US2497542A

US2497542A - Time delay magnetic starter

Info

Publication number: US2497542A
Application number: US757431A
Authority: US
Inventors: Theodore W Frech
Original assignee: General Electric Co
Current assignee: General Electric Co
Priority date: 1947-06-27
Filing date: 1947-06-27
Publication date: 1950-02-14
Anticipated expiration: 1967-02-14

Description

Feb. 14, 195o T. w. FRECH 2,497,54

TIME DELAY MAGNETIC STARTER Filed June 27, 1947 Inverow Theodore W. Frech,

His 't'ormeg.

Patented Feb. 14,i 1950 TIME DELAY MAGNETIC STARTER Theodore W. Frech, Cleveland, Ohio, assignor to General Electric Company, a corporation of New York Application June 27, 1947, Serial No. 757,431

Claims. l My invention relates to electric discharge devices of the type employing ionizable mediums such as gases or vapors, and more particularly to starting and operating devices and circuits therefore.

Circuits now in Wide use with iluorescent lamps are provided with means for heating the lilamentary electrodes and for impressing a high voltage for a short duration across the electrodes for starting an electrical discharge therebetween.v

l starting occasioned by lingering preheating periods, and varying or erratic operating characteristics with age.

An object of my invention is to provide a new and improved circuit for starting and operating electrical discharge devices employing iilamentary electrodes.

Another object of my invention is to provide a new and improved means for impressing starting voltages across lamentary electrodes of an electric discharge device which after a predetermined inverval of time after the initiation of current iiow through the electrodes impresses starting and operating voltages thereacross.

A further object of my invention is to provide a new and improved starting device for electric discharge devices which embodies a repetitive magnetic switch of the vibratory type accurately controlled by a thermal element.

In accordance with my invention I provide a new and improved starting device and system for iluorescent lamps wherein there is obtained an accurately determined and uniform period of electrode preheating which is reduced to a minimum or optimum value without sacrificing adequate preheating of the electrodes, thereby substantially avoiding the undesirable long Waits in starting the lamps but without imposing severe l operating conditions on the lamps.

` erence may be had to the following description taken in connection with the accompanying drawing and its scope will be pointed out in the appended claims. Fig. 1 is a diagrammatic view of an electric discharge device and a starting and v operating circuit therefore incorporating my invention Fig. 2 illustrates schematically the time delay magnetic starter shown in the circuit of Fig.1. Fig. 3 illustrates a modification of the starting and operating circuit shown in Fig. 1. Figs. 3 and 4 illustrate a commercial embodiment of a starting device embodying certain aspects of my invention.

Referring to Fig. 1, I have there illustrated one embodiment of my invention as applied to an electric discharge device I. The electric discharge device I, such as a fluorescent lamp, therein illustrated comprises an elongated tubular or cylindrical envelope 2 having sealed into the ends thereof

lamentary electrodes

3 and 4, each herein illustrated as comprising a coil, preferably in the form of a coiled coil of tungsten wire activated with oxides of alkaline earth metals, such as a mixture of barium and strontium oxides. The envelope 2 contains an ionizable atmosphere such as a rare gas-like neon, argon or mixtures thereof at a pressure of a few milimeters and a small quantity of mercury which, during the operation of the lamps, has a low pressure of the order of 10 microns. The device I may be a low pressure positive column lamp of the fluorescent type provided with a suitable phosphor or fluorescent coating. This iiuorescent coating upon excitation by the radiation produced by an electric discharge between the electrodes, transforms a shorter wave radiation due to the discharge into longer wave radiation such as radiation within the visible range. For ease of starting, a stripe of strip 5 of conductive material which, for example, may be a metallic paint or graphite mixed with potassium silicate, may be applied to a surface of the envelope. The starting strip 5 may be connected to one or both of the electrodes.

