CA2461332C - Wide input voltage range surge suppressor - Google Patents
Wide input voltage range surge suppressor Download PDFInfo
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- CA2461332C CA2461332C CA2461332A CA2461332A CA2461332C CA 2461332 C CA2461332 C CA 2461332C CA 2461332 A CA2461332 A CA 2461332A CA 2461332 A CA2461332 A CA 2461332A CA 2461332 C CA2461332 C CA 2461332C
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- 239000003990 capacitor Substances 0.000 claims abstract description 60
- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical compound [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 claims abstract description 4
- 229910052710 silicon Inorganic materials 0.000 claims abstract description 4
- 239000010703 silicon Substances 0.000 claims abstract description 4
- 238000011144 upstream manufacturing Methods 0.000 claims abstract 3
- 230000008859 change Effects 0.000 description 6
- 230000001629 suppression Effects 0.000 description 6
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- 238000001914 filtration Methods 0.000 description 3
- 230000004044 response Effects 0.000 description 3
- 238000012360 testing method Methods 0.000 description 3
- 230000001052 transient effect Effects 0.000 description 3
- 101000668165 Homo sapiens RNA-binding motif, single-stranded-interacting protein 1 Proteins 0.000 description 2
- 102100039692 RNA-binding motif, single-stranded-interacting protein 1 Human genes 0.000 description 2
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- 239000004020 conductor Substances 0.000 description 2
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- 238000004146 energy storage Methods 0.000 description 2
- 230000008878 coupling Effects 0.000 description 1
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Classifications
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- H—ELECTRICITY
- H02—GENERATION; CONVERSION OR DISTRIBUTION OF ELECTRIC POWER
- H02H—EMERGENCY PROTECTIVE CIRCUIT ARRANGEMENTS
- H02H9/00—Emergency protective circuit arrangements for limiting excess current or voltage without disconnection
- H02H9/005—Emergency protective circuit arrangements for limiting excess current or voltage without disconnection avoiding undesired transient conditions
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Abstract
The present invention is directed to a wide input voltage range surge suppressor. It includes a series circuit for attachment to an upstream AC power input, and to a downstream load. There is a nonlinear low pass L-C filter having an inductor (and in some preferred embodiments, a low Q linear inductor) and a diode bridge, wherein the diode bridge includes at least one large value capacitor. There are two or three electrolytic capacitors of the nonlinear low pass L-C filter diode bridge in preferred embodiments. There is also a two section high pass filter connected to the electrolytic capacitor. This two section high pass filter has at least two diversely rated capacitors and at least three diversely rated resistors. A voltage offset diode is connected to the two section high pass filter and at least one electronic switch is connected to the voltage offset diode, with at least one capacitor connected to the electronic switch. The electronic switch is preferably a silicon controlled rectifier (SCR) switch. In some preferred embodiments of the present invention, wide input voltage range surge suppressor there is at least one capacitor connected to the electronic switch and it is at least one electrolytic capacitor of the nonlinear low pass L-C filter diode bridge. In addition to the foregoing, the present invention wide input voltage range surge suppressor electronic switch includes at least one series resistor for current drive balance assurance.
Description
WIDE INPUT VOLTAGE RANGE SUR(JE SUPPRESSOR
BACKGROUND OF THE INVENTION
. 1. Field of the Invention The present invention relates to power line surge suppressers and, more specifically, to surge suppressers which are responsive to a wide input voltage range, e. g., in a range of les s than 100 volts to higher than 250 volts.
BACKGROUND OF THE INVENTION
. 1. Field of the Invention The present invention relates to power line surge suppressers and, more specifically, to surge suppressers which are responsive to a wide input voltage range, e. g., in a range of les s than 100 volts to higher than 250 volts.
2. Information Disclosure Statement Electric and electronic loads receiving power from an external grid is sometimes subjected to high voltage surges. Such surges may arise from inductive loads, lightning strikes or other phenomenon, and may cause damage to or even destroy electric and electronic equipment and devices. n . , The highest potential transient spike voltages are short in duration, typically tens of microseconds. These high potential strikes rnay have voltages in the ranges of many thousands of volts, at currents of many thousands of amperes. Such high voltages tend to overstress electronic equipment, components, motors, etc. creating unwanted and hazardous conditions. The high potentials and high current flow cause such drastic stress that permanent damage or destructian results.
In response to these problems, power main frequency isolation transformers in L7C power supplies were utilized to obtain energy from the AC power :main to isolate power main voltage from the loads for surge protection. However, these devices were costly, Iarge and heavy.
to In the alternative, to reduce costs, weight and size, switched-mode voltage regulators have been utilized, but these are not fully reliable and may themselves be damaged by high-potential surges. Line surge suppressors have also been utilized but have been unreliable when subjected to lightning storm strikes.
United States Patent No. 6,226,162 describes a surge suppression network for single phase and multiphase AC systems which has a voltage clamping device connected in series with a gated crowbar device across the supply voltage in parallel with the load to be protected. A
trigger circuit gates the crowbar device on in response to a specified rate of change of the supply voltage indicative of a surge. For higher levels of surge current shunting, pluralities of clamping devices and crowbar devices can be connected in paxallel with a: single trigger circuit simultaneously turning on all of the crowbar devices for each phase. For crowbar devices such_as TRIACs with different response characteristics to positive and negative surges and for unipolar devices such as SCRs, io positive and negative subnetworks are connected in anti-parallel across the load.
