Technical Application Knowledge: From practice, for practice
Before the introduction of LED lighting, both leading and trailing edge dimming were dimming technologies frequently used in residential lighting applications. Special leading or trailing edge (phase-cut) dimmers enabled excellent control of the luminous flux of connected lamp(s) even at low dimming levels – without the need for extra wiring, usually via a rotary switch installed on the wall. The dimmer cuts off the variable part of the leading or trailing sine-shaped waveform of the mains supply in order to dim the luminous flux from 3-5 % to even 100 % (the exact value depends on the corresponding dimmer type, the driver, and the LED technology used).
There are two different types of phase-cut dimming which are distinguished by how the mains voltage is cut off:
- Leading edge dimming: The wave of the AC mains voltage is cut off on the leading edge, from the beginning. This dimming technology is traditionally used for halogen lamps supplied via electromagnetic transformers.
- Trailing edge dimming: The wave of the AC mains voltage is cut off on the trailing edge, backwards from the end. The advantage of this dimming type is that less interference occurs than with leading edge dimming.
Dimmers and related components can either support leading or trailing edge dimming, or even both phase-cut dimming types.
OPTOTRONIC OT FIT drivers for leading and trailing edge dimming, 24 V DC constant voltage, are simply perfect for the phase-cut dimming control of 24 V constant-voltage solutions.
These drivers are compatible with existing 24 V DC constant-voltage lighting solutions from OSRAM Digital Systems and provide several features:
- SELV
- Wide temperature range: Ta from -20 to +50 °C
- Up to 50,000 hours lifetime at Tc max
- Dimming range: from 3 to 100 % of the luminous flux
- IP20 rating
- High luminous efficacy and very stable output power
- High reversible short-circuit, overload, and overtemperature protection
It is recommended to combine OT FIT 24 V DC PC drivers with trailing edge dimmers. A large number of different dimmers have been tested during product development.
The OT FIT 24 V DC PC product range is available in three different power levels:
- 36 W: OT FIT 36 /220-240/24 PC (EAN 10: 4062172237390)
- 75 W: OT FIT 75 /220-240/24 PC (EAN 10: 4062172237413)
- 150 W: OT FIT 150 /220-240/24 PC (EAN 10: 4062172237642)
These drivers are ideal for the following applications:
- Integration into 24 V luminaires, protection classes I and II
- Suitable for hospitality applications, especially decorative lighting and/or lighting during night-time hours
- Decorative lighting in restaurants
- Decorative lighting and shelf lighting in shops
- Residential applications, especially for floor-standing luminaires or as under-cabinet lighting