In accordance with my invention the device I is connected across a suitable power supply circuit 6, 6 which for example may be a 115 volt, 60 cycle alternating current source, for supplying current to device I through the usual ballast 1 which serves as a starting inductance. A manual make and break control switch 8 may be used to connect device I to the power supply. A starting and

operating circuit

9, 9 comprising a parallel circuit, including two branches in series with a thermal switch IIJ and

thermionic electrodes

3 and 4 of device I, may include a voltage sensitive means II and a repetitive magnetic switch I2 comprising contact means I3, an armature I4, and a pair of high and low impedance winding means I5 and IB, respectively. The thermal switch I0 comprises a bi-metal strip I1,

i contacts I8 and a heater element I9 and may be,

,for example, a thermal switch such as that dis- 3 closed and claimed in United States Patent No. 2,236,697, granted April 1, 1941, on an application of L. R. Peters and assigned to the assignee of this application. The contact means I3 of the repetitive magnetic switch I2 shunts the voltage sensitive means I I and the high impedance winding means I5, and the contacts I8 of the thermal switch IU shunt the low impedance lwinding means I6. Heater element I9 of the thermal switch I0 is in series relationship to both the

electrodes

3, 4 and the parallel branches of the

starting cir cuit

9, 9. example, may be a glow discharge device having a critical or minimum break-down voltage or it may be a high resistance means. Preferably, such a glow discharge device has a critical breakdown voltage greater than the operating voltage y.

' contains ythe Voltage sensitive-means II in series withl the high and low impedance windings I5 and I6, respectively, ofthe repetitive magnetic switch I2. The other parallel branch of circuit 9,. 9' containsthe contact means I3, anvarma-V ture I 4v ofthe repetitive magnetic switch I2in series With the` contacts IS and the bi-metal strip I1 of. the thermal switch I 0.

When theentire installation is energized by closing switch 8, current flows through the ballast 'I, thermionic electrode 4, voltage sensitive means II, high impedance winding means I 5, low impedance winding means I6, heater-element I9, and iilamentaryelectrode 3. Thehigh impedance winding means I5 and the low impedance.

winding meansl actuate" the armature I4 substantially'instantaneously so; that the normally open contact means I3 engage each other-and short circuit thevoltagesensitive means II and the 4high impedance'winding I5. Contact means.,

I3, however, remain closed by reason ofrthe magnetic attraction of thelowimpedancewndingA I6 for armature I4. Preheating currentfthus continues .to 4now through the ballast 1, electrode 4, contactmeans I3, armatureA I4, low impedance windingv means I6, heater element I9, andelectrode 3 until the heater element I9 actuates the bi-metal strip IIwhich in turn closes the normally open contacts I8 of the thermal switch I0 and shunts the preheating current around the low impedance winding means I6. Upon deenergization oi the low impedance winding means I6, armature I4 is releasedand the current flowing` through the

lamentary electrodes

3 and 4,

andthe ballast or inductance 'I is rapidly re. duced. At thispoint the lamentaryvelectrodes 3 and. 4 are suiciently heated to support an electrical discharge therebetween, and the induced voltagesupplied by the inductance 'I initiates van arc discharge between the electrodes. When `the discharge has vtaken place, the Voltage between the electrodes 3- and 4 drops to'an operating voltage, as for example 60yvolts. The voltage sensitive means so designed thatk its operating,"voltagefis..above. this v.value and tmb-al1 The voltage sensitive means II, forA 4 practical purposes the starting circuit is disconnected from the discharge circuit. The thermal switch IB thereupon cools, its contacts I8 open, and the switch is ready for another cycle of starting operations.

If device I does not ignite at the rst opening of the contact means I3 of the repetitive magnetic switch I2, current again ows through electrode 4, voltage sensitive means II, high impedance winding means I 5, contacts I8, bimetal strip Il, heater element I9, and electrode 3. Contacts I8. at this point are still in engagement with each other because the design of the thermal switch is such that momentary interruptions ofcurrent through its heater element will not open its contacts. Upon the now of currentagain through the high impedance winding means I5, armature I 4 is actuated substantially instantaneously so that the normally open contact means I3 again engage each other and short circuit the Voltage sensitive'means II and the high impedance winding I5. Contact means I3 however, do not remain closed upon this second starting operation because. the low impedance winding means I6 normally used for retaining the contact means I3 in engagement with each other is not energized, butzshort circuited by the thermal contacts I8. Thus, the electromagnet switch operates as a repetitive magnetic switch 'until'the discharge device I ignites.

