h'eactors are used in discharge lamps such as 'e.g. fluorescent tubes, in which the reactors limit the lamp current through their inductive resistance.

'i'l.e present invention relates to a reactor for the above mentioned . purpose, said reactor comprising a core provided with a coil. The coi ^** -.- is made up of yokes and legs in such a manner that at least two openings are formed in the core. The yokes and the legs of the core are made up of laminations of plates. One air gap is arranged between one of the legs and a yoke.

0 I'. actors (reactive coils) of this kind are previously known per se . ^■ '.') & i-o are tv/o important factors that have to be borne -in mind when designing reactors for fluorescent 'tubes. The reactor must be inexpensive to muf.acture and it must have a good operating economy, which means that its loss of power should be as small as possible. In the normally us-.-il reactors for './ fluorescent tubes the loss of power amounts to about ^•) -.2 ' .

' rι order to optimize the above mentioned factors it is essential to bring about that the total length of iron in the reactor is as short as po*_f_ille and that the necessary plates for making up the iron core are cut wit!, "m

' ^~ 0 little waste as possible. To this end it should be seen to that the jt.tr'.- ing material is used in the best way. It should furthermore be seen Lo that the space for taki g up the coil has proper dimensions in relation Lo the iron cross section, so that the amount cf copper in the coil and iron in the i-ore results in the best possible optimal effect. It should i _" ^* . "i υbE'i vfc.l that the area of the iron is inversely proportional to the numbe oi ^" urna of winding of lie copper thread.

A further c ^t or that influences the design of a reactor for fluoreaceu ' iub-.s i_- tυ αec- to that gaps in the construction do not create a leak ^" ' _' > flux. Such a leak flux might excite adjacent iron parts and put thos-.- paj-tc i ^' o vibrations, which would cause a non-desirable noise.

up of laminations of plates of ferro-magnetic material having a magne preference direction. This entails an essentially improved flux densi by what means the utilization factor of the reactor is improved.

One kind of a low-losa reactor has been suggested, which comprises a 5 made up of standardized elements, that are cut from bands of rolled, directionally oriented plates (fig. 1 ) . This reactor comprises two co and the air. ap is divided into four gaps. In this way the leak flux minimised and a low level of noise is obtained. Such a reactor entail low loss of power, but the relatively large area of copper makes it 10 expensive to manufacture, due to the high costs of copper. In order t reduce the cost of material it has therefore been suggested to make a reactor with a reduced copper area and an increased iron area (fig. 2)

V! ιι - r.ii i'r.- u l ^' I h i :! r '< ^■ .• ^{■ ■} ."; I. o r i n :ιl :J n a *' u p f" ti I .'u iib i.l'il 1 y. titi 'ι~_ OIII'J I I ϋ l o l ^'

. ^' irt.'cti nally oriented plates. There ia no waste wh n cutting the l.a I'. : ^* inOe kti'. ;ιVc *_tli ^* al; ah ang ^' Lrf V A 'ι i rc ^' jatiOπ to tlm rolling -1 I ^** for the plates. This reactor entails a low los_s ^' of power but. its comp is so complicated that the manufacture of it, becomes too ' x ensi e .

! ti the reactor according to the present invention at least one of the yokes is made up of laminations of plates of a non-dirεctionally orie 20 kind, whereas the remaining yoke and legs in the core consist of lami tions of plates having a magnetic preference direction. The core of o embodiment of the invention comprises an upper and a lower yoke havin intermediary legs wherein the two yokes are made up of laminations of uon-directionally oriented plates.

_ ^** _■ " ie preferred embodiment of the invention is described further in del below and with reference to the appended drawings wherein:

figs. 1-2 show examples of reactors having directionally oriented plat

fig. 5 shows - partly in section - a perspective view of a prefer reactor,

; ^' fig. A shows a schematic cross section of the preferred reactor.

Λ-j has already been mentioned above, there are known reactors (figs. ¹ having -Ox-c∑: made up of directionally oriented plates. The embodiment

according to fig. 1 comprises two coils b and four air gaps c. Λ reactor having the coil enclosed by directionally oriented plates a with air gaps c according to fig. 2 entails a reduced copper area and an increased iron area.

