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Related to hiccup mode, how are power sources classified per 5.2.2 for a 3.6 V output?

More specifically you asked, in a hiccup mode (repetitive peaks), with a pulse off time less than 3 seconds as shown in IEC 62368-1, 5.2.2.5 that does not result in a fault condition of a main or supplementary safeguard, but it is part of the normal operating conditions of the equipment. How can I classify the power sources according to 5.2.2 knowing that under single fault conditions I have the hiccup mode for current with a 3.6V output, Do I have to consider I (peak) for classification?

 

In response, you seem to be indicating you have a power source output that under single fault conditions produces a 3.6 Vpeak in hiccup mode (i.e., with repetitive pulses less than 3 seconds).  You seem to be asking about the current (I) limits for the 3.6 Vpeak output when classified per 5.2.2.

 

First, please note there have been some considerable changes with regards to repetitive pulses in IEC 62368-1:2018 (Ed. No. 3) versus what was in IEC 62368-1:2014 (Ed. No. 2).  Please see our previous Q&A posts that discussed some of these changes, including the definition of a ‘pulse.’

 

https://62368-ul-solutions.com/engineers/whats-the-definition-for-pulse-in-iec62368-1/    

 

https://62368-ul-solutions.com/engineers/update-62368-clause-5.2.2.5-states-that-voltage-cannot-go-over-42.4vpk-if-less-than-3secs.-so,-does-this-mean-in-hiccup-mode-the-output-cannot-go-over-42.4vpk-therefore-a-48v-output-will-not-pass-to-es1-this-is-different-to-60950/

 

However, for your situation, these changes don’t appear to impact you because it appears that you may be missing a fundamental principle of Clause 5’s Electrical Energy Source (ES) classifications.  

 

Per 5.2.2.1 (Electrical energy source ES1 and ES1 limits – General), “ For any voltage up to the voltage limit, there is no limit for the current. Likewise for any current up to the current limit, there is no limit for the voltage, see Figure 21.”  Similarly, per 5.2.2.5 (Limits for repetitive pulses), “… a repetitive pulse electrical energy source class is determined from either the available voltage or the available current. If the voltage exceeds the limit, then the current shall not exceed the limit. If the current exceeds the limit, the voltage shall not exceed the limit.”

 

Since your pulse time is less than 3 seconds, per 5.2.2.5 the peak limits of 5.2.2.2 apply.   However, since per 5.2.2.1, your 3.6 Vpeak output is less than the ES1 voltage limit of 42.4 Vpeak, the current (I) limit is not a consideration in ES1 classification because you do not exceed the voltage limit.  Therefore, based on the information you provided, it appears the output of your power source indeed complies with ES1 even under single fault conditions and even during hiccup mode.

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