Waveform of a 750W Mercury Vapor Bulb

[SG-1]

Do you by chance have a regular Merc bulb? You can ballast it with a few incandescents.

That 1 horsepower relic is my only one. If I can get one for under 20 bucks later today though were still in business.

 

[mbrooke]

That 1 horsepower relic is my only one. If I can get one for under 20 bucks later today though were still in business.

Try Lowes- a lot of their HID lamps are now being put on clearance. You could probably score a good quality 175 or 400 watt Sylvania for $5 tops. If not Home Depot might with Philips.

Ie:


https://www.lowes.com/pd/SYLVANIA-ED28-Mercury-Vapor-HID-Light-Bulb/1233925

 

[SG-1]

Try Lowes- a lot of their HID lamps are now being put on clearance. You could probably score a good quality 175 or 400 watt Sylvania for $5 tops. If not Home Depot might with Philips.

Ie:


https://www.lowes.com/pd/SYLVANIA-ED28-Mercury-Vapor-HID-Light-Bulb/1233925

Thanks, will do.

 

[gar]

181101-0851 EDT

SG-1:

Since it appears you have what can probably be used as an isolation transformer for ypur 240 V source change to a 10 A resistive shunt for current measurement. Earth, use EGC, as the point to ground your point between the shunt and the bulb. If your scope is AC powered, then its measurement common is at least indirectly connected to its AC power cord EGC. Thus, should be no conflict between your various grounds. The DC shunt will be probably 50 mV full scale. But you still might use an AC 2 to 3 prong adapter to isolate the scope.

.

 

[gar]

181101-1136 EDT

SG-1:

I have an old clamp-on current transformer from about 1960. I put this on its 12 A range, ranges are 6, 12, 30, 60, 120, and 300.

Using a single burner heating coil, a resistance, 6 A @ 120 V, I saw a left shift of the current zero crossing compared to the voltage of about 1 mS, about 22 electrical degrees. On the 6 A range the shift was much greater, and a distorted waveform. On the 30 A range just a little less than 1 mS.

I believe your current transformer is introducing instrumentation error, and that the current zero crossing is really somewhat shifted to the right of what your plot shows. If the current waveform is shifted to the right some, then the plot zero crossings would make more sense. But then the voltage and current peak values are not aligned. An experiment with your bulb and a DC shunt will clarify what is happening.

.

 

[mbrooke]

Thanks, will do.

:thumbsup:

 

[SG-1]

181101-0851 EDT

SG-1:

Since it appears you have what can probably be used as an isolation transformer for ypur 240 V source change to a 10 A resistive shunt for current measurement. Earth, use EGC, as the point to ground your point between the shunt and the bulb. If your scope is AC powered, then its measurement common is at least indirectly connected to its AC power cord EGC. Thus, should be no conflict between your various grounds. The DC shunt will be probably 50 mV full scale. But you still might use an AC 2 to 3 prong adapter to isolate the scope.

.

The 196C is battery operated & inputs are isolated & rated to 300V. No worries about blowing it up with 240.

 

[peter d]

Were these oddball lamps ever common? :?

 

[SG-1]

181101-1136 EDT

SG-1:

I have an old clamp-on current transformer from about 1960. I put this on its 12 A range, ranges are 6, 12, 30, 60, 120, and 300.

Using a single burner heating coil, a resistance, 6 A @ 120 V, I saw a left shift of the current zero crossing compared to the voltage of about 1 mS, about 22 electrical degrees. On the 6 A range the shift was much greater, and a distorted waveform. On the 30 A range just a little less than 1 mS.

I believe your current transformer is introducing instrumentation error, and that the current zero crossing is really somewhat shifted to the right of what your plot shows. If the current waveform is shifted to the right some, then the plot zero crossings would make more sense. But then the voltage and current peak values are not aligned. An experiment with your bulb and a DC shunt will clarify what is happening.

.

I do not have any current shunts. I will run a couple of tests with resistive heating elements to determine phase shift. I checked the specifications & despite this clamp being a listed accessory for their scopes & power quality meters the 20A scale is unspecified. The 200A scale is unspecified below 10A. May try looping the conductor through it. Have a hall effect clamp that I can try also.

What think ye? Use a circuit breaker in place of the shunt. Perform a fall of potential test across it. Run the expected current through the breaker & measure the voltage across it. Let it sit ten minutes or so & check stability.

 

[gar]

181101-2357 EDT

SG-1:

Make a shunt, but first do a couple tests.

See how much phase shift exists with your present current transformer with a 5 A resistive load. Possibly use a hot plate or twp 250 W bulbs in parallel from a 120 V source as a test resistive load. Possibly you have other resistive loads in your lab.

Do the same test with the Hall current sensor. Should be near zero phase shift.

To make a shunt. I am guessing that your peak current is about 5 A. An 0.1 ohm shunt would produce about 0.5 V. If noise was not too great you could use a lower resistance for the shunt. #16 copper is about 4 ohms per 1000 ft. Thus, 1/40 of 1000 ft is 25 ft. So 25 ft folded back is 12.5 ft. You want the two wires close together to minimuze inductance. So tape the loop together about every 2 ft.

See what happens.

No on the circuit breaker.

You don't need accuracy of current value. So long as the shunt is stable during your experiment yjat should be sufficient.

.

 

[mbrooke]

Were these oddball lamps ever common? :?

Somewhat. GE sold them under the name "E-Z merc" and were offered in the HID section of most major lighting catalogs. The idea was that you could get 16,000 hours of life out of an incandescent socket. Efficiency was only slightly better than incandescent, if that, but 1000 hours vs 16,000 made them a no brainier in post lights and old buildings with incandescent fixtures.

