GB2170669A - Solenoid energisation circuit - Google Patents
Solenoid energisation circuit Download PDFInfo
- Publication number
- GB2170669A GB2170669A GB08602481A GB8602481A GB2170669A GB 2170669 A GB2170669 A GB 2170669A GB 08602481 A GB08602481 A GB 08602481A GB 8602481 A GB8602481 A GB 8602481A GB 2170669 A GB2170669 A GB 2170669A
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- GB
- United Kingdom
- Prior art keywords
- coil
- circuit
- ofthe
- current
- power supply
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
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Classifications
-
- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03K—PULSE TECHNIQUE
- H03K17/00—Electronic switching or gating, i.e. not by contact-making and –breaking
- H03K17/51—Electronic switching or gating, i.e. not by contact-making and –breaking characterised by the components used
- H03K17/56—Electronic switching or gating, i.e. not by contact-making and –breaking characterised by the components used by the use, as active elements, of semiconductor devices
- H03K17/60—Electronic switching or gating, i.e. not by contact-making and –breaking characterised by the components used by the use, as active elements, of semiconductor devices the devices being bipolar transistors
- H03K17/64—Electronic switching or gating, i.e. not by contact-making and –breaking characterised by the components used by the use, as active elements, of semiconductor devices the devices being bipolar transistors having inductive loads
-
- H—ELECTRICITY
- H03—ELECTRONIC CIRCUITRY
- H03K—PULSE TECHNIQUE
- H03K17/00—Electronic switching or gating, i.e. not by contact-making and –breaking
- H03K17/51—Electronic switching or gating, i.e. not by contact-making and –breaking characterised by the components used
- H03K17/56—Electronic switching or gating, i.e. not by contact-making and –breaking characterised by the components used by the use, as active elements, of semiconductor devices
- H03K17/72—Electronic switching or gating, i.e. not by contact-making and –breaking characterised by the components used by the use, as active elements, of semiconductor devices having more than two PN junctions; having more than three electrodes; having more than one electrode connected to the same conductivity region
- H03K17/73—Electronic switching or gating, i.e. not by contact-making and –breaking characterised by the components used by the use, as active elements, of semiconductor devices having more than two PN junctions; having more than three electrodes; having more than one electrode connected to the same conductivity region for dc voltages or currents
- H03K17/731—Electronic switching or gating, i.e. not by contact-making and –breaking characterised by the components used by the use, as active elements, of semiconductor devices having more than two PN junctions; having more than three electrodes; having more than one electrode connected to the same conductivity region for dc voltages or currents with inductive load
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- Electronic Switches (AREA)
Abstract
A solenoid coil 1 is supplied with a high initial current followed by a lower holding current, using a switching device controlled by the charging of a capacitor. On switch-on, thyristor 7 is supplied with gating pulses to turn it on early in each half-cycle of the input AC waveform: as the capacitor 11 charges, the firing angle is progressively delayed in successive cycles, reducing the current, until the thyristor fails to fire, when holding current is supplied via a shunt path 10, 14. Current limiting means (figs 3, 4) may limit the initial current magnitude. An alternative arrangement (figs 5, 6) uses transistors, and multiple solenoid windings, arranged in parallel for initial energisation and series for subsequent holding current. <IMAGE>
Description
SPECIFICATION
Solenoid energisation circuit
This invention relatestoacircuitforenergisingthe solenoid of a mechanism, such as a contactor our a relay, in which an armature is pulled-in by operation of the solenoid.
Solenoid-operted mechanisms may be oftwo types, namely those energised by alternating current and those energised by direct current.
In an alternating current solenoid a laminated core must be used, in order to reduce the loss due to the eddy currents which are induced in the core by the alternating magnetic field. A shading coil is provided to create a phase-shifted field to maintain the solenoid in the pulled-in state during reversal of the alternating field, thereby preventing chattering ofthe armature.
