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5
E L E C T RO M AG N E T I C L A M P
C O N T RO L G E A R
BALLASTS
5 1
1 1
Main ballast functions
In chapter 2.1 of this Guide: General aspects, section 2.1: Main ballast
functions, the main functions of ballasts have been described.The term
'ballasts' is generally reserved for current limiting devices, including
resistors, choke coils and (autoleak) transformers. Other pieces of
auxiliary equipment are compensating capacitors, filter coils and
starters or ignitors. Some systems use an additional series capacitor
for stabilisation.
With the components summed up, all control functions which are
necessary to operate standard fluorescent lamps can be carried out.
Special arrangements, including sequence start, constant wattage or
dimming circuits will not be described in this Guide, as such circuits
are more and more being replaced by the modern high-frequency
(HF)systems.
1 2
Stabilisation
In section 3.2: Stabilisation, the need for current stabilisation in
fluorescent lamps has been described, resulting in the following two
formulae:
and:
where
From these formulae it can be concluded that the power of the lamp
(and therefore the light output) is influenced by:
- the lamp voltage V
the operating temperature (see section 5.3.12:Ambient and operating
temperatures) and on the lamp current, according to the negative
lamp characteristic (see section 3.2: Stabilisation).
- the lamp current I
section 5.3.13: Effects of mains voltage fluctuations), the lamp voltage
and the linearity of the ballast impedance.
In order to avoid undesirable variations in light output as a consequence
of mains voltage fluctuations, the lamp voltage must be not more
than approx. half the value of the mains voltage (100 to 130 V) and the
impedance should be as linear as possible.
1 3
Ignition and re-ignition
In chapter 3: Lamps, section 3.3: Ignition, the need for ignition of a
fluorescent lamp has been described.
107
/
I
= (V
- V
)
Z
lamp
mains
lamp
ballast
P
= V
. I
.
lamp
lamp
lamp
lamp
I
= the current through the lamp
lamp
V
= the mains voltage
mains
V
= the voltage across the lamp
lamp
Z
= the impedance of the ballast
ballast
P
= the power of the lamp
lamp
= a constant called lamp factor
lamp
, which in turn is highly dependent on
lamp
, which is dependent on the mains voltage (see
lamp
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Summary of Contents for Philips Electromagnetic Lamp
- Page 1 E L E C T RO M AG N E T I C L A M P C O N T RO L G E A R BALLASTS Main ballast functions In chapter 2.1 of this Guide: General aspects, section 2.1: Main ballast functions, the main functions of ballasts have been described.The term ‘ballasts’...
- Page 2 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.
- Page 3 The right ballast for a given lamp and supply voltage should be chosen by consulting documentation and/or ballast markings. The Philips standard range of ballasts is for supply voltages of 220/230/240 V and for frequencies of 50/60 Hz. ‘TL’ R...
- Page 4 1.4 Types of ballasts The most important value for stabilisation is the ballast impedance. It is expressed as voltage/current ratio in ohm (Ω) and defined for a certain mains voltage, mains frequency and calibration current (normally the nominal lamp current). Chokes can be used for virtually all discharge lamps, provided that one condition is fulfilled: the mains voltage should be about twice the arc voltage of the lamp.
- Page 5 This information suffices to find the right ballast for a certain application.Additional information can be obtained on request or can be found in special application notes. Philips ballasts are designed for use with IEC standardised fluorescent lamps. and ∆T...
- Page 6 1.6 Maximum coil temperature t Another value marked on the ballast is the coil temperature rise ∆t. This is the difference between the absolute coil temperature and the ambient temperature in standard conditions and is measured by a method specified in IEC Publ. 920 (EN 60920). Common values for ∆t are from 50 to 70 degrees in steps of 5 degrees.
- Page 7 1.7 Watt losses As in some applications the power consumption is of prime importance, there are low-loss ballasts for the major lamp types ‘TL’D 18, 36 and 58 W ( BTA**L31LW).The 18 and 36 W LW ballasts are bigger than the standard types, resulting in lower ballast temperatures and 25 to 30 per cent less ballast watt losses.
- Page 8 Fig. 106. Working principle of a glow- discharge starter circuit. 1. The heat from the discharge in the starter bulb causes the bimetallic electrodes to bend together. 2. When the bimetallic electrodes make contact, a current starts to flow through the circuit, sufficient for preheating the electrodes of the fluorescent lamp.
