gibbothegreat Posted November 25, 2016 Share Posted November 25, 2016 Hi folks, we own 3 Desisti/Robert Juliat 5k fresnels which can be converted to HMI, and we're using two of them in the latter mode for our Christmas show. We're having something of a problem with the ballasts, in that they frequently trip the breaker for the 32a supply on striking up. The ballasts are Robert Juliat model A4/2500 and I gather that these units are pretty old. Is this a known issue at all (couldn't find anything with searches)? And if so, is there a fix, or a replacement ballast? Thanks in advance, GTG Link to comment Share on other sites More sharing options...
adam2 Posted November 25, 2016 Share Posted November 25, 2016 How many ballasts on a 32 amp circuit, and if more than one, are you striking them all at once or in rotation. Link to comment Share on other sites More sharing options...
Stuart91 Posted November 26, 2016 Share Posted November 26, 2016 Is the breaker on the supply a B-type, or C-type? Link to comment Share on other sites More sharing options...
Whiskers Posted November 26, 2016 Share Posted November 26, 2016 Are the ballasts electronic or wire wound? running as 4 or 2.5? Link to comment Share on other sites More sharing options...
Mr Steve Posted November 26, 2016 Share Posted November 26, 2016 As Stuart91 says, check the breakers to see if they are B, C or even D. The inrush current on strike may trip a B breaker. Link to comment Share on other sites More sharing options...
Whiskers Posted November 26, 2016 Share Posted November 26, 2016 HMIs use more power that the lamp is rated for typ 4K = 21A running current at 230V Igniter pulse is not a lot so do not worry there. If the ballast is a cheapo and has no PFCs then add 50% to all currentsLikewise if the ballast is old and the PFCs have dried up then + 50% A rough test for old capacitors is clip on meter on the leads, they should show substantial current 5 to10A (this is subtracted at right angles from the total amps) There are usually several paralleled Cs so you can check with a clip on at various points on the chain and arithmetic which are working. Do be very careful inside a ballast, dangerous and expensive, also usual HMI warnings, full of hard UV turn of immediate if lens is damaged, strike voltage can be 70,000 volts. For magnetic ballasts there is also a + 50% current during the warm up phase, electronic ballasts should correct this. So worst case for a 4K on 230v with a magnetic and no PFC A x PFC? x Start up => 21A x 1.5 x 1.5 = 47.5 AScale for other size HMIs As the warm up is 2 mins then sequence starting will not help, a good clip on will help you understand what is flowing. Link to comment Share on other sites More sharing options...
gibbothegreat Posted November 28, 2016 Author Share Posted November 28, 2016 How many ballasts on a 32 amp circuit, and if more than one, are you striking them all at once or in rotation. All on individuals Are the ballasts electronic or wire wound? running as 4 or 2.5? Not sure, and 2.5 Link to comment Share on other sites More sharing options...
Whiskers Posted November 28, 2016 Share Posted November 28, 2016 Electronic ones often match more than one power so will run 2.5 / 4 kW or 1200W / 2.5 kW so have 2 different outlets Electronic ones probably have LCD display / LEDs Magnetics are incredibly heavy - indicators probably neon Post a picture if you can Do the MCBs trip at the moment of strike or after a short time? Can you measure the running current on a good strike If it is marginal an extra 20M of cable might reduce inrush, Link to comment Share on other sites More sharing options...
gibbothegreat Posted December 5, 2016 Author Share Posted December 5, 2016 Thanks all for helpful info (and apologies for the time taken to say so, opening the Xmas show rather got in the way...) Link to comment Share on other sites More sharing options...
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