When the solenoid is de-energised, so that there is a relatively large gap between the armature and the poie piece, the inductive reactance of the solenoid will be low. Hence, when the a.c. supply is switched on, the energising current will be large, and this initial large current inrush provides the necessary pull-in force.
Pulling-in of the armature reduces or closes the air gap, and the inductive reactance ofthe solenoid increases, so that the hold-in current is considerably lessthanthepull-in current.
The value of the hold-in current and the magnitude ofthe eddy current losses determine the amount of heat which has to be dissipated, and hence the size of the winding and the mechanical parts of the solenoid device.
In a directcurrentsolenoid, a core of solid magnetic material may be used, because no eddy current losses are involved. The inductance of the coil is not significant, and the coil current is substantially constant, being determined by the d.c. resistance of the coil. The coil ampere-turns are therefore constant, and a steady magnetic field is produced. The resulting pull-in force has to be large enough to pull the armature up to the pole piece. Once the armature is pulled in, the force required to hold it in is very much less, so the energising current can be substantially reduced. An economy resistance is therefore commonly inserted in series with the coil when the armature is pulled in, in orderto reduce the current and so prevent overheating ofthe coil.
To summarise, the a.c. type of solenoid device therefore provides automatic reduction of the energis ing currentwhenthe armature has pulled in, but requires a complicated structure involving a laminated core and a shading coil. The d.c. type of solenoid has a very much simpler structure, but requires some meansfor reducing the energising currentwhenthe armature has pulled in.
It is an object of the present invention to provide a simple circuit which will energise a d.c.-type solenoid device, without the need for an economy resistor.
According to the invention there is provided a solenoid drive circuitfor energising the coil of a solenoid device from a power supply, the circuit comprising switching means to cause a relatively high currentto pass through the coil from the power supply in a pull-in mode and a relatively lowcurrentin a hold-in mode; and a timing circuit including first capacitance means which receives charging current from the power supply, the switching means being operableto switch from the pull-in mode to the hold-in mode when the charge on the first capacitance means reaches a predetermined level.
Embodiments of the invention will now be described, by way of example, with reference to the accompanying drawings, in which
Figure lisa circuit diagram of a halfwave a.c.
energisation circuit for a d.c. solenoid device according to a first embodiment ofthe invention;
Figure 2 is a circuit diagram of a full-wave a.c.
energisation circuit according to a second embodiment; Figure3 isa circuitdiagram of athirda.c.
embodiment;
Figure 4 is a circuit diagram of a fourth a.c.
embodiment;
Figure 5 is a circuit diagram of a first embodiment of a circuit for energising a d.c. solenoid device from a d.c. supply; and
Figure6 is a circuit diagram of a modification ofthe circuit of Figure 5.
Referring to Figure 1 ofthe drawings, the coil 1 of a d.c.-type solenoid is energised from an a.c. supply 2 by means of an energising circuit 3. An input point4 of the circuit 3 is connected to the lineterminal of the supply via a switch 6. The circuit 3 comprises a thyristor7, the anode of which is connected to the point4 and the cathode of which is connected to one end 8 ofthe coil 1. The other end ofthe coil is connected to the neutral terminal 9 ofthe supply. A gating circuitforthethyristor7 comprises a diode 10, a capacitor 11 and a resistor 12 connected in series between the points 4 and 8. The junction 13 between the capacitor 11 and the resistor 12 is connected to the gate electrode of the thyristor7. A resistor 14 is connected between the point 8 and the junction 15 of the diode 10 and the capacitor 11.A capacitor 16 is connected between the points 4 and 8, and a freewheel diode 17 is connected across the solenoid coil 1.