- Page 9 In the Philips programme there are two types of electronic starters: one in the canister of the glow-switch starters (two-pin types S2-E and S10-E Perform version), and one in a plastic housing (four-pin type ES08).
- Page 10 3.1 Components Information about lamps can be found in the lamp documentation, where also the type of lampholder or lamp cap is mentioned. Be sure to use the appropriate lampholder, as there are many different types. Lamp types with different wattage are in principle not interchangeable in a certain circuit, even though they may have the same lamp cap and do fit in the same lampholder.
- Page 11 3.2 Capacitors To do things well, some aspects have to be considered: - First of all, capacitors for discharge lamp circuits have to fulfil the requirements as specified in IEC publications 1048 and 1049.The use of PCB (chlorinated biphenyl) is forbidden. - It is recommended that capacitors which have some approval marks, such as VDE, KEMA, DEMKO or ENEC be used.
- Page 12 Fig. 108. Impedance of a filter coil, a capacitor and a coil/capacitor combination as a function of frequency. 3.2 Capacitors Capacitors for lighting applications must have a discharge resistor connected across the terminals to ensure that the capacitor voltage is less than 50 V within 1 minute after switching off the mains power.
- Page 13 Fig. 109. Different ways of grouping capacitors to match them with the corresponding filter coil. Fig. 110. Power factor correction with a parallel compensating capacitor. 3.3 Filter coils There are other advantages to be gained from employing filter coils. The parallel capacitor can cause troublesome switching phenomena to occur, which can give rise to very large current surges.Although these surges are of only very short duration (a few milliseconds), they are nevertheless sufficient to cause switching relays to stick or circuit...
- Page 14 Fig. 111. Lamp current (I ), lamp voltage (V and mains voltage (V Fig. 112. Example of a vector diagram showing lamp voltage and lamp current in phase. Fig. 113. Uncompensated circuit with lamp current and mains voltage out of phase. 3.4 Power factor correction This can be seen in Fig.
- Page 15 3.4 Power factor correction ballast, the capacitor current is leading 90 electrical degrees to the capacitor voltage (which is the mains voltage). So the capacitor current has the opposite direction of I (see Fig. 114). I l cos Fig. 114. Compensated circuit. Maximum compensation is achieved when the current through the capacitor I ;...
- Page 16 Fig. 115. Duo-circuit with the capacitor placed in series with one of the ballasts. 3.4 Power factor correction The series capacitor has an impedance which is twice the normal ballast impedance, resulting in a power factor of approx. 0.5 capacitive for one branch.Together with the power factor of 0.5 inductive for the other branch, the total power factor of the two branches is approx.
- Page 17 Fig. 116. Voltage/current characteristic of an inductive ballast (example). Fig. 117. Tandem circuit with two lamps in series on a common ballast. 3.4 Power factor correction Mains voltage 90 % 100 % Circuit Ind. Cap. Ind. Z ballast (Ω) Z capacitor (Ω) Z result (Ω) Therefore the behaviour of the inductive and capacitive branch of a duo-circuit is different at mains voltage deviations and deviations of the...
- Page 18 3.5 Series connection of lamps Parallel connection of two lamps on a common ballast is impossible because of the negative characteristic of the fluorescent lamp.All the current would flow through the lamp with the lower arc voltage. Moreover, once the first lamp is ignited the lamp voltage is too low for the ignitor of the second lamp to ignite this lamp.
- Page 19 Fig. 119. The consequences of interrupted neutral in a phase/neutral network. Fig. 120. Resonance in a delta-network. 3.6 Neutral interruption and resonance total 230V 1000 400V 230V This makes 1000 + 250 = 1250 Ω. So the current will be 400 / 1250 = 0.32 A.
- Page 20 Fig. 121. Resonance in a star-network. 1) One lamp, inductive or compensated with electronic or glow-switch starter ‘TL’, ‘TL’D, ‘TL’E, ‘TL’U, PL-L, PL-T, PL-T(S)(C) 4-pins 2) Two lamps, inductive or compensated with electronic or glow-switch starter ‘TL’, ‘TL’D, PL-L 3) One lamp, inductive or compensated without starter PL-S, PL-C, PL-T (starter incorporated) 3.6 Neutral interruption and resonance...
- Page 21 4) Two lamps, inductive or compensated PL-S, PL-C (starter incorporated) 5) One or two lamps, inductive, capacitive or compensated with electronic starter ES08; ‘TL’, ‘TL’D The capacitor C* must be of the X2 type 100 nF/250 V 6) Duo-circuit, two lamps, with electronic or glow-switch starter 7) Duo-circuit, four lamps, with electronic or glow-switch starter...