United States Patent No. 5,610,793 describes a three-stage surge protection circuit. The surge protection circuit includes input terminals for connection to an electrical power supply system and output terminals for connection to equipment to be protected. The three stages comprise: a surge dissipation stage coupled to the input terminals for storing a~~d _4_ dissipating transient surge energy across t:he input terminals; a current limiting stage comprising a pair of inductors, each of which is coupled in series to a respective conductor from said input terminals, for limiting current surges; and a voltage clamping stage comprising an avalanche diode for accurately clamping the voltage to be supplied to the protected electrical equipment to a predetermined level. The surge protection circuit of the present invention can also be provided in a configuration for protecting electrical equipment powered by a three conductor and/or three-phase power system.
to United States Patent No. 4,870,534 to the same inventor herein describes a surge suppressor for repeatedly protecting a Ioad against surges occurring an AC power mains from lightning surges or the like. It comprises a first series circuit having a first inductance and a first alternating voltage limiter, including at leavst a first capacitance and a bidirectionally conductive rectifier circuit, coupled between first and second input terminals. The first inductance conducts substantially all of _5_ the current supplied from the A-C power mains. A second series circuit comprising a second inductance and second alternating voltage limiter, including at least a second capacitance and a second bidirectionally conductive rectifier circuit, is coupled across the first alternating voltage limner and is coupled to first arid second output terminals. The first series circuit is arranged for limiting surge currents and voltage excursions passed to the second series circuit to first levels while the second series circuit is arranged for further limiting surge currents and voltage excursions passed to the output terminals to second levels less to . than first levels.
United States Fatent No. 4,870,528 to the same inventor hereiin describes a surge suppressor which comprises a first series circuit having a first inductance and a first alternating voltage limner, including at least a first capacitance and a bidirectionally conductive rectifying circuit for charging the first capacitance, coupled between first and second input terminals for iirniting surge currents and voltage excursions coupled to first and second load output terminals. The first alternating voltage limiter further comprises a sensing circuit for sensing at least one of the charging current supplied to and the voltage developed across the fast capacitance. An auxiliary energy storage circuit and a normally open switching device responsive to fihe sensing circuit are provided for coupling the auxiliary energy storage circuit across the first capacitance during high energy surge conditions.
Notwithstanding the prior art, the present invention is neither taught nor rendered obvious thereby.
SUMMARS~ OF THE INVENTION
The present invention is directed toJa wide input voltage range surge suppresser device. It includes a series circuit means, with a plurality of components, for installation between an AC power input and a downstream load. These components include a nonlinear low pass L-C
filter having an inductor and a diode bridge, wherein the diode bridge includes at least one large value capacitor, said filter adapted for attachment to an AC power input. There are two electrolytic capacitors of the nonlinear Iow pass L-C filter diode bridge in preferred embodiments. These electrolytic capacitors) have a rating within the range of about 50 microfarads to about 400 microfarads. The low pass L-C filter diode bridge rectif er diodes are generally rated in the range of about 3 amps, 400 volts to about 6 amps, 800 volts.
There is a two section high pass filter connected to the electrolytic capacitor. This high pass f lter has at least two capacitors, preferably diversely rated, and at least three resistors, preferably diversely rated.
to The two section high pass filter includes at least one capacitor having a rating within the range of about 0.05 microfarads-to about 0.5 microfarads, and at least a second capacitor having a rating within the range of about 0.1 microfarads to about 1.0 microfarads. Preferably, the two section high pass filter includes a resistor having a rating within the range of about 100 ohms to about 400 ohms, and at least a second resistor having a rating within the range of about 20 ohms to about 200 _g_ ohms, and at least a third resistor having a rating within the range of about 10 ohms to about 200 ohms.
An optional, but preferred voltage offset diode is connected to the two section high pass filter and at least one electronic switch is connected to the voltage offset diode, with at least one capacitor connected to the electronic switch. The electronic switch is preferably a silicon controlled rectifier (SCR) switch In preferred embodiments of the present invention wide input voltage range surge suppressor there is at least one capacitor connected to the electronic switch and it is at least one electrolytic capacitor of the nonlinear low pass L-C filter diode bridge.
In addition to the foregoing, the present invention wide input voltage range surge suppressor electronic switch includes at least one series resistor for current drive balance assurance.
Tn some embodiments ~f the present invention, the capacitors) connected to the electronic switch is separate from the one electrolytic _9_ capacitors) of the nonlinear low pass L-C filter diode bridge and is contained within a separate bridge.
BRIEF DESCRIPTION OF THE DRAWINGS
The present invention should be more fully understood when the specification herein is taken in conjunction with the drawings appended hereto wherein:
Figure 1 illustrates a block diagram of the present invention showing the various functional components utilized therein;
1o . Figure 2 shows a wiring diagram of one preferred embodiment of the present invention; and, Figures 3; 4 and 5 show test results of the present invention using.
the embodiment shown Figure 2.
DETAILED DESCRIPTION OF THE PRESENT IKON
Most electronic equipment is powered from "switch mode" power supplies: These power supplies generally take their power from the peak y _ of the power wave, making them particularly susceptible to surges, which exceed the peak voltage of the power wave.