In operation of the circuit, when the switch 6 is first closed, a current charging the capacitor 11 flows through the diode 10, the resistor 12 and the coil 1 during the positive half cycle. The voltage across the
resistor 12 triggers the thyristor7 near the beginning
of the half cycle, and full forward current is passed through the coil for the remainder of the half cycle.ln the subsequent negative half cycle, current flow through thethyristor and the gating circuit is blocked, butfreewheel currentflowsthrough the coil 1 and the
diode 17. The charge on the capacitor 11 is largely
retained during the negative half cycle, leaking away
only slowly through the resistor 14.The next positive half cycle ofthe supply charges the capacitor 11 further, and the thyristor7 is again gated on and
passes full forward currentthroughthe coil. This is
repeated for a succession of supply cycles, and the
The drawing(s) originally filed was (were) informal and the print here reproduced is taken from a later
filed formal copy.
solenoid is pulled in. During each successive positive
half cycle the capacitor 11 is charged further, the charging currenttherefore gradually decreasing.The charging currentwill be, effectively, the ripple current caused bythe capacitor 11 discharging through the resistor 14 and recharging to the peakvoltage level. A state will be reached in which the charging current is so small that the voltage produced across the resistor 12 is insufficentto fire the thyristor 7.
Thereafterthe thyristor7 remains switched off, and the currentthrough the coil 1 therefore reduces to a hold-in level determined bythevalues ofthe resistors 12 and 14,the resistance ofthe coil 1, the small recharging current ofthe capacitor 11 and the value of the capacitance 16through which a small current component flows in each half cycle. This relatively small hold-in current continues to flow until the switch 6 is opened. The capacitor 11 then discharges through the resistors 14 and 12,so thatthe circuit is again readyfor high-current operation when the switch is reclosed. The values ofthe components 11, 12 and 14 determine the resettime required beforetheswitch is reclosed.
The values of the resistors 12 and 14andthevalue of the capacitor 11 also determine the number of positive half cycles available for pulling-in the solenoid before the thyristor7 fails to fire. It is of no great importance, within reasonable limits, how tong the thyristor continuestofireafterthe solenoid has pulled-in.There is therefore, a considerable tolerance on those values.
However, the values of the resistors 12 and 14 must be chosen such thatthe application of a mains supply of highervoltage or higherfrequencythan normal will not cause the circuitto firethethyristor7 continuous
ly. The time constant ofthe gating circuit should be short enough to allow rapid resetting ofthe circuit, so that reclosing ofthe solenoid device can be effected soon after the switch 6 has been opened. The resistor 12 may be split into two resistors in series, with the gate ofthe thyristor 7 connected to the junction of those resistors instead ofthe junction 15. The combined values ofthose resistors will then determine the charging rate ofthe capacitor 11, butthe ratio oftheir values will determine the sensitivity of the thyristor.
Figure 2 shows a modification ofthe circuit of Figure 1 to enable some bi-directionalflowofthesolenoid hold-in current. The circuit is similarto that of Figure 1, exceptthatthefreewheel diode 17 is, in effect, replaced by a diode bridge comprising diodes 20-23.
In this circuit, in the positive cycle, hold-in current flows from the terminal 5, through the capacitor 16 (added to which is a small charging current compo nentthroughthe resistor 12), through the diode 21, the coil 1, and the diode 23, to the terminal 9. In the negative half cycle, hold-in currentflows from the terminal 9, through the diode 22, the coil 1 (in the same direction as forthe positive half cycle),the diode 20 andthe capacitor 16, to the terminal 9. This allows the capacitor 16to pass hold-in current in the reverse half cycle, instead of relying merely on the freewheel currentthrougnthe diode t7 of Figure 1.
Figure 3 shows an improvement on the previouslydescribed circuits. Components having the same functions as in Figures 1 and 2 have the same reference numerals as in those Figures. In this case a unidirectional supply on lines 25 and 26 is obtained from a bridge rectifier27 connected to the a.c. supply 2. Azener diode 28 and a series resistor 29 provide a regulated voltage across the charging circuit. The solenoid is now located between the positive line 25 and the anode of the thyristor7. The freewheel diode 17 is connected across the coil 1,as in Figure 1. An NPN transistor 30 is connected in series with the thyristor and solenoid circuit, the emitter of the transistor being connected, via a resistor 31, to the negative line 26.The base of the transistor is connected to the line 25 via a resistor32, and a zener diode 33 is connected between the base and the line 26.
