Transformers for low-voltage halogen lamps

FAQ: Frequently asked questions


  1. What is the maximum permitted cable length for electronic HF transformers?
    • The maximum permitted cable length between the lamp and the HF transformer is limited by the skin effect. For information on the cable length see the data sheet.
  2. What is the operating frequency of electronic transformers?
    • The output frequency is between a minimum of 35 kHz and a maximum of 70 kHz depending on the device.
  3. Is the output voltage of electronic transformers stabilised?
    • The output voltage is specified at 11.5 V.
  4. What is the maximum switch-on current for an electronic transformer?
    • The maximum switch-on current for an electronic transformer is defined by the maximum current that the device can take on the primary side.
  5. How can a Tridonic transformer be dimmed?
    • TE one4all transformers can be controlled with DSI, DALI and switchDIM. The signals that can be used to dim the individual types are given in the relevant data sheets.
  6. What operating modes are recommended when using phase dimmers?
    • With leading-edge phase control the current is switched on with a delay after the zero crossing point of the ac voltage and is applied until the next zero crossing point, whereas with trailing-edge phase dimming the situation is precisely the reverse: the current is switched on immediately after the zero crossing point and switched off before the next zero crossing point.

      Leading-edge phase control is not suitable for capacitive loads because of the sudden voltage rise (an extremely high current would flow); trailing-edge phase control is used here instead. On the other hand, trailing-edge phase control is not suitable for inductive loads (voltage peak when the current is switched off).

  7. How can magnetic transformers be dimmed?
    • Magnetic transformers are dimmable. We recommend leading-edge phase control.
  8. What function does the current guard perform in TE-DC 2?
    • Current guards, also known as current monitors, protect low-voltage installations against overheating in the event of a short-circuit. Current guards detect any change greater than 40 W and switch off the transformer. In the as-delivered state the current guard is not active and must be activated.
  9. With regard to the TE-DC 2 transformer Tridonic specifies a cable length of 20 m on the lamp side in the data sheet, which is much more than is usual with other electronic transformers. Why?
    • The TE-DC 2 filters out all HF components at the output so the skin effect has no influence here.
  10. Why does the data sheet indicate a minimum load?
    • A minimum load is needed because electronic transformers are what are known as self-oscillating circuits. Resonance oscillations may occur, which is why a minimum load is necessary.
  11. Is DC operation in accordance with EN 50172 possible?
    • All the devices specified with EN 50172 can continue to be operated on a DC power supply if the ac power supply fails, so they can also be used for emergency lighting.
  12. Are transformers with a zeroing system compatible with PEN cables?
    • Electronic transformers can be used on zeroes systems without restriction.
  13. I want to use a TE transformer to operate LED modules. Is that OK?
    • LEDs cannot be operated with TE transformers.
  14. Is it possible for electronic transformers to cause faults in merchandise security systems?
    • Because of the operating frequency of 35–70 kHz there is a possibility of interference with merchandise security systems.
  15. Which electronic transformers have the corridorFUNCTION?
    • TE one4all and TE-DC 2. The product features are given in the relevant data sheets.
  16. Can TE-T and TE one4all be operated in an installation?
    • No.
      TE-T and TE one4all cannot be operated via the same switch circuit.