The ignition or starting devices and circuits may be adjusted to the discharge device I in such a manner that if the device I is faulty or non- `operative the repetitive magnetic switch I2 will ceaseto operate after a predetermined number of starting attempts. This is commonly known as the "lock-out arrangements in the. prior art. Although `the lock-outy arrangement is not Yherein shownor described it may be appledto this circuit;

Fig. 2 incorporates the samercorresponding parts shown in Fig. 1, butv illustrates more in detail thecomponentparts thereof.' A condenser 20 shunts the starting devices of the starting

circuit

9, 9.

Fig. 3 illustrates a modification of the starting circuit shown in Fig. 1 and incorporates the `same vdescribed corresponding 3 parts thereof except the vvoltage sensitivemeans I I .therein illustrated as ,a glow lamp is replaced by a high resistanceelement At I. If desired, instead ofusing a glow lamp ora separate resistance element, the

.` winding means I5 and I6v may bey designed to afford sucient resistance or impedance in themselves for connection in the circuit.l

Figs. 4 and'5 illustrate avcommercial embodiment of my inventionA In accordance with my-invention,y I provide a starting and operating device and Circuit which will after a predetermined interval of time after the initiation of currentv flow through the electrodes impress an operating-voltage -thereacross .Accordingly, I provide av repetitive magnetic switch of the vibratory type accurately, controlled by a thermal element.

Generallyspeaking vI provide a starting device whichv will ignitean electric discharge device one second after the initiation ofl current ow throughtheelectrodes thereof. Asindicated in Figs. 4and 5, I havevtherein illustrated a commercial embodiment of my invention/comprising aninsulatingdisc or member 22;, acore structure --S11Pp,o.1rted;. by: dist- 22` and.; comprising a; rainer vertical magnetic members 23 and a horizontal magnetic member 21! bridging vertical members 23 of the magnetic switch I2, a horizontal rotatable armature I4 supported by a non-magnetic structure 25 mounted on vertical members 23 and supporting at one end thereof the movable portion of contact means I3, stationary contact means I3, and actuating winding means I5 and I6 wound about horizontal member 24. Contact means I3 comprising the stationary contact and the movable contact are actuated by armature I4 and are connected across winding means I5 and glow switch II. Glow discharge device II has a critical breakdown voltage and is designed to establish closure of contact means I3 during an accurately determined interval of time. Contacts I8 of thermal switch I0 are connected across actuating winding means I6 for controlling the time delay between the time of energization of winding means I5 and I6 and the time of initiation of vibratory operation of armature I4. Condenser is supported on member 22 and shunts the

complete starting circuit

9, 9 incorporating my invention.

What I claim as new and desire to secure by Letters Patent of the United States is:

1. In a starting device for electric discharge devices having at least one lamentary electrode, the combination comprising a repetitive magnetic switch comprising normally open contact means, an armature and actuating winding means, said contact means being connected across a portion of said actuating winding means, and a thermal switch comprising normally open contacts connected across a diierent part of said actuating winding means and a heater element located to actuate said contacts to closed position when heated and connected in series with said part of said actuating winding means to establish closure of said contact means during an accurately determined interval of time.

2. In a starting device for an electric discharge device of the type employing a iilamentary electrode, the combination comprising a repetitive magnetic switch of the vibratory type having contact means connected in series relation with said electrode, actuating winding means and an armature for actuating said contact means, a voltage sensitive device connected in series relation with said actuating winding means and having a critical breakdown voltage greater than the normal operating voltage of said discharge device, said contact means being connected across a portion of said winding means and the said voltage sensitive device, and a thermal means comprising contacts connected across a different part of said actuating winding means and a heater element connected in series relation with said part of said actuating winding means for short-circuiting said part of said actuating winding means a predetermined interval of time after the initiation of current ilow through said electrode to cause said magnetic switch to open, said voltage sensitive element eiecting subsequent energizations of the first-mentioned portion of said actuating winding means to cause repetitive closures of said magnetic switch irrespective of the condition of said thermal element when said discharge device fails to conduct initially.