The transistor 30 and its associated components form a constant current circuit, which limits the pull-in currentto an acceptable level, as described below. It is found thatthe mechanical life of a solenoid-operated device is dependent upon the pull-in velocity; the higherthe applied voltage, the shorterthe expected life ofthe device, due to the increased velocity. The constant current circuit can compensate for considerable increases in the supply voltage. The hold-in current is somewhat increased bythe presence ofthe circuit, but it is still small and perfectly acceptable. The diode 33 provides a fixed voltage on the base of the transistor30 overthe majority of each half cycle. The total current ofthe thyristor circuitry passes through theresistor3l,andthe resulting voltage biasesthe emitter ofthe transistor 30.A stable state is reached in which the emittervoltage issubstantiallythesame as the fixed voltage on the base. Hence, the value of the resistor 31 regulates the maximum pull-in current.
Due to the presence ofthe zener diode 28, the voltage causing the charging of the capacitor 11 no longer varies widely overthe period ofthe half cycle, as it does in the Figures 1 and 2 embodiments. The charging of the capacitor is therefore notasdepen- dent upon the point in the half cycle atwhich closure of the switch 6 is effected, so more repeatable pull-in times are obtainable.
The hold-in current in the circuit of Figure 3 flows through the coil 1, a diode 36, the capacitor 16, a resistor34in series therewith, and a resistor35in parallel with the series circuit. The magnitude ofthe hold-in current is therefore determined by the values ofthose components. Careful selection ofthe components ensures a very small power consumption atthe hold-in current level, and a smooth current waveform at pull-in and opening of the solenoid device. The level of electromagnetic interference generated by the circuit is therefore low.
Figure 4 shows a similarcircuittothat of Figure3, but rearranged to use a PNP transistor40 in place of the NPN transistor 30.
In any ofthe above circuits, optically sensitive devices, such as opto isolators or photothyristors, may be used in the thyristor circuit so that the solenoid device can be controlled directly via an optical fibre coupling.
The above-described circuits of the present invention have a number of advantages overthe prior arrangements of switches and economy resistors.
Firstly, although an a.c. supply is used, the solenoid device does not require a laminated core nor a shading coil, since no reversal ofthe magnetic field takes place. Secondly, the hold-in current can be considerably reduced, thereby allowing more compact construction ofthe coil and core. Thirdly, the inductance ofthe solenoid device is not significant, so the air gap in the magnetic system is not critical, as it is in an a.c.-energised device. Fourthly, if the solenoid device fails to pull in, only the normal low-value hold-in current will flow after the predetermined charging period has ended. In a conventional circuit, failure to pull in will meanthatthe pull-in current will continue to flow until the supply is switched off.This will result in overheating of the solenoid device which, if allowed to continue, could prove disastrous.
Itwill be apparent that a thyristor circuit as described above would not be suitable for energising a d.c. solenoid device from a d.c. supply, because complicated commutation circuitry would be required. Furthermore, reactive impedance in the solenoid coils clearly cannot be relied upon for reducing the hold-in current in a d.c. circuit. Atransistor ora gate-turn-offdevice might be used in placeofthe thyristor, butawasteful resistorwouldthen have to be used for reducing the coil hold-in current.
Asolenoid drive circuitforenergising a d.c. solenoid device from a d.c. supply without the need for an economy resistor will now be described with refer ence to FigureS ofthe drawings.
In this circuit the solenoid coil 1 is divided into two sections 1A and 1 B, which are electrically insulated from each other, but which are so wound and so located asto be in magnetically-aiding relationship.
One end 41 ofthe coil section 1A is connected to the positive terminal 42 of a d.c. supply 43. The opposite end 44 ofthe coil section 1 B is connected to the negative terminal 45 of the d.c. supply. The other end 46 ofthe coil section 1A is connected to the anode of a diode 47, the cathode of which is connected to the other end 48 ofthe coil section 1 B.