- Page 22 3.8 Mains voltage interruptions and short-circuiting Mains voltage interruptions and short-circuiting For various reasons, the supply voltage can be subject to deviations; therefore a certain degree of deviation from the rated value has been taken into account everywhere.With gas-discharge lamps deviations of up to +/- 10 per cent of the rated supply voltage normally have no detrimental effects.
- Page 23 Fig. 123. Lamp voltage wave form constructed by the odd harmonics from one to nine, according to the formula: f(t) = 4U/π (sin t + 1/3sin3 t + 1/5sin5 t + ...). Fig. 124. Hysteresis cur ve of a typical copper-iron ballast.
- Page 24 4 % ninth harmonic: All Philips inductive compensated lighting circuits (P.F. = 0.5) comply with this standard.The capacitive branch of a duo-circuit has higher values, but as a whole the duo-circuit meets this standard. To obtain a good power factor (0.9) of the system with gas-discharge lamps, mostly parallel capacitors are used.
- Page 25 Fig. 125. Fundamental and third harmonic in a three-phase mains. R, S and T are the fundamentals in the three conductors. Owing to the phase shift, this results in a zero current in the neutral lead. a) Third harmonic of a phase, b) Third harmonic of all three phases in the neutral lead.
- Page 26 3.10 Electromagnetic interference Fig. 126 shows an example of a delta filter used for suppressing radio interference.The apex of the filter must be connected to the ground. More complicated filters are used in three-phase networks. Avoid earth looping (all earth terminals to one point) and create maximum distance between audio and lighting cabling.
- Page 27 3 12 Fig. 127a. Relative values of luminous flux ( ), lamp voltage (V ), lamp current (I ) and lamp wattage (P ) as a function of lamp head temperature, for a PL lamp. Fig. 127b. Relative values of luminous flux ( ) as a function of the ambient temperature and the burning position (PL lamp).
- Page 28 Fig. 128. The maximum recommended ambient temperature at which an SL lamp can operate is 55 ºC. The part of the lamp with the highest temperature is a 5 mm wide section around the circumference of the housing. The temperature measured in this region, on the surface of the housing, is about 150 ºC.
- Page 29 3.12 Ambient and operating temperatures 2) Gear a) Ballasts The main ballast temperature parameters t (maximum permissible coil temperature) and ∆t (coil temperature rise in standard test) are described in section 5.1.6. Ballasts are normally mounted directly inside a luminaire.The actual ballast coil temperature in practice depends on the cooling properties of the ballast surroundings, e.g.
- Page 30 Fig. 129. Influence of temperature increase on lamp current (I), lamp voltage (V), lamp power (P) and luminous flux ( ) for a 40 W fluorescent lamp on inductive and capacitive ballasts. 3 13 3.12 Ambient and operating temperatures In outdoor applications a natural air circulation around the luminaire is assumed, which gives a cooling effect of about 10 ºC.The same luminaire with an indoor ambient temperature limit of 25 ºC, will in practice have an outdoor ambient temperature limit of 35 ºC.
- Page 31 Fig. 130. Influence of variation of the supply voltage on a PL-L 18 or 24 W lamp operated in a lagging (inductive) circuit (Fig. 130a) and in a leading (capacitive) circuit (Fig. 130b). Relative values of luminous flux ( ), lamp current (I ), lamp wattage (P ) and lamp...
- Page 32 3.14 Electrical wiring Fig. 132. Solid-core wire inside a luminaire for fluorescent lamps. White wires are used where the wiring is visible from below. The diameter (or rather the cross-sectional area) of the wire must be matched to the strength of the current flowing through it.A wire whose area is too small has a resistance that is too high and it will become warm, the resulting heat loss reducing the efficiency of the luminaire.
- Page 33 3.14 Electrical wiring protection can be obtained by covering the insulation with a glass-fibre sleeve. In order to keep the chances of heat damage to the insulation to a minimum, the wiring run is so chosen as to avoid as far as possible any ‘hot spots’...
- Page 34 3.16 Dimming 3 16 Dimming Dimming can be defined as the reduction of the luminous flux of a lamp, either continuously or in steps, by reducing the operating current.This is not always possible without adversely affecting the performance of the lamp. Basically, dimming is achieved in one of the following ways (see Fig.