3. In combination, an alternating current supply circuit, an electric discharge device comprising at least one lamentary electrode and employing an ionizable medium, an inductive ballast in series with said device, and a starting device connected across said electric discharge device in series with said lamentary electrode and comprising a repetitive magnetic switch including normally open contact means, an armature and actuating winding means, said contact means being connected across a portion of said winding means, and a thermal switch comprising normally open contacts across a different part of said actuating Winding means and a heater element in series with said part of said actuating winding means to open said contact means at the end of a predetermined interval of time and to produce a transient starting voltage by the change of current through said ballast.

4. In a starting device for electric discharge devices having at least one filamentary electrode, the combination comprising a repetitive magnetic switch comprising normally opencontact means, an armature and actuating winding means, a glow discharge device in series with said actuating winding means and having a critical breakdown voltage greater than the normal operating voltage of said discharge device, said contact means being connected across a part of said actuating winding means and said glow discharge device, and a thermal switch comprising normally open contacts connected across a different part of said actuating winding means and a heater element in series with said magnetic switch and said glow discharge device to establish closure of said contact means during an accurately determined interval of time.

5. In combination with a gaseous electric discharge device comprising at least one lamentary electrode, a main discharge circuit connected to said electrodes, and means for preheating said electrodes comprising a starting circuit connected across said main discharge circuit through said electrodes, means for interrupting said starting circuit and imposing a starting voltage across said discharge device comprising a high resistance means in said starting circuit, a high impedance Winding and a low impedance winding of a magnetic closing means in series with said high resistance means, and a low resistance means of a normally open thermal switch in series with said high resistance means and said high and low impedance windings, contact means actuated by said high and low impedance windings shunting said high resistance means and said high impedance winding, and normally open thermal means shunting said low impedance means.

6. A vibratory magnetic switch comprising an insulating member, a magnetic core structure supported by said member, an armature, actuating winding means and normally open contact means actuated by said armature, said Contact means being connected across at least a part of said winding means, and a thermal switch including a heating element connected in series with said winding means and having normally open contacts actuated to closed position by said heating element upon heating thereof and connected across a different part of said winding means for controlling the time delay between the instant of energization of said winding means and the time of initiation of vibratory operation of said armature.

7. A vibratory magnetic switch comprising an insulating member, a magnetic core structure supported by said member, an armature, actuating winding means and normally open contact means actuated by said armature and connected across a part of said winding means, and a 'fthermalffswitoh .including normally :open v`c onta'cts yneticfcore structure .supported by Vsaid .memloeigA 'an armature, actuating "Winding means andnormally open contact means vactuated by said farma'ture and connected vacross .atleast a part of :said rWinding means, a `glow discharge device connected in series with asaid 'actuating winding meanszand'liaving afcritica'l breakdown voltage to establish lclosure of saidA -eontact means `during `an accurately deter-minable Yinterval tof time, 'and a thermal switch. including normally 'open `contacts 'connected' across a different part `of said windingmeans for controlling the time delay :betweenthe instant of energization 'of y'said Winding vn'leans and the 'time 'of initiation o'f vbratory :operation of said armature.

S9. A starter comprising the combination of a rmagn'etic relay 'including a vhigh Limpedance lactuating winding and alow impedance 'holding winding, an Iarmature 'and fa pair of normally open Acontacts :actuated by 'said armature 'and conneo'ted'in multiple yWith Ithe 4high "impedance Winding and in series with the low impedance winding, 'anda thermal switch including a heater element connected in series with the relay windings and having normally lopen contacts actuated by said heater `element :and connected sinrmultiple. with :the .said low :impedance Winding;

'.11'0. .A starter comprising .the :combination .fof a voltage sensitive device, ia :magnetic relay 'clllding respectively high 'and Flow impedance 'ac-f tuatin'g .andfholdingxwindings in series with 'said voltage sensitive device, 4'anda pair of normally l'open fconta'ots :actuated by rsaid armature 'and connected in multiple with both the .high im :pedance Winding :and the said voltage Vsensitime device, and a thernralswitch including :a Cheater element .connected .in :series with the 'relay Wi-nd,- ings and :the voltage :sensitive device `and Ahay-ing enormailly Vopen contactsfactua-ted 'by said heater Velement and 'connectedin multiple Witl'i the Ysaid lewimpedance winding.

'THEODORE W.

YREFEREN CES CITED y T-he following references are 'of record in the lfile 'di this -patent:

UNITED .STATES vPATENTS Number