5

1.3 Ignition and re-ignition

In the case of electromagnetic control gear, a combination of preheating and a high ignition peak is obtained by using a normal choke ballast and a preheat starter or an electronic ignitor.

Energy is supplied to the discharge in the form of electrons.The lamp current, just like the mains voltage, is sinusoidal, with a frequency of

50 or 60 Hz. If the energy flow is zero (at lamp current reversal) the lamp stops burning and in theory would have to be re-ignited.

This could be done by supplying additional energy to the electrodes via a higher lamp voltage, the way it is done when initially starting the lamp. But from the moment the lamp has reached its stationary condition, the lamp voltage is constant.

And yet, in practice the lamp does not extinguish at current reversal. Why not?

The phase shift introduced by the inductive element of the ballast ensures that the mains voltage is not zero at that moment. Because of the inductive properties of choke coil ballasts a phase shift ϕ occurs between the mains voltage and the lamp current (see Fig. 102). So, at the moment of current reversal the lamp voltage would be equal to the mains voltage, since the voltage over the ballast is nil.The difference (gap) between the mains voltage and the average lamp voltage as a consequence of the phase shift ensures proper re-ignition of the lamp at the moment the current passes the point of reversal (zero-point A in figure).

Fig. 102. Phase shift between supply voltage and lamp current (and lamp voltage) in a

V, A

gap

Vm

Il

Vl

t

discharge lamp with an inductive ballast. In the case shown, the supply voltage is sufficiently high for re-igniting the lamp after ever y current reversal.

ϕ

A

1 4 Types of ballasts

1 Resistor ballasts

Current limitation by means of resistor ballasts is a very uneconomic form of current limitation, because in the resistor electrical energy is dissipated in the form of heat. Nevertheless, until the advent of electronic circuitry, use of a series resistor was the only way of stabilising fluorescent lamps operated on DC, for example the ‘TL’R lamp (see Fig. 103). For stable operation on a resistor ballast, it is necessary that the supply voltage be at least twice the lamp voltage under operating conditions.This means that 50 per cent of the power will be dissipated by the ballast.A considerable improvement in efficiency can, however, be achieved by using a resistor with a very pronounced positive temperature characteristic (an ordinary or specially constructed incandescent lamp serves well for this purpose).

A temperature-dependent resistor compensates for variations in the lamp current resulting from variations in the mains voltage, which means

108

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Philips Electromagnetic Lamp manual Types of ballasts, 108, Ignition and re-ignition, Resistor ballasts
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Electromagnetic Lamp specifications

The Philips Electromagnetic Lamp is a transformative lighting solution that enhances both indoor and outdoor spaces. Designed to integrate cutting-edge technology with energy efficiency, this lamp offers a range of features tailored for diverse applications, from residential to commercial use.

One of the primary features of the Philips Electromagnetic Lamp is its powerful electromagnetic technology. This technology allows for efficient energy conversion, resulting in superior light output while consuming minimal electricity. The lamp is engineered to provide a high lumen per watt ratio, making it an environmentally friendly choice for those looking to reduce their carbon footprint without compromising on brightness.

The durability of the Philips Electromagnetic Lamp is another significant characteristic. Built with robust materials, it is designed to withstand various environmental conditions. Whether exposed to heat, moisture, or dust, this lamp guarantees longevity and reliable performance. Additionally, its resistance to temperature fluctuations makes it ideal for a range of settings, including industrial environments where resilience is essential.

In terms of versatility, the Philips Electromagnetic Lamp shines brightly. It is available in multiple wattages and color temperatures, enabling users to select the perfect lighting for different spaces. From warm white shades ideal for cozy home environments to cooler, brighter options suited for workspaces, this lamp adapts to individual needs and preferences.

Moreover, the lamp incorporates advanced light distribution technology. This ensures an even spread of light without dark spots or harsh glares, enhancing visibility and comfort. It is particularly beneficial for large areas needing uniform illumination, such as warehouses, parking lots, and public areas.

Another key feature is its compatibility with smart lighting systems. Many models of the Philips Electromagnetic Lamp can connect to smart home platforms, allowing for remote control, scheduling, and automation. This modern integration enhances user convenience and promotes energy savings by enabling users to optimize their lighting usage according to their routines.

In conclusion, the Philips Electromagnetic Lamp is a perfect blend of efficiency, durability, and advanced technology. Its electromagnetic capabilities, long-lasting construction, diverse options, and smart compatibility make it an outstanding choice for anyone seeking a sustainable lighting solution without compromising on performance.
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