The present invention power line surge suppressor is directed to this problem and only permits an extremely small amount of surge energy through it to protected equipment, making it particularly effective for protecting such switch mode power supplies. Uniquely, in the present invention device, the Iow surge energy let-through is substantially independent ofthe absolute applied voltage, unlike fixed clamping level surge suppressors. An input voltage range of at least 3 to 1 is achieved l0 with no surge performance degradation, making the present invention surge suppressor very effective in "brownout" and other wide input voltage range conditions.
Furthermore, the present invention device is not "sacrificial", that is, it does not "wear out" with use, giving products using this technology the benefit of very long life in extreme electrical environments.
Power line surges within a building may be as large as 6,000 Volts, 3,000 Amperes, with a duration of SO microseconds, according to the industry standard ANSI C62.41. UL uses 6,000 Volts, 500 Amps for their UL1449 safety duty factor (endurance) testing, and for establishing their SVR (Suppressed Voltage~Rating). Power Line surge suppressors should serve the purpose of reducing such electrical surges to benign levels of voltage, current and duration (energy).
Most equipment today is powered from switch-mode power supplies. These supplies take their power .from the peak of the power l0 wave, where they present a very low impedance to said power wave during the peak period of the wave. This is important for understanding the significant advantages of the present iizvention device.
Three recent situations make conventional fixed voltage surge clamping products relatively ineffective in light of switch-mode supply characteristics.
First, utility companies Lower their power line voltage during "brown-out" situations to conserve available electrical power. This'., voltage may be 108 Volts 12MS (152 Volts peak), or even Lower. Since fixed clamping level surge protection devices must be set to clamp at a voltage higher than the highest expected voltage (typically 10% above normal, or 132 Volts RMS, or 187 Volts peak), plus the clamping component tolerance, the typical clamping component is rated for 150 Volts ItMS (21.2 Volts peak). With a 10% component tolerance, the clamping voltage would range from 135 to 165 Volts RMS (190 to 233 l0 Volts peak). In the brown out scenario just described, the power line Voltage is 108 Volts RMS, and.fixed clamping component is 165 Volts RMS, and, with the prior art surge suppressors, absolutely no surge suppression takes place until after a surge voltage increment of about 80 Volts peak! Such a large voltage increment before any surge suppression even starts, results in very large currents flowing into the "protected"
power supply, damaging or putting these supplies under severe stress!
Second, During rolling blackouts, very large surges are created as the magnetic fields around all of the current carrying wires collapse.
These wide area regions of multiple surges put significant stress on power supplies and surge components alike, making effective, reliable suppression increasingly important.
Third, some newer equipment is being designed to operate from voltages that vary from 85 Volts RIV1S to 265 Volts RNiS. Fixed clamping components for surge protection of this equipment are virtually useless over this wide voltage range.
to The present invention overcomes all of the foregoing shortcomings ofthe prior art fixed voltage surge protection devices.
The block diagram of Figure 1 shows the components of the present invention device, which has the unique capability of operating from 85 Volts :l2MS to 265 Volts luVIS with effective dynamic surge energy suppression throughout the operating voltage range.
The surge suppressor of the present invention includes a f.-~rst non-linear low pass L-C filter {10) having a low Q linear inductor 3, diode bridge 5, and electrolytic capacitors 7 and 9 within the bridge. A
capacitor 7 within the bridge 5 charges to the peak voltage of the power wave. The Ioad on the capacitor 7 is small, so that the peak voltage value is substantially maintained across the capacitor 7 during normal operation. Under normal operation {no significant surge or brown out), the filtering action of the inductor 3 and capacitor 7 are minimal, since the filter capacitor 7 maintains its charge and has no impact on the power 1o signal due to the peak detection action of the diode bridge circuit 5.
In the event of a surge which exceeds the peak voltage on the capacitor 7; full L-C filtering action takes place since the capacitor 7 is now~effectively in the circuit, the supply voltage having exceeded the capacitor voltage. This filtering action has the effect of integrating and slowing down the leading edge of the surge. Due to the integration nature ofthe capacitor 7, the incremental voltage change caused by the surge current is a measure of the surge energy in Joules (1/2 C~ V2 ) passing through the inductor. The rate of change of this incremental voltage on the capacitor 7 is an indication of the surge current.
A two section high pass filter 11 is connected across the peak detecting capacitor to detect the rate of voltage to see if this rate df change is large enough to pose a potential. risk. A large rate of change will pass readily through the two section high pass filter 11, while a Iow rate of change will nat. An. optional, but preferred, small voltage offset to 13 (a diode) is subsequently used to prevent false triggering due to normal power voltage turn-on conditions. After differentiation of the surge voltage across the capacitor, the remaining voltage at the output of the high pass filter 11 is applied to one or more electronic switches l S
(SCRs); and if the voltage is large enough, the SCRs) will conduct. The SCRs) are used to connect uncharged capacitors also located within, the same or another bridge, into the circuit, being effectively placed directly -l6-across the incoming surge, which has the effect of inverting the surge and reducing it to a benign level, due to the low impedance of the , capacitors, thus protecting the load 17.
