CN103490397B - A kind of current-output type Secure isolation grid - Google Patents
A kind of current-output type Secure isolation grid Download PDFInfo
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- CN103490397B CN103490397B CN201310476136.5A CN201310476136A CN103490397B CN 103490397 B CN103490397 B CN 103490397B CN 201310476136 A CN201310476136 A CN 201310476136A CN 103490397 B CN103490397 B CN 103490397B
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Abstract
The invention discloses a kind of current-output type Secure isolation grid, these current-output type Secure isolation grid comprise mutually isolated power supply area, place of safety and hazardous area, input and output, input is connected with control system, for obtaining current mode standard industrial process signals, and described current mode standard industrial process signals is inputed to described place of safety, power supply area is for generation of the insulating power supply in supply security district and hazardous area, isolated by isolating transformer between place of safety and hazardous area, output is connected with actuator, for output current is transferred to actuator.In current-output type Secure isolation grid disclosed by the invention, realized the connection in place of safety and hazardous area as isolating device by use isolating transformer, burn out detection and warning just can be realized in place of safety, need not form the signal coupling passage by way of place of safety and hazardous area, and then the energy that can reduce supply intrinsically safe circuit exceeds the risk of safe range.
Description
Technical field
The present invention relates to automation and instrument field, in particular, relate to a kind of current-output type Secure isolation grid.
Background technology
Secure isolation grid are that one is connected between intrinsically safe circuit and immaterial safety circuit, by the device of energy limited in certain safe range of supply intrinsically safe circuit.Wherein, intrinsically safe circuit connects hazardous area, and immaterial safety circuit connects place of safety.Control system is contained in immaterial safety circuit, and actuator is contained in intrinsically safe circuit.
Current-output type Secure isolation grid are the equipment that a kind of current mode standard industrial process signals (4 ~ 20mA) by control system passes to actuator (such as, valve).Its mainly according to power supply area, place of safety, hazardous area three separate from pattern design, wherein, place of safety connection control system forms input current loop, hazardous area connects actuator and forms output current loop, under normal condition, output current loop can copy the electric current of input current loop completely.
Hazardous area broken string is a kind of common fault, therefore, current-output type Secure isolation grid has burn out detection and warning function circuit.The mode of burn out detection and warning function electric circuit inspection hazardous area broken string has multiple, what generally adopt at present is by sampling to the current signal of output current loop, then passing to place of safety, when sample rate current is less than 4mA, control system is reported to the police after being changed by this current signal.
In aforesaid way, the information whether hazardous area breaks is passed to place of safety by burn out detection and warning function circuit, relate to the transmission of information between two isolated areas, in order to ensure that the energy supplying intrinsically safe circuit is in certain safe range, the related specifications requirement of burn out detection and warning function circuit demand fulfillment intrinsically safe circuit, in prior art, one method is, adopt common optical coupler as additional isolating device, and adopt the fusible link, current-limiting resistance, the zener composition energy limited unit that meet intrinsic safety requirements, the output energy of limiting circuit; Another kind method selects to meet the special optocoupler of intrinsic safety specification requirement as additional isolating device.
But, in above-mentioned two kinds of methods, all need to increase extra optocoupler as isolating device to realize the connection of place of safety and hazardous area, burn out detection and warning circuit is made to be independent signal transmission loops, this increases directly causing the coupling channel of place of safety and hazardous area, and the energy considerably increasing supply intrinsically safe circuit exceeds the risk of safe range.
Summary of the invention
In view of this, the invention provides a kind of current-output type Secure isolation grid, to overcome in prior art when carrying out hazardous area burn out detection, owing to needing to increase extra optocoupler as isolating device to realize the connection of place of safety and hazardous area, and then causing the coupling channel in place of safety and hazardous area to increase, the energy considerably increasing supply intrinsically safe circuit exceeds the problem of the risk of safe range.
For achieving the above object, the invention provides following technical scheme:
A kind of current-output type Secure isolation grid, comprising: power supply area, place of safety, hazardous area, input and output;
Described input is connected with control system, for obtaining current mode standard industrial process signals, and described current mode standard industrial process signals is inputed to described place of safety;
Described power supply area is for generation of the insulating power supply supplying described place of safety and described hazardous area;
Isolated by isolating transformer between described place of safety and described hazardous area;
Described output is connected with actuator, for the output current produced by isolating transformer coupling is transferred to described actuator.
Preferably, described place of safety comprises the primary side of burn out detection alarm unit and described isolating transformer;
Wherein, described current mode standard industrial process signals for receiving described current mode standard industrial process signals, and is exported to the primary side of described isolating transformer by described burn out detection alarm unit.
Preferably, described hazardous area comprises the secondary side of limit energy unit, current replication unit and described isolating transformer;
Wherein, described limit energy unit, for ensureing that the power supply being transferred to actuator is in predetermined safe range;
Described current replication unit, produces described output current for being coupled with the primary side of described isolating transformer by the secondary side of described isolating transformer.
