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ADE7878 Overcurrent interrupt question

Question asked by almost_linear on Oct 10, 2014
Latest reply on Oct 21, 2014 by dlath

Hi there,

 

I am seeing some strange behaviour with the overcurrent interrupts and would also like some more info on the ADE7878 interrupt priority and the peak detect function of the chip.

 

I can NOT seem to set an interrupt based on an overcurrent event, unless I setup an interrupt on the overvoltage as well. Additionally the overvoltage threshold has to be set to a very low value (ie triggerable value) AND only after I have (Set initially and then) cleared the overvoltage interrupt bit, will I see the ADE7878 interrupting on overcurrent events (using an oscilloscope I confirm this).

 

Experimental setup - Hardware:

I am using an ADE7878 eval board (E78XX EVAL BZ D, 08-01912 REV E) along with its supplied evaluation software (on an XP laptop). I am injecting a 3-phase current using an accurate 3-phase generator (omicron – CMC256), through 3 current transformers. The voltage inputs are left floating. I have oscilloscope probes on all three current phases + IRQ1. The eval board is powered from an isolated/non-isolated supply as directed in the user guide.

 

Experimental setup - Software:

In PSM0 mode, running the Power Quality software ‘module’, I am setting MASK1.17 (OI) writing an appropriate value to the overcurrent threshold register OILVL+ setting MASK1.18(OV)+ writing an appropriate value to OVLVL. Control of the overcurrent events is accomplished using software control (omicron state sequencer) of the three phase generator (ie A ‘cyclical’ 3 phase signal is applied and every so often an overcurrent event is applied on one of the phases).

 

Could you please clarify/provide some info on this behaviour? Is it some interrupt priority issue or something totally different?

 

My next question is on the peak detect function of the ADE7878. I would like to acquire all three peaks of a three phase signal (50Hz) continuously (ie 3 peaks every 10 ms). Is this possible? If so what value do I need to right to the PEAKCYC register as it is a bit unclear in the manual?

 

Thanks and regards

Alex

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