Referring to Figure 2, a preferred embodiment wiring diagram is shown. Capacitor CI is inside tie diode bridge D3, D6, D7, D8. This capacitor will charge up to the peak ofthe power wave voltage; and maintain that voltage since RI discharges very little of the voltage during each power wave cycle. Any voltage (such as a surge voltage) which exceeds the peak of the normal power wave voltage appears across C1 to and is transferred to the high pass network consisting of C5, R10, R8, C6, R3. This two section high pass filter is selected to provide sufficient current to actiYvate the SCRs, SCRI and SCR2.
The SCRs in this example require up to 30 ma each to turn on.
Since there may be an unbalance in their characteristics, series resistors R4 and R5 are used to assure balanced current drive to the SCRs.
Assuming a 3 to 1 overdrive current (180 ma. total), and driving from a . _17_ low enough impedance to assure adequate drive current for faster turn-on, R10 may be established at about 200 Ohms for a surge inversion voltage of 100 Volts for a worst case 6,000 Volt surge. The values for each of the components shown in. Figure 2 are as follows:
PART NO. DESCRIPTIdN AND VALUE
Capacitors C1 120 mfd, 450 volt C2 120 mfd, 450 volt C3 120 mfd, 450 volt .
C4 1 mfd, 250 volt C5 ~ 0.1 mfd, 400 volt C6 0.22 mfd, 50 volt Diodes Dl LED
D2 3 amp, 400 volt rectifier diode D3 6 amp, 800 volt rectifier diode D4 15 volt, 1 watt Zener diode DS 1 amp, 400 volt rectifier diode D6 6 amp, 800 volt rectifier diode D7 6 amp, 800 volt rectifier diode D8 6 amp, 800 volt rectifier diode Inductors L1 2.2 microhenry L2 2:2 microhenry L3 100 microhenry Resistors Rl 68k; 2 watt R2 . 390 ohm, 5 watt R3 47 ohm R4 47 ohm 1 s RS 47 ohm R6 390 ohm, 5 watt R7 5 ohm, 5 watt R8 47 ohm R9 2.7k R10 180 ohm, 1 watt S SCRs ' SCRI 20 amp, 600 volt SCR2 20 amp, 600 volt Utilizing the present invention device illustrated in Figure 2 above, tests were made over a range of voltages with a SOOamp surge to show the efFcacy of the present invention for varied voltages: Figures 3, 4 and 5 show the results.
in Figures 3, 4 and 5, respectively, waveforms are shown for 85 Volts RMS, 120 Volts RMS, and 240 Yolts RMS, for a 6 kV, 500 amp surge. In each of these Figures, the applied surge voltage and the let-through voltage are plotted against time. In Figure 3, the peak let-through voltage was about 0.25 kV, for Figure 4, about 0.29 kV and for Figure 5, about 0.46 kV, showing the consistent present invention surge suppression performance independent of the wide input voltage range. It can be seen that, while the incoming surge voltage exceeds the peak of the power wave for a period greater than 100 microseconds, the iet-through voltage of this invention exceeds the peak voltage ofthe power wave for less than 6 microseconds in every case from $5 VAC to 240 VAC, thereby greatly diminishing the surge energy transferred to the to protected load.
The essence of the present invention is the use of a L-C low pass input filter to act as an energy integrator and surge current Iirmiter followed by a two section R-C filter. The two section high pass filter selects out surge energy levels large enough to do damage; while ignoring normal power line voltage conditions. When the surge energy levels are high enough, a semiconductor switching circuit is enabled to effectively invert surge energy before it can do any harm. Passive and active components are used which all operate within their transient ratings, so no degradation takes place during a surge, and the circuit has no inherent failure mode (non-sacrificial.
This circuit is an improvement over prior art in that it eliminates controlling Zener diodes and, thus, eliminates circuitry that limited the voltage range of optimum protection. The improved circuit of the present invention device functions optimally and essentially independently of the supply voltage, giving it superior performance independent of brownouts and enabling optimum protection for wide input voltage range equipment using switch-mode power supplies.
Obviously, numerous modifications and variations of the present invention are possible in light of the above teachings. It is therefore understood that within the scope of the appended claims, the invention i5 may be practiced otherwise than as specifically described herein, for example, the present invention suppressor could' be employed in three phase applications.
In response to these problems, power main frequency isolation transformers in L7C power supplies were utilized to obtain energy from the AC power :main to isolate power main voltage from the loads for surge protection. However, these devices were costly, Iarge and heavy.
to In the alternative, to reduce costs, weight and size, switched-mode voltage regulators have been utilized, but these are not fully reliable and may themselves be damaged by high-potential surges. Line surge suppressors have also been utilized but have been unreliable when subjected to lightning storm strikes.
United States Patent No. 6,226,162 describes a surge suppression network for single phase and multiphase AC systems which has a voltage clamping device connected in series with a gated crowbar device across the supply voltage in parallel with the load to be protected. A
trigger circuit gates the crowbar device on in response to a specified rate of change of the supply voltage indicative of a surge. For higher levels of surge current shunting, pluralities of clamping devices and crowbar devices can be connected in paxallel with a: single trigger circuit simultaneously turning on all of the crowbar devices for each phase. For crowbar devices such_as TRIACs with different response characteristics to positive and negative surges and for unipolar devices such as SCRs, io positive and negative subnetworks are connected in anti-parallel across the load.