The emitter of a PNP transistor 49 is connected to the positive terminal 42, and its collector is connected to the end 48 ofthe coil section 1 B. The emitter of an
NPN transistor 50 is connected to the negative terminal 45, and its collector is connected to the end 46 of the coil section 1A.
Atiming circuit 51 comprises a resistor 52, a capacitor 53 and a resistor 54 connected in series between the d.c. terminals 42 and 45. The base of the transistor 49 is connected to a junction 55 between the resistor 52 and the capacitor 53, whilst the base ofthe transistor 50 is connected to a junction 56 between the capacitor 53 and the resistor 54. A resistor 57 is connected acrossthe capacitor 53.
In operation ofthe circuit, when the d.c. supply is switched on, the capacitor 53 begins to charge via the resistors 52 and 54. The charging current th rough the resistor 52 lowersthe potential ofthe base ofthe transistor49, which therefore becomes conductive and connects the end 48 ofthe coil section 1 B to the positive terminal 42. The charging current through the resistor 54 raises the potential ofthe base of the transisitor 50, which therefore becomes conductive and connectsthe end 46 ofthe coil section 1Ato the negative terminal 45.
Hence, while the transistors 49 and 50 are conduc tivethe ends41 and 48 ofthecoil sections are both connected to the positive terminal 42, whilstthe ends 44 and 46 are both connected to the negative terminal 45. The coil sections are therefore connected in parallel across the d.c. supply, and a relatively large currentflows through the coils causing the armature to pull in.
Meanwhile,the capacitor 53 is charging up, so the charging current is decreasing. The potential ofthe base ofthetransistor 49 is therefore rising, and the potential ofthe base of the transistor 50 is falling. After a period oftimefollowing switch-on, the length of which period is determined bythevalues of the capacitor 53 and the resistors 52 and 54, thetransistors 49 and 50 turn off, thereby isolating the ends of the coil sections from each other, exceptforthe path provided bythediode47.
Current now flows from the positive terminal 42, through the coil section 1 A, through the diode 47, and through the coil section 1 B, to the negative terminal 45. Since the coil sections are now connected in series across the d.c. supply, a relatively small hold-in currentflowsthroughthecoils.
When the d.c. supply is switched off, the capacitor 53 discharges through the resistor 57, readyforthe next period of energisation of the solenoid. The discharge circuit could be modified by inserting a further resistor (not shown) in series with the capacitor 53 and connecting a diode across that resistor, the resistor 57 being connected across the series circuit.
The polarity of the diode would be such that charging currentto the capacitor would flowthrough thefurther resistor but not th rough the diode. The further resistor would limitthecharging rateofthecapacitor53, thereby maintaining the parallel connection ofthe coil sections for a longer period. When the supply isturned off, the capacitor 53 would discharge through the diode and the resistor 57, so that the discharge rate is not affected by the further resistor. Rapid discharge, in readiness for subsequent re-energisation of the solenoid, would therefore still be obtained.
The above-described circuit, in which two coil sections are used, firstly in parallel for pull-in and then inseriesforhold-in,givesa ratio of pull-in powerto hold-in power of 4. This ratio can be substantially increased by increasing the number of coil sections, but this involves an increase in the complexity ofthe circuit.
Such a circuit, in which three coil sections are used, is shown in Figure6ofthedrawings. In FigureS, components having the same function as in Figure 5 have the same reference numerals as in the latter
Figure. The coil has an additional section 1 C, having ends 58 and 59. The coil sections are interconnected by diodes 60 and 61, similarto the diode 47 of Figure 5.
In this case, however, the collector ofthe transistor 49 is connected to the coil section ends 48 and 58 via diodes 62 and 63, respectively, whilst the collector of the transistor 50 is connected to the coil section ends 46 and 59 via diodes 64 and 65, respectively. The polarity of the diodes 62-65 is such that, when the transistors 49 and 50 are conductive, current flows from the positive terminal 42 to the negative terminal 45 through the coil sections in parallel, but when the transistors are non-conductive the coil setion ends 48 and 58 are isolated from each other and, similarly, the coil section ends 46 and 59 are isolated from each other, so thatthe required series connection can be achieved, using the diodes 60 and 61.
