ECN Forum Forums Technical Discussion Electrical Theory and Applications F40 T12 two lamp balast schematic

Scott,
Interesting, what are the typical voltages and currents in this circuit??

GJ

GJ,

These Animals would be used on HO [High Output], VHO [Very High Output], along with the normal Bipin lamps [the lamps with two contacts at each end].

Lamp MA [MilliAmps] would be 430 MA for the normal lamps - sizes F14T12 upto F40T12, with a starting voltage ranging from 100 to 300 volts [depending on lamp type and total number of lamps per ballast]. Fillament voltage ["Heater Windings"] are typically 3.4 - 4.4 volts, but some are as high as 7.5 - 9.0 volts.

For the HO lamps, they would be 800 MA with starting voltages ranging from 80 volts, upto 775 volts.

VHO lamps would be 1,500 MA with starting voltages from 160 to 500 volts.

Fillament voltage on both the HO and VHO lamps is 3.4 to 4.5 volts.

HO and VHO lamps are generally the 8 foot'ers, but they also come in 4 foot and 6 foot sizes. Think I have even seen 2 foot and 3 foot lamps in HO, but not in VHO.

FYI: The highest voltage from these ballasts would be the starting voltage. Once the Arc is established, voltage drops very low and the whole thing is based on limiting the current flowing through the lamp to a level which will be useful and not destroy the lamp. No Ballast in series with the lamp - lamp tries to draw every bit 'O current it can get [which quickly destroys the lamp! Suicidal Lamp Tendencies ... no relationship to the band ].

Heater Windings' job is to continuously keep the fillaments [or Cathodes if you prefer] warm during lamp operation - even after the lamp has started. This makes them Hot Cathode, rather than Cold Cathode operation.

Scott SET

thanks Scott,

GJ