- Page 35 ‘top dimming’). For indoor installations, however, top dimming is of limited practical use and at ambient temperatures below 5 ºC krypton- filled lamps, like the Philips ‘TL’D may become unstable when dimmed. The disadvantage of thyristor dimming where lamp circuits incorporating glow-discharge starters are concerned, is that the dimmed lamp will cause the starter to become conductive.At what degree of...
- Page 36 3 17 Fig. 136. Prevention of the stroboscopic effect by using combined inductive and capacitive circuits (‘lead-lag’ or duo-circuit) and by spreading the lighting over the three phases of the supply. 3.17 Stroboscopic effect and striations Stroboscopic effect and striations For this subject, see also section Lamps, 3.10.
- Page 37 Fig. 137. Colour shift during the 100 Hz light ripple of a fluorescent lamp 3.17 Stroboscopic effect and striations 2.The light ripple can also have an effect on the quality of camera pictures.This phenomenon may become apparent when CCD colour cameras operate in auto-shutter mode and the lighting of the area is predominantly with fluorescent lamps, The auto-shutter mode is normally selected when cameras are...
- Page 38 Fig. 138. The 20 msec frame integration time of a CCD colour camera with the automatic shutter switched off, compared with the 100 Hz fluorescent light ripple. Fig. 139. Using the automatic shutter and with the camera locked to mains frequency, it is possible to shoot stable and white pictures.
- Page 39 3.17 Stroboscopic effect and striations depends on several factors, including lamp position, supply voltage, temperature, age of the lamp (electrode) and also of the lamp current wave form (peak factor). 4. Striations are noticeable as a pattern of more or less bright regions in the long discharge tube of fluorescent lamps.The pattern can move through the discharge tube.
- Page 40 switching time (s) Fig. 140. Switching characteristics of various types of main circuit breakers. According to CEE-19-2 3.18 Circuit breakers, fusing and earth leakage The same applies to main circuit breakers (MCB’s).Although the switching characteristics of MCB types are laid down in recommendations like CEE-19-2 of different types and brands can differ considerably.
- Page 41 3.18 Circuit breakers, fusing and earth leakage Information on what lighting load a certain MCB can handle may be given by the MCB supplier, provided information about the cabling lay-out, lamp type and circuit is available.As a guide, a practical value for the figure (1) of the 10 A MCB type C represents 1500 W lighting load with the conventional gear.
- Page 42 There are two different official earth classifications: 1) Protective earth (PE) with symbol 2) Functional earth with symbol With electromagnetic lamp control gear we only have to deal with protective earthing, which is permissible by mounting the gear to an earthed metal component.
- Page 43 3.18 Circuit breakers, fusing and earth leakage Earth leakage currents in lighting circuits depend on the quality of all system components and on the circumstances (humidity, dust, age). With respect to luminaires, IEC 598 restricts these currents to 0.5 or 1 mA, depending on the insulation classification.The earth connection may consist of an earth lead or the capacitance between the luminaire and its surroundings.
- Page 44 3.19 Fault finding - tube blackening, - lamp type and wattage must correspond to that required by ballast label, - lamp orientation designation incorrect for application (base up, base down). 1B:Visual inspection of components - damaged ballast, starter or capacitor, - evidence of moisture or excessive heat, - loose, disconnected, pinched or frayed leads, - incorrect wiring,...
- Page 45 3.19 Fault finding Fault IV: lamp flickers. • Possible cause: - lamp operating voltage too high, end of lamp life, - low supply voltage, check ballast connection, - burning position out of specification. Fault V: strong blackening of lamp, light output reduction. •...
- Page 46 3.19 Fault finding If the mains current is about half the lamp current, the capacitor is in order, resulting in a power factor of approx. 0.9. 2) Disconnect capacitor from circuit and discharge by short-circuiting terminals. Check capacitor with ohmmeter set at highest resistance scale. If the meter indicates a very low resistance which then gradually increases, the capacitor is in order.
- Page 47 3.19 Fault finding For safety and good ignition, earthing of the luminaires and the electrical system can be essential. Check the system’s current to real earth (see section 5.3.18: Earth leakage).The voltage between real earth and the neutral conductor is not limited by safety regulations, but lies normally between 0 and 6 V.
- Page 48 Philips range, information can be obtained from the local Philips organisation. - Starters are related to lamp type, ballast and supply voltage.The Philips range of starters cannot be used for other voltages than those for which they are specified.All starters are suited for 50 and 60 Hz.