United States Patent No. 5,610,793 describes a three-stage surge protection circuit. The surge protection circuit includes input terminals for connection to an electrical power supply system and output terminals for connection to equipment to be protected. The three stages comprise: a surge dissipation stage coupled to the input terminals for storing a~~d _4_ dissipating transient surge energy across t:he input terminals; a current limiting stage comprising a pair of inductors, each of which is coupled in series to a respective conductor from said input terminals, for limiting current surges; and a voltage clamping stage comprising an avalanche diode for accurately clamping the voltage to be supplied to the protected electrical equipment to a predetermined level. The surge protection circuit of the present invention can also be provided in a configuration for protecting electrical equipment powered by a three conductor and/or three-phase power system.
to United States Patent No. 4,870,534 to the same inventor herein describes a surge suppressor for repeatedly protecting a Ioad against surges occurring an AC power mains from lightning surges or the like. It comprises a first series circuit having a first inductance and a first alternating voltage limiter, including at leavst a first capacitance and a bidirectionally conductive rectifier circuit, coupled between first and second input terminals. The first inductance conducts substantially all of _5_ the current supplied from the A-C power mains. A second series circuit comprising a second inductance and second alternating voltage limiter, including at least a second capacitance and a second bidirectionally conductive rectifier circuit, is coupled across the first alternating voltage limner and is coupled to first arid second output terminals. The first series circuit is arranged for limiting surge currents and voltage excursions passed to the second series circuit to first levels while the second series circuit is arranged for further limiting surge currents and voltage excursions passed to the output terminals to second levels less to . than first levels.
United States Fatent No. 4,870,528 to the same inventor hereiin describes a surge suppressor which comprises a first series circuit having a first inductance and a first alternating voltage limner, including at least a first capacitance and a bidirectionally conductive rectifying circuit for charging the first capacitance, coupled between first and second input terminals for iirniting surge currents and voltage excursions coupled to first and second load output terminals. The first alternating voltage limiter further comprises a sensing circuit for sensing at least one of the charging current supplied to and the voltage developed across the fast capacitance. An auxiliary energy storage circuit and a normally open switching device responsive to fihe sensing circuit are provided for coupling the auxiliary energy storage circuit across the first capacitance during high energy surge conditions.
Notwithstanding the prior art, the present invention is neither taught nor rendered obvious thereby.
SUMMARS~ OF THE INVENTION
The present invention is directed toJa wide input voltage range surge suppresser device. It includes a series circuit means, with a plurality of components, for installation between an AC power input and a downstream load. These components include a nonlinear low pass L-C
filter having an inductor and a diode bridge, wherein the diode bridge includes at least one large value capacitor, said filter adapted for attachment to an AC power input. There are two electrolytic capacitors of the nonlinear Iow pass L-C filter diode bridge in preferred embodiments. These electrolytic capacitors) have a rating within the range of about 50 microfarads to about 400 microfarads. The low pass L-C filter diode bridge rectif er diodes are generally rated in the range of about 3 amps, 400 volts to about 6 amps, 800 volts.
There is a two section high pass filter connected to the electrolytic capacitor. This high pass f lter has at least two capacitors, preferably diversely rated, and at least three resistors, preferably diversely rated.
to The two section high pass filter includes at least one capacitor having a rating within the range of about 0.05 microfarads-to about 0.5 microfarads, and at least a second capacitor having a rating within the range of about 0.1 microfarads to about 1.0 microfarads. Preferably, the two section high pass filter includes a resistor having a rating within the range of about 100 ohms to about 400 ohms, and at least a second resistor having a rating within the range of about 20 ohms to about 200 _g_ ohms, and at least a third resistor having a rating within the range of about 10 ohms to about 200 ohms.
An optional, but preferred voltage offset diode is connected to the two section high pass filter and at least one electronic switch is connected to the voltage offset diode, with at least one capacitor connected to the electronic switch. The electronic switch is preferably a silicon controlled rectifier (SCR) switch In preferred embodiments of the present invention wide input voltage range surge suppressor there is at least one capacitor connected to the electronic switch and it is at least one electrolytic capacitor of the nonlinear low pass L-C filter diode bridge.
In addition to the foregoing, the present invention wide input voltage range surge suppressor electronic switch includes at least one series resistor for current drive balance assurance.
Tn some embodiments ~f the present invention, the capacitors) connected to the electronic switch is separate from the one electrolytic _9_ capacitors) of the nonlinear low pass L-C filter diode bridge and is contained within a separate bridge.
BRIEF DESCRIPTION OF THE DRAWINGS
The present invention should be more fully understood when the specification herein is taken in conjunction with the drawings appended hereto wherein:
Figure 1 illustrates a block diagram of the present invention showing the various functional components utilized therein;
1o . Figure 2 shows a wiring diagram of one preferred embodiment of the present invention; and, Figures 3; 4 and 5 show test results of the present invention using.
the embodiment shown Figure 2.
DETAILED DESCRIPTION OF THE PRESENT IKON
Most electronic equipment is powered from "switch mode" power supplies: These power supplies generally take their power from the peak y _ of the power wave, making them particularly susceptible to surges, which exceed the peak voltage of the power wave.