The reactor 1 according to the invention (figs. 3-4) comprises an iron core, which is composed of an upper yoke 2 and a lower yoke 3 having three' intermediary leg3 4 ^a _> 4b,4c. The coil 5 of the reactor 1 is carried by the middle leg 4b. The air gap > is aituated between the upper yoke 2 and said middle leg 4b. Each of the yokes 2,3 and the legs is made up of 10 laminations of plates. The laminations in the leg3 4a,4b, c consist of plates of f rro-magnetic material having a magnetic preference direction. The yokes and the legs are connected in a not described mariner to a closed unit 1.

In I e ,'tiι ^a)* c- -πcctl)(_ ⁽ l LIit- ]αs3 of IIPV-.-' ^* in Lh'_ <-i _' kral.ing 1 '. condition is about 4•5 W. In comparison with the normal loss of powt_r υf 0-12 -I this new reactor results in a 50?ό reduction of the loss of power. Tn view of the fact that every single fluorescent tube is equipped with α reactor, the save of energy is quite considerable.

The following is an example showing the loss of power in a low-loss c- -.r-.n tor 20 according to fig. 4• It is assumed that: the iron area A ■* ^• *** 2 x 6 = 12 cm the flux = 13700 Gauss at .f_8 V the frequency f = ^' 50 Hz tiie diameter of the thread = 0.40 mm

_", "'lie turns of winding of the coil can now be calculated from the form-ila: t - ^~ i χ \ - ^Veff ' ^ ' ° ^S • N - ^• V _ _ j _{= 46} > ^{■' x Λ} - U . 2 7T£ ' ^{W _} A ^{~ ~} 2_ ^{~ D}

!i = 4t-5 turns

2 The area of the coτ.>per thread = 0.4 x 0.] x A'-> ^r = 74-4 mm ^" .

Under the assumption that the filling factor is 0.7, the space of the

^~~ a.' ^-1 Δ 2

.0 ι .-ι_ad = ' j.'' ^* ?, = 10t. r__r: (total coil space).

. ,'

.!.(. ^• length of the- coil = -~- & 20 mm

The resistance of the coil can now be calculated:

R = 4 x 2 (0.02 + 0.06 + 0.01) x 0.142 = 12X1

15°

The corresponding loss of power at a current intensity of 0.44 is the

P. _r o = 12 x 0. ² = 2.22 V.

5 The resistance and loss of power at 90 C is also calculated below:

^R 90° 12 + 12 x 0.004 x 75 15.6-fL

90' = 1 5 .6 x 0 .43 = 2.89 W

The copper weight = 465 x 2 (0.02 -. 0.Cc + 0.01 ) x = 0.008 kg .he copper cost = 0.088 x 16.32 = 1.44 Sw. crowns.

U The laminations in the legs _|a,4c have the dimensions 20 x 10 mm.

The laminations in the middle leg 4 have the dimensions 19 x 10 mm.

The laminations in the yokes 2,3 have the dimensions 0 x 10. mm.

Vol ume of non-oriented iron = 1 0 50 2 60 - 4 ( — ^ — ^** ) x -^ =

= 55.680 mm- ⁵ 5 The weight of non-oriented iron = O.O56 x 7- = 0.4 k

Volume of oriented iron = 10 x 20 x 60 x 2 + 20 x 1 x &0 = 6.800 mm The weight of oriented iron = 0.04-^8 x 7-4 = 0-35 kg

_r Total weiglit of iron = 0. 1 + .35 = 0.7* ^' kg Total loss of power in iron = 0.41 x 2.2 + 0.35 x 0.8 = 1.18 V/ 0 The iron cu_t = 0.41 x 2.05 + 0.3 x 6.02 = 2.95 Sw. crowns 'i'υtal copper and iron cost = 1.44 + 2. 5 = 4.39 Sw. crowns. Total loss of power in copper and iron = 2.89 + 1.18 = 4.07 W.

These calculations thus verify the above mentioned loss of power in -_. reactor according to the invention. The calculations also show that t 5 coot of a reactor according to the invention Is :.ot higher than that an ordinary one.