Technical
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Flourescent Lamps

Discharge lamps have to be operated with current-limiting control gear – either conventional, low-loss or electronic.

Conventional Control Gear (CCG)

This is a simple inductive resistor comprised of an iron core around which copper wire is wound. Because of ohmic resistance, there is considerable power loss and thermal output.

Operating modes include operation with glow starters, starter-less operation, and control gear with temperature limitation.

Operation with glow starters

The voltage of the glow starter, in which there is a glow discharge between the bimetallic contacts, is lower than the ignition voltage of the lamp with cold electrodes. When voltage is applied, the glow starter (but not the lamp) ignites. The glow current heats the electrodes, the bimetallic contacts close and the full short-circuit current of the choke flows through the electrodes of the lamp.

As the bimetallic contacts cool, they open. Stored choke energy is discharged, and a voltage pulse is generated to ignite the lamp.

Once the lamp is ignited, only the lamp voltage is applied at the glow starter. This voltage is so low that it cannot cause the glow starter to reignite.

Starter-less operation

While fluorescent lamps connected to a European 230V power supply require simple chokes and an additional preheating transformer or double resonance choke, the voltage for lamps connected to American 120V power supply may be transformed with just two additional heater windings on the current transformer. This involves little additional cost, making starter-less circuits popular in the U.S.

Control gear with temperature limitation

Control gear with temperature limitation helps prevent dangerous overheating as lamps reach the end of their lives. This protection is provided by thermal links.

Electronic Control Gear (ECG)

In contrast to conventional control gear, ECGs operate at frequencies at or above 30kHz, which means they offer significant gains in efficiency. These gains are attributed to a reduction in electrode losses and an increase in luminous efficacy.

The use of modern ECGs has led to significant increases in lighting comfort, economy and reliability.

Lighting comfort

• Flicker-free starting
• Flicker-free light with no stroboscopic effects
• Silent operation with no annoying hum from chokes
• No flashing of faulty lamps
• Automatic restart of replacement lamps
  

Economy

• Up to 30% power input savings compared to CCG operation
• More than 50% longer lamp life compared to CCG or low-loss gear operation
• Low maintenance costs
• Suitable for use in emergency lighting systems to meet VDE 0108 standard
• Reduction in energy costs for air-conditioning systems, reduction in the cooling load
  

Reliability

• Safety shutdown of defective lamps
• Compliance with specific standards for safety and electric/mechanical codes (EMC)
• Protective circuit to guard against transient voltage surges and longer-term overvoltages
  

Dimmable electronic control gear enables compact fluorescent lamps to be dimmed smoothly and without flicker from 100% to 3% luminous flux, and tubular fluorescent lamps from 100% to 1% luminous flux. Control is via an electrically isolated 1-10V interface or a digital addressable lighting interface (DALI).