The present invention power line surge suppressor is directed to this problem and only permits an extremely small amount of surge energy through it to protected equipment, making it particularly effective for protecting such switch mode power supplies. Uniquely, in the present invention device, the Iow surge energy let-through is substantially independent ofthe absolute applied voltage, unlike fixed clamping level surge suppressors. An input voltage range of at least 3 to 1 is achieved l0 with no surge performance degradation, making the present invention surge suppressor very effective in "brownout" and other wide input voltage range conditions.
Furthermore, the present invention device is not "sacrificial", that is, it does not "wear out" with use, giving products using this technology the benefit of very long life in extreme electrical environments.
Power line surges within a building may be as large as 6,000 Volts, 3,000 Amperes, with a duration of SO microseconds, according to the industry standard ANSI C62.41. UL uses 6,000 Volts, 500 Amps for their UL1449 safety duty factor (endurance) testing, and for establishing their SVR (Suppressed Voltage~Rating). Power Line surge suppressors should serve the purpose of reducing such electrical surges to benign levels of voltage, current and duration (energy).
Most equipment today is powered from switch-mode power supplies. These supplies take their power .from the peak of the power l0 wave, where they present a very low impedance to said power wave during the peak period of the wave. This is important for understanding the significant advantages of the present iizvention device.
Three recent situations make conventional fixed voltage surge clamping products relatively ineffective in light of switch-mode supply characteristics.
First, utility companies Lower their power line voltage during "brown-out" situations to conserve available electrical power. This'., voltage may be 108 Volts 12MS (152 Volts peak), or even Lower. Since fixed clamping level surge protection devices must be set to clamp at a voltage higher than the highest expected voltage (typically 10% above normal, or 132 Volts RMS, or 187 Volts peak), plus the clamping component tolerance, the typical clamping component is rated for 150 Volts ItMS (21.2 Volts peak). With a 10% component tolerance, the clamping voltage would range from 135 to 165 Volts RMS (190 to 233 l0 Volts peak). In the brown out scenario just described, the power line Voltage is 108 Volts RMS, and.fixed clamping component is 165 Volts RMS, and, with the prior art surge suppressors, absolutely no surge suppression takes place until after a surge voltage increment of about 80 Volts peak! Such a large voltage increment before any surge suppression even starts, results in very large currents flowing into the "protected"
power supply, damaging or putting these supplies under severe stress!
Second, During rolling blackouts, very large surges are created as the magnetic fields around all of the current carrying wires collapse.
These wide area regions of multiple surges put significant stress on power supplies and surge components alike, making effective, reliable suppression increasingly important.
Third, some newer equipment is being designed to operate from voltages that vary from 85 Volts RIV1S to 265 Volts RNiS. Fixed clamping components for surge protection of this equipment are virtually useless over this wide voltage range.
to The present invention overcomes all of the foregoing shortcomings ofthe prior art fixed voltage surge protection devices.
The block diagram of Figure 1 shows the components of the present invention device, which has the unique capability of operating from 85 Volts :l2MS to 265 Volts luVIS with effective dynamic surge energy suppression throughout the operating voltage range.
The surge suppressor of the present invention includes a f.-~rst non-linear low pass L-C filter {10) having a low Q linear inductor 3, diode bridge 5, and electrolytic capacitors 7 and 9 within the bridge. A
capacitor 7 within the bridge 5 charges to the peak voltage of the power wave. The Ioad on the capacitor 7 is small, so that the peak voltage value is substantially maintained across the capacitor 7 during normal operation. Under normal operation {no significant surge or brown out), the filtering action of the inductor 3 and capacitor 7 are minimal, since the filter capacitor 7 maintains its charge and has no impact on the power 1o signal due to the peak detection action of the diode bridge circuit 5.
In the event of a surge which exceeds the peak voltage on the capacitor 7; full L-C filtering action takes place since the capacitor 7 is now~effectively in the circuit, the supply voltage having exceeded the capacitor voltage. This filtering action has the effect of integrating and slowing down the leading edge of the surge. Due to the integration nature ofthe capacitor 7, the incremental voltage change caused by the surge current is a measure of the surge energy in Joules (1/2 C~ V2 ) passing through the inductor. The rate of change of this incremental voltage on the capacitor 7 is an indication of the surge current.
A two section high pass filter 11 is connected across the peak detecting capacitor to detect the rate of voltage to see if this rate df change is large enough to pose a potential. risk. A large rate of change will pass readily through the two section high pass filter 11, while a Iow rate of change will nat. An. optional, but preferred, small voltage offset to 13 (a diode) is subsequently used to prevent false triggering due to normal power voltage turn-on conditions. After differentiation of the surge voltage across the capacitor, the remaining voltage at the output of the high pass filter 11 is applied to one or more electronic switches l S
(SCRs); and if the voltage is large enough, the SCRs) will conduct. The SCRs) are used to connect uncharged capacitors also located within, the same or another bridge, into the circuit, being effectively placed directly -l6-across the incoming surge, which has the effect of inverting the surge and reducing it to a benign level, due to the low impedance of the , capacitors, thus protecting the load 17.
Referring to Figure 2, a preferred embodiment wiring diagram is shown. Capacitor CI is inside tie diode bridge D3, D6, D7, D8. This capacitor will charge up to the peak ofthe power wave voltage; and maintain that voltage since RI discharges very little of the voltage during each power wave cycle. Any voltage (such as a surge voltage) which exceeds the peak of the normal power wave voltage appears across C1 to and is transferred to the high pass network consisting of C5, R10, R8, C6, R3. This two section high pass filter is selected to provide sufficient current to actiYvate the SCRs, SCRI and SCR2.
