Why the american ballasts hums also when the lamp extingushed « on: January 30, 2015, 01:00:43 PM » Author: dor123
I've observed several videos of american HPS lamps on american ballasts in Youtube, that the user also did a hot restrike, and noticed that the ballast continue to hum, even when the main discharge extingushed and only the glow from the ignitor presents (Unlike our chokes, which hums only with the presence of the main discharge). I've also seen a video of a hot restriking probe-start MH lamp, on an american ballast, and the ballast hum, when the aux discharge appears, what isn't happens with our chokes and MV lamps. How the american ballasts can hum, also when the lamp gets voltage but is extingushed, and our choke don't?
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	Re: Why the american ballasts hums also when the lamp extingushed « Reply #2 on: January 30, 2015, 04:13:06 PM » Author: dor123
I thought about this before, but wasn't sure.
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	Re: Why the american ballasts hums also when the lamp extingushed « Reply #3 on: January 31, 2015, 02:31:18 AM » Author: Medved
@sol: It is not just "maybe", it really is that. The connected primary means magnetic flux and the magnetic flux means hum...
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	Re: Why the american ballasts hums also when the lamp extingushed « Reply #4 on: February 08, 2015, 02:31:14 AM » Author: RyanF40T12
Humming is goooooooood. https://www.youtube.com/watch?v=BEm0AjTbsac
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	Re: Why the american ballasts hums also when the lamp extingushed « Reply #6 on: April 08, 2015, 04:20:32 PM » Author: icefoglights
Even on choke ballasts will hum (more of a buzz) while waiting to re strike.  The buzz can be louder than the hum when it's normally lit.
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	Re: Why the american ballasts hums also when the lamp extingushed « Reply #7 on: April 08, 2015, 11:43:25 PM » Author: Medved
Quote from: icefoglights on April 08, 2015, 04:20:32 PM Even on choke ballasts will hum (more of a buzz) while waiting to re strike.  The buzz can be louder than the hum when it's normally lit. I guess you are talking about HPS or other pulse start lamp.  That buzz is coming from the ignitor activity (the ignitor uses the choke as a step up pulse transformer, those pulses repeated at usually twice the mains frequency then make the buzz)
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	Re: Why the american ballasts hums also when the lamp extingushed « Reply #8 on: April 09, 2015, 02:22:25 AM » Author: dor123
If the ignitor is semi-parallel, the ballast makes the buzzing (Or the clicking, if the ignitor is low frequency pulses). If the ignitor is superimposed, the ignitor make it. With internal starter HPS lamp, the choke ballast will hum as long as the starter shorting it (Not different than a fluorescent choke + glow starter).
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Please forgive me if my choice of my words looks like offensive, while that isn't my intention.

I only working with the international date format (dd.mm.yyyy).

I lives in Israel, which is a 220-240V, 50hz country.

	Re: Why the american ballasts hums also when the lamp extingushed « Reply #9 on: May 08, 2015, 08:54:14 AM » Author: Solanaceae
Mercury chokes also do this since they're connect to L&N.
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	Re: Why the american ballasts hums also when the lamp extingushed « Reply #10 on: May 08, 2015, 10:44:02 AM » Author: Medved
Quote from: Solanaceae on May 08, 2015, 08:54:14 AM Mercury chokes also do this since they're connect to L&N. In the US most of the ballasts do hum, as (except the low wattage HPS) all are some sort of a transformer. And that means field present when the mains connected, so the hum. Most of the European ballasts (all except higher power LPS) are just of a series reactor type, there without the igniter pulsing is no current, so no field to hum without the lamp. Of course, the same is valid for the US low power HPS with just the series reactor ballasts. When operating (with the lamp lit), the loudest are ballast designs involving saturation of the core, so the CWA in the US and some series chokes during run up and some even during normal operation (mainly HPS - as the saturation is utilized to boost the current for a cold lamp and then stabilize the arctube temperature)...
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	Re: Why the american ballasts hums also when the lamp extingushed « Reply #11 on: May 17, 2015, 02:10:46 AM » Author: Solanaceae
Quote from: Medved on May 08, 2015, 10:44:02 AM Quote from: Solanaceae on May 08, 2015, 08:54:14 AM Mercury chokes also do this since they're connect to L&N. In the US most of the ballasts do hum, as (except the low wattage HPS) all are some sort of a transformer. And that means field present when the mains connected, so the hum. what is the wattage rang for the HPS ballasts? My dinky little 100w keystone HPS ballast doesn't make a peep with power connected and on or even when the bulb is missing. However, my 70w HPS security lite on my deck makes a humming from the ballast and a more noticeable zapping noise from the igniter.
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	Re: Why the american ballasts hums also when the lamp extingushed « Reply #12 on: May 17, 2015, 05:32:16 AM » Author: Medved
The S55 and all lower wattages are just a series choke, so the only noise source there is the ignitor (just the ignitor pulses). The S56 and all wattages above use some kind of transformer ballast, so those may hum even without the ignitor (the 60Hz magnetic field plus the ignitor pulses). The ignitor may contain some sort of cut out designed to prevent the EOL lamps from cycling, so it may stop causing any noise after some time. But even when there is something that could cause some noise, it could well be, that noise is actually so low, you do not notice it. That could be the case for both 60Hz, as well as the ighitor pulse noise. Mainly the second would be negligible, when the coil itself is well made (tight, well impregnated, so the wires are fixed and can not move; or tidily wound, so the spikish field is distributed over larger area), as the narrow pulses do not create any significant field in the core.
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	Re: Why the american ballasts hums also when the lamp extingushed « Reply #13 on: May 18, 2015, 07:49:25 AM » Author: Solanaceae
Some of the newer electronic ballasts for fluorescent bulbs  don't hum per se, but they emit a high screeching noise when the lamp is taken out. It's mainly the sylvania quicktronic or keystone electronic ballasts out of under cabinet fittings.
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	Re: Why the american ballasts hums also when the lamp extingushed « Reply #14 on: May 18, 2015, 03:53:09 PM » Author: Medved
Quote from: Solanaceae on May 18, 2015, 07:49:25 AM Some of the newer electronic ballasts for fluorescent bulbs  don't hum per se, but they emit a high screeching noise when the lamp is taken out. It's mainly the sylvania quicktronic or keystone electronic ballasts out of under cabinet fittings. The main operating frequency won't be ever audible, but the circuits could enter subharmonic oscillations, so the main operation becomes modulated by a fraction of the main frequency and that fraction may fall into an audible range, audible as those squeaking. Sometimes it uses to be the PFC stage becoming unstable when the load is removed (the PFC is hiccuping on the output overvoltage protection comparator and it takes some time for the loop to settle). Other cause is subharmonic oscillations, when the main chokes start to saturate. Sometimes it is heard from the CFL's, when they are just failing (usually the squeak ends as a bang or a cloud of smoke, sometimes even peacefuly).
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