Transcript

Test Setup for Flicker Measurement

Today, we’re measuring the flicker measurement capability of the BOLT. The flicker standard that we’re using is IEEE1453. With our test setup, we have a BOLT that is connected to an AC power supply, and we can program this power supply with arbitrary levels of voltage variation that should generate known flicker metrics.

To verify our setup, we have the two incandescent bulbs powered from the AC source and an optical sensor feeding into the oscilloscope as a separate measurement of the amount of optical light change output from the filaments when we subject it to different RMS voltage variations.

You can see the flicker now. We are actually around a flicker level of two, which is twice the threshold of irritability per IEEE1453. We are going to go through the conformance test that is specified in 1453, and also do some extra testing on the BOLT to make sure that the implementation is good.

Spot Check with PQ Canvas

So here’s a spot check. This should be around 2.2 and it is reading 2.2. We’re using PQ Canvas to get live readings from the BOLT. The flicker readings are slow because the standard calls for a 10-minute reading. So it takes a minimum of 10 minutes to get a new value once the level has changed per the standard.

IEEE1453 Conformance Test

Now, we’re going to go through the conformance test that is in the standard. IEEE1453 gives a list of 29 voltage change patterns and each of these should read a PST of one, plus or minus 0.05. These range in value from less than one change per minute, as long as one every 10 minutes, all the way to several thousand changes per minute, so we’re in the 10 to 20 hertz range here. It takes quite a bit of time to go through every level in the table because each one takes a minimum of 20 minutes to generate a valid reading.

So we’ve done that. We’ve subjected the BOLT to all 29 of these readings and we’ve let this accumulate in PQ Canvas. We have a PQ Canvas recording, and here, we’re looking at min/max and average voltage for all three channels throughout the conformance test. You can see that it’s over a 24-hour period to generate this data.

Conformance Test Results

Now each of these patterns should generate a PST of one, plus or minus 0.05 per the standard. So let’s see how the BOLT has computed the flicker. This is the flicker overview graph, which is a summary of the voltage changes. Here on the top, we have all three channels tied together and we’re looking at min/max and average, and the middle trace is PST, the bottom trace is PLT, the long-term flicker.

If we zoom in on the test portion, we can see that as the voltage is varying from very large but very slow changes to smaller and smaller changes and then widening up a little bit, PST is well within one plus or minus 0.05, and so is PLT. So the BOLT has passed the flicker conformance test per IEEE1453, but we wanna go a bit beyond that.

Dynamic Range and Linearity Testing

We wanna go beyond the minimum. We’re gonna check the dynamic range of the BOLT flicker measurement and also check its linearity to make sure that it is valid, not just at PST of one, but also at very low flicker levels and very high flicker levels.

Low End: PST of 0.2

We’re gonna set the power source to a very small change. This should be a PST of 0.2, which is the lower value that a flicker meter is meant to measure. You can see that the flicker is almost invisible. Even on the optical sensor it’s difficult to see because this is a very small amount of flicker, the smallest that’s measurable per the standard.

We will wait the appropriate amount of time for the calculations to happen. Again, the value is only updated per standard every 10 minutes, so we will come back here in a few minutes and check the BOLT’s measurement and make sure it’s measuring 0.2.

So we waited for the flicker calculations to complete and we are reading a PST of 0.20. So we’ve shown the low end of the BOLT flicker measurement ability is good.

High End: PST of 20

Now we’re gonna check the other end of the scale to make sure we have a wide dynamic range. We’re going to go to a PST of 20, which is an extreme level of flicker, to make sure the BOLT has enough dynamic range to cover the very low levels that you might see and very, very high levels.

Now we have a very visible amount of flicker. You can very easily see it in lights, you can very easily see it on the scope. We will let the BOLT process this data and make sure that it’s gonna be measuring well on the high end.

We are checking the BOLT’s very high flicker level measurement. We have a 20% volt of change. We can see a very large change in light output from the sensor because this is a huge amount of flicker. We check here in PQ Canvas, we’re measuring 21, which is the right amount for this level of flicker. That’s the top end of the recommendation for the dynamic range of a flicker meter.

Intermediate Level: PST of 4

Now we’re testing an intermediate level of flicker. This is a PST of four, well beyond the threshold of irritability and you can see the light’s flickering. The optical sensor is showing clear changes in light output. Let’s make sure the BOLT is measuring this correctly, and we can see that the BOLT is reading 3.97, 3.98 on all three channels. The BOLT has successfully measured flicker at this high but intermediate level.

Conclusion

We’ve fully tested the BOLT’s flicker measurement ability and it’s passed with flying colors. It met all the conformance test requirements that are in IEEE1453, and we’ve gone beyond that to test its linearity and ability to measure very low amounts of flicker and very high amounts of flicker, so it has a good dynamic range also. The BOLT is perfectly suited for quantifying flicker per IEEE and IEC standards.