Author Topic: Correct inductance of choke for running a 40w T12 on 220-240v mains?  (Read 1348 times)
Laurens
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Correct inductance of choke for running a 40w T12 on 220-240v mains? « on: February 03, 2024, 10:23:58 AM » Author: Laurens
I have a plethora of inductors and chokes sitting around. But barely any 'official' fluorescent ballast chokes.

There's nothing that special about a choke for a fluorescent lamp, any inductor with the right power handling capability and inductance will do.

So does anyone have a list of how many Henry each type of magnetic ballast is? That way i can figure out if i can use certain transformer primaries with different taps as a magnetic ballast for tubes i don't have a 'proper' ballast for. Hell, i could even use a variac wired up as as a 'normal' inductor for setting exactly the right inductance.

Related: the correct running voltage and current for a 40w t12 is also welcome :)

Also related: the picture below.
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RRK
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Re: Correct inductance of choke for running a 40w T12 on 220-240v mains? « Reply #1 on: February 03, 2024, 12:00:28 PM » Author: RRK
Here is the reference data from an old Soviet book. In Russian, but pretty understandable. Left table is the reference for lamps, fluorescent and mercury (1970's data, but not much changed since) right table is the data for 'reference' low loss measurement chokes. Columns are Lamp power - Impedance - Nominal current - Power factor (only choke itself). Note that first two chokes are tabulated for 127V line voltage. Modern 18 and 36W tubes run on 20 and 40W ballast impedances, too.

Knowing an impedance, you can easily calculate the inductance.  The aim is to get the right lamp current, and to verify it with an ampermeter. Remember, as tube voltage is non-sinewave, simple circuit theory gives only approximate results, exact formulas are rather bulky.
« Last Edit: February 03, 2024, 12:06:02 PM by RRK » Logged
Laurens
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Re: Correct inductance of choke for running a 40w T12 on 220-240v mains? « Reply #2 on: February 03, 2024, 12:14:19 PM » Author: Laurens
Thanks, this is very useful! Engineering is an international language, although i can't speak russian, i can transliterate cyrillic a bit to make sense of datasheets.
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WorldwideHIDCollectorUSA
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Worldwide HIDCollectorUSA
Re: Correct inductance of choke for running a 40w T12 on 220-240v mains? « Reply #3 on: February 03, 2024, 11:58:34 PM » Author: WorldwideHIDCollectorUSA
For virtually all 4 foot 40W T12 fluorescent tubes in the world, the arc voltage drop is about 100V while the operating current is about 430mA.
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Desire to collect various light bulbs (especially HID), control gear, and fixtures from around the world.

DISCLAIMER: THE EXPERIMENTS THAT I CONDUCT INVOLVING UNUSUAL LAMP/BALLAST COMBINATIONS SHOULD NOT BE ATTEMPTED UNLESS YOU HAVE THE PROPER KNOWLEDGE. I AM NOT RESPONSIBLE FOR ANY INJURIES.

WorldwideHIDCollectorUSA
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Worldwide HIDCollectorUSA
Re: Correct inductance of choke for running a 40w T12 on 220-240v mains? « Reply #4 on: February 04, 2024, 02:09:36 AM » Author: WorldwideHIDCollectorUSA
Thanks, this is very useful! Engineering is an international language, although i can't speak russian, i can transliterate cyrillic a bit to make sense of datasheets.

I also recommend using Google Translate to be able to read the document in your native language. I often use google translate to read Japanese lighting documents in English.
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Desire to collect various light bulbs (especially HID), control gear, and fixtures from around the world.

DISCLAIMER: THE EXPERIMENTS THAT I CONDUCT INVOLVING UNUSUAL LAMP/BALLAST COMBINATIONS SHOULD NOT BE ATTEMPTED UNLESS YOU HAVE THE PROPER KNOWLEDGE. I AM NOT RESPONSIBLE FOR ANY INJURIES.

Mandolin Girl
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Re: Correct inductance of choke for running a 40w T12 on 220-240v mains? « Reply #5 on: February 04, 2024, 07:56:31 AM » Author: Mandolin Girl
*Other translations websites are available.  :wndr:
We won't touch anything associated with Google because they'll track you to within an inch of your life if they can.  :curse:
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RRK
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Re: Correct inductance of choke for running a 40w T12 on 220-240v mains? « Reply #6 on: February 04, 2024, 12:24:34 PM » Author: RRK
Just use a separate Firefox profile and clear cookies and cache before and after. Google will not have a chance to link your request to your other web activity. Until your browser or your provider do not forcibly insert an 'advertising id' cookie. Likely not practiced outside mobile networks and outside US and probably a violation of GDPR in Europe.

