Hello all,
   I am a maintenance tech for a plastic packaging company and our Printers use UV Curing for the inks and I have a system that uses
Parmar Parry UV Ballasts that are 4000 watt and 460/480 volt and I was hoping that someone in the forum could help me with some
info on testing these ballasts. Is there a way to use OHMS/Mega ohms, Volts, Amps, to test whether these ballast are good? Sometimes
we have UV issues and since we do not have a good supply of these it is hard to tell if they are failing. Can anyone suggest a test
method? Thanks much and have a great day.
                Best Regards,
                     Ross

You can test for continuity of the windings using an ohm meter between 1-2 and 1-3 to check both voltage tappings, which should confirm continuity of the coil.
Also then test with an insulation resistance tester (megger etc.) between the ballast terminals and earth (base plate/ballast core) to check for and leakage down to earth.
That should at least confirm they have continuity and the insulation isn't broken down.

If there are issues with the lamps striking then it could be an ignitor problem rather than the ballast.
Hope this helps

As far as I know, I believe some UV lamps have a very similar form factor and electrical characteristics to fluorescent tubes. This means that you might be able to use fluorescent tubes to test certain UV ballasts.

I would like to see this Mythical 4000W fluorescent tube your alluding to with that sort of post! you would certainly not want to use any sort of flourcent tube with the system the original poster has, that quite a dangerous suggestion to make given the gross overload it would be for any sort of fluorescent tube



as for the original posters issue, as Beta 5 says at the end of his post if your having issues with the UV systems in your industrial equipment, I would look at the lamp ignitors and make sure that they themselves are functioning, discharge lamp ignitors are much more prone to failure then a simple choke ballast like that Parmar unit is, so the ignitors is where I would start

As far as original poster mentioned printing curing, probably specialty overgrown metal halide arc lamps are involved. Depending on the wavelength the process requires, filled with indium, gallium, or more exotically, iron, lead or cobalt iodides. It would be nice to get a hint what ballast schematic is involved, but my first approach would be to measure lamp current with a good quality clamp meter. Comparing lamp current between good known working units and faulty ones will give the idea. If the current is OK, the problem will be definitely not within the ballasts. Next the failure can be traced further. If you say ballasts are used in 3-packs parallel, you can measure the the current in all three circuit branches to check if any choke is open/abnormal. Non-contact clamp meter is recommended because of lethal voltage levels in use, and ease of getting a measurement.

Also, AFAIK, such kinds of lamps, especially gallium filled, have rather finite life. As the lamp blackens, UV output drops and not much can be done beyond lamp replacement. There seems still to be some companies offering such lamps, even made to order, in the west and in China.

For isolated test of a single ballast choke I would recommend just connecting pins 1-3 (480V voltage) of the ballast across 230V (or 120V) power line and measure the current. You will likely get something in 5-10A range. Again compare the current between a known good choke and a suspected one.


I assume the circuit schematics is just a choke (3x parallel) and a superimposed ignitor. Use 16A circuit breaker in series to avoid fireworks when doing this test. The inductance of the winding can be measured as well with an inductance meter, but practice shows the measuring the inductance of iron cored ballast chokes at low power level sometimes gives gross errors even with okay units, due to iron core non-linearity and magnetization.

I would like to see this Mythical 4000W fluorescent tube your alluding to with that sort of post! you would certainly not want to use any sort of flourcent tube with the system the original poster has, that quite a dangerous suggestion to make given the gross overload it would be for any sort of fluorescent tube



as for the original posters issue, as Beta 5 says at the end of his post if your having issues with the UV systems in your industrial equipment, I would look at the lamp ignitors and make sure that they themselves are functioning, discharge lamp ignitors are much more prone to failure then a simple choke ballast like that Parmar unit is, so the ignitors is where I would start

I must have missed the fact that the post was pertaining to the 4000W lamp, but I was just taking note of some types of germicidal lamps. I certainly understand that 4000W ballasts would definitely kill fluorescent tubes for sure. I just might have not been paying attention here. I originally thought that it mainly had to do with any type of germicidal ballast in general. I sometimes have missed certain points of information without even realizing. I did mean to say that only SOME germicidal lamps had a similar form factor to fluorescent tubes. I did NOT say that ALL UV lamps had a form factor similar to fluorescent tubes. I have also been trying to modify my statements lately so that they are not absolute statements.

And of course the first and simplest test on such chokes is to measure DC resistance. I would expect something in the range of about one ohm. Measurement  between different units shall agree to at least 20%, assuming the same series and temperature. But beware of contact resistance at the multimeter probe ends, it may vary. Open winding or kiloohm reading will definitely mean a faulty choke.

Cedric, if you don't know about something, please don't comment on it, 4000 watt fluorescent tubes do not exist! Testing a fluorescent tube on this ballast would destroy the tube very quickly!

Hello Beta 5,
   Thanks so much for the good info and I will check the ohms and mega ohms as you suggested
and I am thinking that you are correct about the ignitors being a possibility as we have replaced
a few over the years but have only lost on Ballast due to bad terminal connections melt down the terminals.
Thanks again and have a great new week.
             Best Regards,
                  Ross

 

Hello RKK,
   Thanks so much for your reply and I have attached the schematic for our system
that was originally manufactured by Nordson over twenty years ago. I believe that
the bulbs are listed as Medium Pressure mercury bulbs and these bulbs are rated for
1000 hrs of usable light and they do get dark on the ends after many hours of use.
Hope this helps. Thanks again for all your help and I wish you a great week.
          Best Regards,
               Ross

Hello! Thanks for schematics. Power path with a lamp looks pretty standard and understandable, though the amount of relay logic used to run just a single lamp looks a bit excessive.

In your schematics, lamp is connected between two phases of 480V feed. Contactor CON2 is used to connect lamp to the power. By default, ballast consist of two chokes, 1KW and 2KW. By closing a contactor CON4, additional third 2KW choke is connected.

Schematics of the control is somewhat inconsistent with power path schematics, as it mentions contactor CON3 which is not present on the power path schematics.

What is the problem you are experiencing? It seems that control cabinet already includes an ampermeter to check lamp current. That way, if amp reading is OK, but UV is low, almost certain the lamp is just aged and is dropping UV output. If amp reading is low, then again lamp may be aged and increased its working voltage, causing the current to drop, or you may have one of the chokes open, or a faulty contactor that does not close, or faulty relay logic that does not energize one of the contactors.

If the lamp does not start, and does not even flicker, you should check that at least contactor CON2 is closing, chokes are not open, and that starter (ignitor) is OK and generates high voltage pulses. Of course, lamp at end of life may just refuse to ignite.

 

Also isn't there some troubleshooting manual for the machine? Something that would be listing what voltages should be present at key places and when? Mainly expected arc voltage drop would help to asses whether the wrong current is due to the lamp or ballast.

What is good there are actually 3 ballast chokes with known contribution of each, so if the lamp lights somewhat, just comparing the currents ("2kW" choke should pass twice as much current as the "1kW") will give very good info about the chokes health (it is extremely unlikely more than one would be faulty in a way the current ratio remains the same).

I may imagine the complex logic is related to the safety of personell, but also the equipment and the workpiece, so failure of some stupid small part won't cascade into a big disaster. We are talking about few 100's W of UV and few kW of heat here, it is way too potent to cause mayhem when unchecked...