Further coil sections can be added, using further diodes in the same manner as in the Figure 6 embodiment.
Claims (19)
1. Asolenoid drive circuitfor energising the coil of a solenoid device from a power supply, the circuit comprising switching means to cause a relatively high currentto pass through the coil from the power supply in a pull-in mode and a relatively lowcurrentin a hold-in mode; and a timing circuit including first capacitance means which receives charging current from the powersupply, theswitching means being operable to switch from the pull-in mode to the hold-in mode when the charge on the first capacitance means reaches a predetermined level.
2. A circuit as claimed in claim 1, for energising the coil from alternating current power supply, wherein the switching means comprises a thyristorfor connec tionbetweenthe power supply and the solenoimOboil; wherein the timing circuit includes gating means which is operative to fire the thyristor during successive supply cycles dlw hat it allows the relatively high currentto pass through the coil in said pull-in mode and thereafter to inhibitfiring ofthe thyristor; and wherein an auxiliary current path bypassing the thyristor is provided for passing the
relatively low current through the coil when firing of the thyristor is inhibited.
3. Acircuitasclaimed in claim 2,wherein the gating means produces a gating signal forfiring the thyristor in response to pulses of charging current flowing into the first capacitance means during successive power supply cycles, the charging current pulses being of insufficent magnitude to cause firing ofthethyristorafterthecharge has reached the predetermined level.
4. A circuit as claimed in claim 2 or claim 3, wherein the auxiliary current path includesthetiming circuit.
5. A circuit as claimed in claim 2, claim 3 or claim 4, wherein the auxiliary current path includes second capacitance means which is connected across the thyristor.
6. A circuit as claimed in any one of claims 2-5, including freewheel diode means connected across the coil.
7. A circuit as claimed in any one of claims 2-5, including a first diode bridge, two opposite corners of which are connected betweenthethyristorandthe power supply, and the other corners of which are connected across the coil.
8. A circuit as claimed in any one of claims 2-7, including a second diode bridge which feeds a unidirectional currentto thethyristor and the coil from the power supply.
9. Acircuitasclaimed inclaim8,including means for providing a regulated voltage from which the first capacitance means is charged.
10. A circuit as claimed in any one of claims 2-9,
including constant current means for limiting the magnitude of said relatively high current.
11. A circuit as claimed in claim 10, wherein the constant current means comprises a transistor the collector and emitter electrodes ofwhich are connected in series with the thyristor and the coil; and a zener diode connected to the base ofthe transistor to limit the base/em itter voltage to a predetermined level.
12. A circuit as claimed in claim 1,forenergising the coil from a direct current power supply, wherein the coil is divided into a plurality of sections which are electrically isolated from each other; and wherein the switching means is operative to connectthecoil sections in parallel across the direct current supply in the pull-in mode and to connectthem in series across the direct current supply in the hold-in mode.
13. A circuit as claimed in claim 12, wherein there are first and second of said coil sections, each having first and second ends; wherein the first end ofthe first coil section and the second end ofthe second coil section are connected to first and second poles ofthe power supply, respectively; wherein a first switch of the switching means is connected between the first power supply pole and thefirstend ofthe second coil section; wherein a second switch ofthe switching means is connected between the second power supplypole and the second endofthefirstcoil section; and wherein diode means interconnects the second end ofthe first coil section and the first end of the second coil section.
14. A circuit as claimed in claim 13, wherein the first and second switches comprise transistors of complementary conductivitytype, the emitter electrodes of which are connected to the first and second power supply poles, respectively.
15. A circuit as claimed in claim 14, wherein the timing circuit is connected to the base electrodes of the two transistors.
