Tandem connection
In the tandem circuit , two fluorescent lamps are operated in series on a ballast or ballast .
construction
- advantages
- Saving the second throttle
- Reduction of the inductive reactive power
- disadvantage
- When one lamp has burned out, the other flashes or goes out as well.
- Only works up to approx. 2 × 22 W lamps at 230 V mains voltage.
- Since the alternating current flows in the same phase position in both lamps, they do not light up at the same time when the current crosses zero. The result is the stroboscopic effect . A phase shift occurs in the duo circuit , which means that one of the two lamps always emits light.
- The reactive power is less than when two separate standard circuits are operated, but higher than with the dual circuit .
Each lamp has its own starter , which must be a special starter for tandem switching (with a lower ignition voltage than a conventional starter). Examples: Osram ST151, ST172, Sylvania FS − 22, Philips S2, SiS2 and S2 − E. These starters are usually marked with the words “for series connection” or “Series” (English term for series connection).
Normal starters (ST111) are not suitable, as the mains voltage is divided between both (capacitive voltage divider due to the interference suppression capacitors) and these do not ignite at half the mains voltage. A special type for tandem connection must also be used for the choke, so that the rated current is already achieved at a lower choke voltage; their impedance is in the range of a choke for a simple fluorescent tube circuit with the same total output.
literature
- Günter Springer: Expertise in electrical engineering. 18th edition, Verlag Europa-Lehrmittel, Wuppertal 1989, ISBN 3-8085-3018-9