While self ballasted MV is now none existent in the North American and European market for general lighting (for some reason EYE lighting still makes a 120 volt version for the North American market despite LEDs and CFLs :blink self ballasted mercury vapor lamps are extremely popular in Asia and China. They are ballasted with a halogen tube instead of an open filament which allows for higher lumens per watt- coupled with their low initial cost, longer life and sparkling "day" light they are seen as being worth it extensively used in both indoor area and street lighting. Often sold under the name "self ballasted metal halide" which, I can grantee you, certainly are not as there aren't any halogen salts in the arc tube. But the name seems to work in marketing them. :roll:

https://sunlecn.en.made-in-china.co...Self-Ballast-Metal-Halide-Lamps-T-JLZ-T-.html





In the US today self ballasted MV are still used in zoos with reptile exhibits and made such that they will emit UV in addition to light. The UV, warm incandescent glow and blue green of the mercury arc mimic the sun or at least fool the lizards. Of note, because these lamps are intentionally designed emit UV instead of blocking it, they are NOT for general lighting. They can burn skin/eyes over extended periods of time.



https://www.amazon.com/Terra-Solar-...sr=1-13&keywords=self+ballasted+mercury+vapor

https://www.amazon.com/Evergreen-Pe...s&keywords=self+ballasted+mercury+vapor&psc=1

 

[mbrooke]

181101-2357 EDT

SG-1:

Make a shunt, but first do a couple tests.

See how much phase shift exists with your present current transformer with a 5 A resistive load. Possibly use a hot plate or twp 250 W bulbs in parallel from a 120 V source as a test resistive load. Possibly you have other resistive loads in your lab.

Do the same test with the Hall current sensor. Should be near zero phase shift.

To make a shunt. I am guessing that your peak current is about 5 A. An 0.1 ohm shunt would produce about 0.5 V. If noise was not too great you could use a lower resistance for the shunt. #16 copper is about 4 ohms per 1000 ft. Thus, 1/40 of 1000 ft is 25 ft. So 25 ft folded back is 12.5 ft. You want the two wires close together to minimuze inductance. So tape the loop together about every 2 ft.

See what happens.

No on the circuit breaker.

You don't need accuracy of current value. So long as the shunt is stable during your experiment yjat should be sufficient.

.

Honestly, I would pull 2 legs out of the panel and do it that way. Eliminates all error. Here is a person doing something similar but with 230 volt mains:

https://www.youtube.com/watch?v=SDP58iqGNfk


Bulbs are rated 240 volts, if using 120 volt lamps either put them in series or simply except the fact they they will be running at close to 200 volts while the MV lamp is warming up as the resistance is quite low. Once the MV bulb is at full light output, voltage should be roughly even across the arc tube and bulbs if the incandescents are sized close enough. I can post more on this if need be.

 

[gar]

181101-2508 EDT

mbrooke:

Why did you reference the particular link?

Doesn't seem to correlate with your comment. Further it is an extremely poor presentation. This guy has no idea of how formulate and provide a useful presentation.

.

 

[mbrooke]

181101-2508 EDT

mbrooke:

Why did you reference the particular link?

Doesn't seem to correlate with your comment. Further it is an extremely poor presentation. This guy has no idea of how formulate and provide a useful presentation.

.

Its shows the basics, and current during run up indicating a lower impedance arc.

 

[gar]

181102-1026 EDT

mbrooke:

Basics of what?

We have varying series current limiting resistance with time. Not shown. We have varying voltage across the bulb with time, neither averaged or instantaneous. Not shown. We have varying temperature in the bulb. Not shown, We have varying gas pressure in the bulb with time. Not shown. Etc.

.

 

[drcampbell]

... 120 volt versions are a bit more complex, they have filaments in the arc tube (usually at both ends) that branch off from the main electrodes, and are shorted by a bimetal switch that opens when the arc tube heats up. This is to account for the lower starting voltage and work more like a florescent lamp when first switched on. ...

How do the warm-up and hot-restrike times compare for the 120-volt vs. 240-volt bulbs?

 

[peter d]

While self ballasted MV is now none existent in the North American and European market for general lighting (for some reason EYE lighting still makes a 120 volt version for the North American market despite LEDs and CFLs :blink self ballasted mercury vapor lamps are extremely popular in Asia and China. They are ballasted with a halogen tube instead of an open filament which allows for higher lumens per watt- coupled with their low initial cost, longer life and sparkling "day" light they are seen as being worth it extensively used in both indoor area and street lighting. Often sold under the name "self ballasted metal halide" which, I can grantee you, certainly are not as there aren't any halogen salts in the arc tube. But the name seems to work in marketing them. :roll:

Wow, just wow.

 

[SG-1]

Test Results for Fluke i200s Amp Clamp

Test Results for Fluke i200s Amp Clamp

Using resistive heating elements the i200s produced the following results for phase shift.
The 20A scale shows a 6-7 degree shift.
The 200A scale shows a 1-2 degree shift.

 

[SG-1]

Fluke 90i 610 Test results

Fluke 90i 610 Test results

The Fluke 90i 610s Hall Effect Amp Clamp produced a 1 degree shift on the 100A scale (this is the lowest scale).
The resistive elements & set up are also shown.

 

[gar]

181102-2019 EDT

SG-1:

The plots for the Hall probe show a small DC offset upward for the current measurement. The zero crossing shift might be removed if the current probe DC zero offset was removed.

It will be interesting to see the plots for the mercury vapor bulb using the hall probe. Also make a 10 turn coil thru the Hall probe which will make it a 20 A full scale probe.

.