I too do not like that 'metadata hoover' behavior of Google though most people do not care...
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ultralume
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Re: Correct inductance of choke for running a 40w T12 on 220-240v mains? « Reply #7 on: July 14, 2024, 11:41:47 PM » Author: ultralume
Looking over the Russian data sheet, I compared the
Specifications of a 400 Watt mercury lamp against the ANSI C.78 standards and to no surprise, the specifications are the same. Lamp current listed as 3.2 Amps (ANSI) vs. Russian 3.25 Amps. Choke ballast impedance of 44.8 Ohms (ANSI) vs. 45 Ohms (Russian), nominal operating voltage of 135V. Furthermore the lamps are listed as having a power factor of 0.075 in both the ANSI and Russian standards. What does a lamp Power Factor of 0.075 mean? A choke or high reactance (leakage) auto transformer has a PF around 0.50, which I understand is the ratio of real power vs apparent power.  The relationship between real, apparent and reactive power can be represented as a right triangle. Does such relationship apply to a mercury vapor lamp? Does a gas discharge really have such a low power factor?
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WorldwideHIDCollectorUSA
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Worldwide HIDCollectorUSA
Re: Correct inductance of choke for running a 40w T12 on 220-240v mains? « Reply #8 on: July 14, 2024, 11:45:23 PM » Author: WorldwideHIDCollectorUSA
I have also been aware that the 3.25A specification for 400W mercury vapor lamps has also been the same in virtually all countries on the planet including that of Japan.
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Desire to collect various light bulbs (especially HID), control gear, and fixtures from around the world.

DISCLAIMER: THE EXPERIMENTS THAT I CONDUCT INVOLVING UNUSUAL LAMP/BALLAST COMBINATIONS SHOULD NOT BE ATTEMPTED UNLESS YOU HAVE THE PROPER KNOWLEDGE. I AM NOT RESPONSIBLE FOR ANY INJURIES.

ultralume
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Re: Correct inductance of choke for running a 40w T12 on 220-240v mains? « Reply #9 on: July 14, 2024, 11:54:27 PM » Author: ultralume
One ballast manufacturer actually lists the value of the choke ballast and the reactive voltage component (which can be multiplied by lamp current of 3.25 amps to yield the reactive power in Watts). I actually measure 192 V across the choke with 3.2-3.3 amps. Choke value is 155 mH for 60 Hz operation.



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RRK
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Re: Correct inductance of choke for running a 40w T12 on 220-240v mains? « Reply #10 on: July 15, 2024, 02:16:50 AM » Author: RRK
Looking over the Russian data sheet, I compared the
Specifications of a 400 Watt mercury lamp against the ANSI C.78 standards and to no surprise, the specifications are the same. Lamp current listed as 3.2 Amps (ANSI) vs. Russian 3.25 Amps. Choke ballast impedance of 44.8 Ohms (ANSI) vs. 45 Ohms (Russian), nominal operating voltage of 135V. Furthermore the lamps are listed as having a power factor of 0.075 in both the ANSI and Russian standards. What does a lamp Power Factor of 0.075 mean? A choke or high reactance (leakage) auto transformer has a PF around 0.50, which I understand is the ratio of real power vs apparent power.  The relationship between real, apparent and reactive power can be represented as a right triangle. Does such relationship apply to a mercury vapor lamp? Does a gas discharge really have such a low power factor?

Are you sure 0.075 PF is quoted for the lamp and not for a reference 'nominal' ballast? The lamp itself has its own 'power factor' in the range of 0.9-0.95 approximately, but it is not a 'linear' PF because of phase shift, and is more a reflection of the fact that for a discharge lamp Urms*Irms is not equal to lamp power, mainly because lamp voltage is not sinewave.
« Last Edit: July 15, 2024, 02:19:44 AM by RRK » Logged
ultralume
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Re: Correct inductance of choke for running a 40w T12 on 220-240v mains? « Reply #11 on: July 15, 2024, 07:13:04 AM » Author: ultralume
RRK.. you are correct. I misread /misunderstood the  data sheets. The PF of 0.075 listed is indeed for the reference ballast and not the lamp. If I understand correctly, the overall PF of an operational circuit with a fully warmed up lamp is appproximately 0.50. The reference choke itself has  PF of 0.075. Is that what would be measured in the event the lamp shorted out in the circuit?
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RRK
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Re: Correct inductance of choke for running a 40w T12 on 220-240v mains? « Reply #12 on: July 15, 2024, 12:35:55 PM » Author: RRK
I think the value PF of 0.075 is not get measured, and is a classification of a nominal ballast choke. Any reasonable choke has a combination of an active and inductive resistance, and since a lamp behavior is slightly different on active (resistive) and inductive ballast, they probably use that PF value to describe some standard (reference) ratio for a nominal choke. Note that the table from a Russian book I put here describes some special expensive kind of ballasts, intended for lamp measurement, having more precisely defined impedance, and likely lower drift because of lower heating/power losses than a regular 'lighting' usage ballasts.

And yes, typical discharge lamp circuits have PF of 0.4-0.5, because it is usually practical to have a line voltage about double of discharge voltage to get good stability, while still having reasonable ballast losses. Some other variants like single 20W tube on 230V line behave worse.
 
« Last Edit: July 15, 2024, 12:54:22 PM by RRK » Logged
ultralume
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Re: Correct inductance of choke for running a 40w T12 on 220-240v mains? « Reply #13 on: July 16, 2024, 11:59:55 PM » Author: ultralume
RRK, I thank you for your explanation. I multiplied the impedance value of the ballast, 45 Ohms by 0.075 and got 3.4 Ohms. I measured the resistance of the choke and got 3.3 - 3.4 Ohms,
Which agrees with the calculated value..
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