DSH 721 Abnormal operation
http://decisions.iecee.org/icons/ecblank.gif DSH 721
Abnormal operation
19.11.2
60335-1(ed.4);am1;am2
Question:
In clause 19.11.2 of IEC 60335-1 (Ed 4.2) failure conditions in items a) through g) apply to circuits continuously connected to the supply mains. The question is in relation to the conditions that are assessed after the 19.11.2 failure tests in standby mode operation:
Are tests of clause 19.11.3 and 19.11.4 applicable after the first failure resulting from clause 19.11.2 testing?
Decision:
The tests in 19.11.2 are done in a specific order and in such a way that at first a hardware failure according to 19.11.2 is applied in the Protective Electronic Circuit (PEC) and, then, second, the relevant tests of clause 19 protected by this PEC are applied conducted.
It must be understood that if a hardware failure according to clause 19.11.2 is applied in the PEC under consideration and it causes a shut down, then as per 5.3, it is meaningless to apply the relevant test of clause 19 protected by this PEC.
However, it must also be understood that the PEC providing protection during the relevant test of clause 19 will have to be tested according to 19.11.2 as an electronic circuit. If during this test a shut down occurs, 19.11.3 requires that the 19.11.2 test is repeated with a fault in the circuit that caused the shut down.
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