUIPMENT caused by such a voltage, should be measured as for CLASS II EQUIPMENT
with MD1 between the ENCLOSURE and earth according to Figure 18. Further, the external
voltage to be applied should be specified in Sub-clause 19.4 g) 3), in a similar way as in Subclause
19.4 h) 8) and Figure 25 (Measurement of the PATIENT LEAKAGE CURRENT flowing
from the APPLIED PART to earth, caused by an external voltage between earth and any
SIGNAL INPUT or SIGNAL OUTPUT PART), except that supply frequency does not apply for
EQUIPMENT with an internal battery.
Decision:
To clarify this issue, Sub-clause 19.4 g) 3) should read : .......”and INTERNALLY POWERED
EQUIPMENT are tested for ENCLOSURE LEAKAGE CURRENT flowing between the
ENCLOSURE and earth and also between different parts of the ENCLOSURE (measuring
device applied as MD1 and MD2 in Figure 18).”

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