Low-voltage halogen lamps need to be operated on transformers. Transformers are devices that transform voltage. Those used in lighting installations convert 230 V line voltage into an extra-low voltage – normally 12 V but sometimes 6 or 24 V.

Electronic transformers

Transformers come in conventional and electronic designs. As in the case of ballasts, modern electronics helps save energy and offers greater lighting comfort. What is more, electronic transformers (ET) are smaller, more compact and quieter than conventional transformers.

From a functional viewpoint, they are similar to electronic ballasts (EBs). Their advantages at a glance:

• low power dissipation (two-thirds less than conventional transformers)
• no transformer "hum"
• high efficiency
• overload and overheating prevented by adaptive power control
• reduced heat generation
• soft start – no current surge on activation
• gentle operation for longer lamp life
• electronic protection against short-circuiting
• non-encapsulated, therefore repairable if defective
• compact design and low weight
• ETs also operate on direct voltage, which makes them suitable for emergency lighting.
  
  

Conventional transformers

Conventional transformer technology works with different primary-side (line voltage) and secondary-side (low voltage) windings. Transformers need to be fused on the primary side. Safety transformers according to DIN EN 60742 prevent line voltage spilling over to the low voltage installation in the event of a fault.

Thermal protectors known as thermal cutouts make for added safety. When tripped by overheating, they disconnect the power supply until the primary-side winding has cooled sufficiently.

Conventional transformers are relatively power-hungry, so they should be replaced by electronic transformers.