16. Acircuitasclaimed in claim 15,whereinthe timing circuit comprisesfirst and second resistance means connected between the emitter and base electrodes ofthe first and second transistors, respectively, said first capacitance means being connected in series between the base electrodes.
17. A circuit as claimed in claim 16, including discharge resistance means connected across the first capacitance means.
18. Acircuitas claimed in any one of claims 14-16, including atleastone additional coil section; wherein the collector electrode of each transistor is connected to each respective end ofthe coil sections via diode means.
19. A circuitfor energising the coil of a solenoid device from a power supply, substantially as hereinbefore described with reference to the accompanying drawings.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB08602481A GB2170669A (en) | 1985-02-05 | 1986-01-31 | Solenoid energisation circuit |
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB858502856A GB8502856D0 (en) | 1985-02-05 | 1985-02-05 | Solenoid energisation circuit |
| GB08602481A GB2170669A (en) | 1985-02-05 | 1986-01-31 | Solenoid energisation circuit |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| GB8602481D0 GB8602481D0 (en) | 1986-03-05 |
| GB2170669A true GB2170669A (en) | 1986-08-06 |
Family
ID=26288763
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| GB08602481A Withdrawn GB2170669A (en) | 1985-02-05 | 1986-01-31 | Solenoid energisation circuit |
Country Status (1)
| Country | Link |
|---|---|
| GB (1) | GB2170669A (en) |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP0671747A2 (en) * | 1994-03-11 | 1995-09-13 | Siemens Aktiengesellschaft | Circuit with reduced direct current |
| WO2000065179A1 (en) * | 1999-04-21 | 2000-11-02 | Quante Aktiengesellschaft | Barring configuration and security system comprising a barring configuration |
Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB1158035A (en) * | 1967-11-17 | 1969-07-09 | Madeburger Armaturenwerke Karl | Rectifier Circuits |
| GB1482815A (en) * | 1973-10-25 | 1977-08-17 | Kromschroeder Ag G | Circuit arrangement for the switching over of an electromagnet from its actuating current to a holding current |
| GB1550141A (en) * | 1975-10-02 | 1979-08-08 | Sperry Rand Corp | Solid state switching systems for energizing solenoids |
| GB1552267A (en) * | 1978-03-23 | 1979-09-12 | Coventry Factors Ltd | Operating circuit for a coil-actuated relay contactor or switch |
| GB1576822A (en) * | 1976-03-19 | 1980-10-15 | Sevcon Ltd | Electromagnetically operated contactors |
-
1986
- 1986-01-31 GB GB08602481A patent/GB2170669A/en not_active Withdrawn
Patent Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB1158035A (en) * | 1967-11-17 | 1969-07-09 | Madeburger Armaturenwerke Karl | Rectifier Circuits |
| GB1482815A (en) * | 1973-10-25 | 1977-08-17 | Kromschroeder Ag G | Circuit arrangement for the switching over of an electromagnet from its actuating current to a holding current |
| GB1550141A (en) * | 1975-10-02 | 1979-08-08 | Sperry Rand Corp | Solid state switching systems for energizing solenoids |
| GB1576822A (en) * | 1976-03-19 | 1980-10-15 | Sevcon Ltd | Electromagnetically operated contactors |
| GB1552267A (en) * | 1978-03-23 | 1979-09-12 | Coventry Factors Ltd | Operating circuit for a coil-actuated relay contactor or switch |
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP0671747A2 (en) * | 1994-03-11 | 1995-09-13 | Siemens Aktiengesellschaft | Circuit with reduced direct current |
| EP0671747A3 (en) * | 1994-03-11 | 1995-11-29 | Siemens Ag | Circuit with reduced direct current. |
| WO2000065179A1 (en) * | 1999-04-21 | 2000-11-02 | Quante Aktiengesellschaft | Barring configuration and security system comprising a barring configuration |
Also Published As
| Publication number | Publication date |
|---|---|
| GB8602481D0 (en) | 1986-03-05 |
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