| ??? 07/14/05 11:39 Read: times |
#97345 - No pulse-wise calculation Responding to: ???'s previous message |
Prahlad said:
1. Once a signal cycle is passed can I immediately read the RMS value from these IC's or there is some delay. I remember in an earlier chip from Analog there was a settling time of 50ms+? You can, but the result will be wrong! These RMS/DC converters work by using a sophisticated averaging scheme. So, they need several periods to give correct results. If signal shows high crest factors, as it does when using phase angle controlling, then time constant of this averaging scheme must be at least ten times the period of signal. This means that an averaging time constant of 200msec for your 50Hz pulses is needed! So, a pulse-wise RMS/DC conversion is not possible with these chips. I have seen some of my competetors products using AD637 RMS to DC covnvertor chips. Maybe for the determination of certain parameters (overrange of absolute maximum power, for instance) it's useful to calculate the average of welding currents, where it's needed to sum over several pulses? Makes this sense to you? Kai |
| Topic | Author | Date |
| RMS to DC convertors. | 01/01/70 00:00 | |
| I am sorry | 01/01/70 00:00 | |
| what is provocative | 01/01/70 00:00 | |
| The reason why | 01/01/70 00:00 | |
| Didn't search first? | 01/01/70 00:00 | |
| Its too hot | 01/01/70 00:00 | |
| Disgusting... | 01/01/70 00:00 | |
| AD637 | 01/01/70 00:00 | |
| Re:AD637. | 01/01/70 00:00 | |
| are you sure they do? | 01/01/70 00:00 | |
| Wave shape? | 01/01/70 00:00 | |
| I agree.. | 01/01/70 00:00 | |
| Re: I agree. | 01/01/70 00:00 | |
| Re: Wave shape? | 01/01/70 00:00 | |
| Peak Vs RMS of social sensitivity | 01/01/70 00:00 | |
| Re: Peak Vs. RMS of social sensitivity. | 01/01/70 00:00 | |
| This is what I gathered! | 01/01/70 00:00 | |
| cost vs. accuracy | 01/01/70 00:00 | |
| No pulse-wise calculation | 01/01/70 00:00 | |
| True RMS | 01/01/70 00:00 | |
| cost | 01/01/70 00:00 | |
| Not all are that expensive | 01/01/70 00:00 | |
| re:cost | 01/01/70 00:00 | |
| At any rate | 01/01/70 00:00 | |
The AD637 is expensive here as well... | 01/01/70 00:00 |