The SCRs in this example require up to 30 ma each to turn on.
Since there may be an unbalance in their characteristics, series resistors R4 and R5 are used to assure balanced current drive to the SCRs.
Assuming a 3 to 1 overdrive current (180 ma. total), and driving from a . _17_ low enough impedance to assure adequate drive current for faster turn-on, R10 may be established at about 200 Ohms for a surge inversion voltage of 100 Volts for a worst case 6,000 Volt surge. The values for each of the components shown in. Figure 2 are as follows:
PART NO. DESCRIPTIdN AND VALUE
Capacitors C1 120 mfd, 450 volt C2 120 mfd, 450 volt C3 120 mfd, 450 volt .
C4 1 mfd, 250 volt C5 ~ 0.1 mfd, 400 volt C6 0.22 mfd, 50 volt Diodes Dl LED
D2 3 amp, 400 volt rectifier diode D3 6 amp, 800 volt rectifier diode D4 15 volt, 1 watt Zener diode DS 1 amp, 400 volt rectifier diode D6 6 amp, 800 volt rectifier diode D7 6 amp, 800 volt rectifier diode D8 6 amp, 800 volt rectifier diode Inductors L1 2.2 microhenry L2 2:2 microhenry L3 100 microhenry Resistors Rl 68k; 2 watt R2 . 390 ohm, 5 watt R3 47 ohm R4 47 ohm 1 s RS 47 ohm R6 390 ohm, 5 watt R7 5 ohm, 5 watt R8 47 ohm R9 2.7k R10 180 ohm, 1 watt S SCRs ' SCRI 20 amp, 600 volt SCR2 20 amp, 600 volt Utilizing the present invention device illustrated in Figure 2 above, tests were made over a range of voltages with a SOOamp surge to show the efFcacy of the present invention for varied voltages: Figures 3, 4 and 5 show the results.
in Figures 3, 4 and 5, respectively, waveforms are shown for 85 Volts RMS, 120 Volts RMS, and 240 Yolts RMS, for a 6 kV, 500 amp surge. In each of these Figures, the applied surge voltage and the let-through voltage are plotted against time. In Figure 3, the peak let-through voltage was about 0.25 kV, for Figure 4, about 0.29 kV and for Figure 5, about 0.46 kV, showing the consistent present invention surge suppression performance independent of the wide input voltage range. It can be seen that, while the incoming surge voltage exceeds the peak of the power wave for a period greater than 100 microseconds, the iet-through voltage of this invention exceeds the peak voltage ofthe power wave for less than 6 microseconds in every case from $5 VAC to 240 VAC, thereby greatly diminishing the surge energy transferred to the to protected load.
The essence of the present invention is the use of a L-C low pass input filter to act as an energy integrator and surge current Iirmiter followed by a two section R-C filter. The two section high pass filter selects out surge energy levels large enough to do damage; while ignoring normal power line voltage conditions. When the surge energy levels are high enough, a semiconductor switching circuit is enabled to effectively invert surge energy before it can do any harm. Passive and active components are used which all operate within their transient ratings, so no degradation takes place during a surge, and the circuit has no inherent failure mode (non-sacrificial.
This circuit is an improvement over prior art in that it eliminates controlling Zener diodes and, thus, eliminates circuitry that limited the voltage range of optimum protection. The improved circuit of the present invention device functions optimally and essentially independently of the supply voltage, giving it superior performance independent of brownouts and enabling optimum protection for wide input voltage range equipment using switch-mode power supplies.
Obviously, numerous modifications and variations of the present invention are possible in light of the above teachings. It is therefore understood that within the scope of the appended claims, the invention i5 may be practiced otherwise than as specifically described herein, for example, the present invention suppressor could' be employed in three phase applications.
Claims (20)
1. A wide input voltage range surge suppressor, which comprises:
a series circuit means, including, in series for attachment to an upstream AC power input, and to a downstream load:
(a) a nonlinear low pass L-C filter having an inductor and a diode bridge, wherein said diode bridge includes at least one capacitor;
(b) a two section high pass filter connected to said at least one capacitor;
(c) at least one electronic switch connected to said two section high pass filter; and, (d) at least one capacitor connected to said electronic switch.
a series circuit means, including, in series for attachment to an upstream AC power input, and to a downstream load:
(a) a nonlinear low pass L-C filter having an inductor and a diode bridge, wherein said diode bridge includes at least one capacitor;
(b) a two section high pass filter connected to said at least one capacitor;
(c) at least one electronic switch connected to said two section high pass filter; and, (d) at least one capacitor connected to said electronic switch.
2. The wide input voltage range surge suppressor of claim 1 which further includes:
(e) a voltage offset diode connected to said two section high pass filter.
(e) a voltage offset diode connected to said two section high pass filter.
3. The wide input voltage range surge suppressor of claim 1 wherein said at least one capacitor connected to said electronic switch is said at least one capacitor of said nonlinear low pass L-C filter diode bridge.
4. The wide input voltage range surge suppressor of claim 1 wherein said electronic switch includes at least one series resistor for current drive balance assurance.
5. The wide input voltage range surge suppressor of claim 1 wherein said nonlinear low pass L-C filter diode bridge includes at least two electrolytic capacitors.
6. The wide input voltage range surge suppressor of claim 1 wherein said electronic switch is a silicon controlled rectifier switch.
7. The wide input voltage range surge suppressor of claim 1 wherein said at least one capacitor of said nonlinear low pass L-C
filter diode bridge has a rating within the range of about 50 microfarads to about 400 microfarads.
filter diode bridge has a rating within the range of about 50 microfarads to about 400 microfarads.
8. The wide input voltage range surge suppressor of claim 1 said low pass L-C filter diode bridge has rectifier diodes in the range of about 3 amps, 400 volts to about 6 amps, 800 volts.
9. The wide input voltage range surge suppressor of claim 1 wherein said two section high pass filter includes at least one capacitor having a rating within the range of about 0.05 microfarads to about 0.5 microfarads, and at least a second capacitor, said second capacitor having a rating within the range of about 0.1microfarads to about 1.0 microfarads.
10. The wide input voltage range surge suppressor of claim 9 wherein said two section high pass filter includes a resistor having a rating within the range of about 100 ohms to about 400 ohms, and at least a second resistor, said second resistor having a rating within the range of about 20 ohms to about 200 ohms.
11. The wide input voltage range surge suppressor of claim 9 wherein said at least one capacitor connected to said electronic switch is separate from said at least one capacitor of said nonlinear low pass L-C filter diode bridge and is contained within a separate bridge.
12. A wide input voltage range surge suppressor, which comprises:
a series circuit means, including, in series for attachment to an upstream AC power input, and to a downstream load:
(a) a nonlinear low pass L-C filter having a low Q linear inductor and a diode bridge, wherein said diode bridge includes at least one electrolytic capacitor, said filter adapted for attachment to an AC
power input;
(b) a two section high pass filter connected to said at least one electrolytic capacitor, said filter having at least two diversely rated capacitors and at least three diversely rated resistors;
(c) a voltage offset diode connected to said two section high pass filter;
(d) at least one electronic switch connected to said voltage offset diode;
and, (e) at least one capacitor connected to said electronic switch.
a series circuit means, including, in series for attachment to an upstream AC power input, and to a downstream load:
(a) a nonlinear low pass L-C filter having a low Q linear inductor and a diode bridge, wherein said diode bridge includes at least one electrolytic capacitor, said filter adapted for attachment to an AC
power input;
(b) a two section high pass filter connected to said at least one electrolytic capacitor, said filter having at least two diversely rated capacitors and at least three diversely rated resistors;
(c) a voltage offset diode connected to said two section high pass filter;
(d) at least one electronic switch connected to said voltage offset diode;
and, (e) at least one capacitor connected to said electronic switch.
13. The wide input voltage range surge suppressor of claim 12 wherein said at least one capacitor connected to said electronic switch is said at least one capacitor of said nonlinear low pass L-C filter diode bridge.
14. The wide input voltage range surge suppressor of claim 12 wherein said electronic switch includes at least one series resistor for current drive balance assurance.
15. The wide input voltage range surge suppressor of claim 12 wherein said nonlinear low pass L-C filter diode bridge includes at least two electrolytic capacitors.
16. The wide input voltage range surge suppressor of claim 12 wherein said electronic switch is a silicon controlled rectifier switch.
17. The wide input voltage range surge suppressor of claim 12 wherein said at least one electrolytic capacitor of said nonlinear low pass L-C
filter diode bridge has a rating within the range of about 50 microfarads to about 400 microfarads.
filter diode bridge has a rating within the range of about 50 microfarads to about 400 microfarads.
18. The wide input voltage range surge suppressor of claim 12 said low pass L-C filter diode bridge has rectifier diodes in the range of about 3 amps, 400 volts to about 6 amps, 800 volts.
19. The wide input voltage range surge suppressor of claim 12 wherein said two section high pass filter includes at least one capacitor having a rating within the range of about 0.05 microfarads to about 0.5 microfarads, and at least a second capacitor, said second capacitor having a rating within the range of about 0.1 microfarads to about 1.0 microfarads.
20. The wide input voltage range surge suppressor of claim 19 wherein said two section high pass filter includes a resistor having a rating within the range of about 100 ohms to about 400 ohms, and at least a second resistor, said second resistor having a rating within the range of about 20 ohms to about 200 ohms, and at least a third resistor, said third resistor having a rating within the range of about 10 ohms to about 200 ohms.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA2461332A CA2461332C (en) | 2004-03-17 | 2004-03-17 | Wide input voltage range surge suppressor |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CA2461332A CA2461332C (en) | 2004-03-17 | 2004-03-17 | Wide input voltage range surge suppressor |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CA2461332A1 CA2461332A1 (en) | 2005-09-17 |
| CA2461332C true CA2461332C (en) | 2011-06-28 |
Family
ID=35005568
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA2461332A Expired - Lifetime CA2461332C (en) | 2004-03-17 | 2004-03-17 | Wide input voltage range surge suppressor |
Country Status (1)
| Country | Link |
|---|---|
| CA (1) | CA2461332C (en) |
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2004
- 2004-03-17 CA CA2461332A patent/CA2461332C/en not_active Expired - Lifetime
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| Publication number | Publication date |
|---|---|
| CA2461332A1 (en) | 2005-09-17 |
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