Preferably, the primary side of described isolating transformer comprises: the first switch, the first winding, second switch, the second winding and the first electric capacity;
Wherein, the first end of described first switch is connected with the first end of described first winding;
Second end of described first winding is connected with the first end of described second winding;
Second end of described second winding is connected with the second end of described second switch;
The first end of described second switch is connected with the second end of described first switch;
Described first electric capacity first end is connected with the second end of described first switch;
Second end of described first electric capacity is connected with the second end of described first winding;
The current mode standard industrial process signals that described isolating transformer primary side receives is flowed into by the second end of described first winding.
Preferably, the secondary side of described isolating transformer comprises: the tertiary winding, the 3rd switch, the 4th winding, the 4th switch and the second electric capacity;
Wherein, the first end of the described tertiary winding is connected with the first end of described 3rd switch;
Second end of described 3rd switch is connected with the first end of described 4th switch;
Second end of described 4th switch is connected with the second end of described 4th winding;
The first end of described 4th winding is connected with the first end of the described tertiary winding;
The first end of described second electric capacity is connected with the second end of described 3rd switch and ground connection;
Second end of described second electric capacity is connected with the second end of the described tertiary winding;
The described output current that described isolating transformer secondary side produces is flowed out by the second end of the described tertiary winding.
Preferably, described burn out detection alarm unit comprises: the first comparator, the first switching tube and the first current-limiting resistance;
Wherein, the first end of described first comparator connects reference voltage, and the second end of described first comparator connects the second end of described first electric capacity, when the voltage of described first electric capacity is less than reference voltage, and the first switching tube conducting; When the voltage of described first electric capacity is greater than reference voltage, the first current-limiting resistance conducting, described burn out detection alarm unit is reported to the police.
Preferably, described first electric capacity and described second electric capacity are 0.1 microfarad.
Preferably, described current mode Secure isolation grid, also comprise:
The current mode standard industrial process signals that described isolation voltage device primary side receives is flowed into by the first end of described second winding.
Preferably, described current mode standard industrial process signals is the electric current of 4 ~ 20 milliamperes.
Known via above-mentioned technical scheme, compared with prior art, the invention discloses a kind of current-output type Secure isolation grid, these current-output type Secure isolation grid comprise mutually isolated power supply area, place of safety and hazardous area, input and output, described input is connected with control system, for obtaining current mode standard industrial process signals, and described current mode standard industrial process signals is inputed to described place of safety, described power supply area is for generation of the insulating power supply supplying described place of safety and described hazardous area, isolated by isolating transformer between described place of safety and described hazardous area, described output is connected with actuator, for output current is transferred to described actuator.In current-output type Secure isolation grid disclosed by the invention, realized the connection in place of safety and hazardous area as isolating device by use isolating transformer, burn out detection and warning just can be realized in place of safety, need not form the signal coupling passage by way of place of safety and hazardous area, and then the energy that can reduce supply intrinsically safe circuit exceeds the risk of safe range.
Accompanying drawing explanation
In order to be illustrated more clearly in the embodiment of the present invention or technical scheme of the prior art, be briefly described to the accompanying drawing used required in embodiment or description of the prior art below, apparently, accompanying drawing in the following describes is only embodiments of the invention, for those of ordinary skill in the art, under the prerequisite not paying creative work, other accompanying drawing can also be obtained according to the accompanying drawing provided.
Fig. 1 is a kind of current-output type Secure isolation grid concrete structure schematic diagram disclosed in the embodiment of the present invention one;
Fig. 2 is another kind of current-output type Secure isolation grid concrete structure schematic diagram disclosed in the embodiment of the present invention two;
Fig. 3 is the embodiment of the present invention three another current-output type Secure isolation grid concrete structure schematic diagram disclosed.
Embodiment
Below in conjunction with the accompanying drawing in the embodiment of the present invention, be clearly and completely described the technical scheme in the embodiment of the present invention, obviously, described embodiment is only the present invention's part embodiment, instead of whole embodiments.Based on the embodiment in the present invention, those of ordinary skill in the art, not making the every other embodiment obtained under creative work prerequisite, belong to the scope of protection of the invention.
From background technology, burn out detection in existing current-output type Secure isolation grid and warning function circuit all need to increase extra optocoupler as isolating device to realize the connection of place of safety and hazardous area, burn out detection and warning circuit is made to be independent signal transmission loops, this increases directly causing the coupling channel of place of safety and hazardous area, and the energy considerably increasing supply intrinsically safe circuit exceeds the risk of safe range.
Therefore, the invention discloses a kind of current-output type Secure isolation grid, these current-output type Secure isolation grid comprise mutually isolated power supply area, place of safety and hazardous area, input and output, described input is connected with control system, for obtaining current mode standard industrial process signals, and described current mode standard industrial process signals is inputed to described place of safety, described power supply area is for generation of the insulating power supply supplying described place of safety and described hazardous area, isolated by isolating transformer between described place of safety and described hazardous area, described output is connected with actuator, for output current is transferred to described actuator.In current-output type Secure isolation grid disclosed by the invention, realized the connection in place of safety and hazardous area as isolating device by use isolating transformer, burn out detection and warning just can be realized in place of safety, need not form the signal coupling passage by way of place of safety and hazardous area, and then the energy that can reduce supply intrinsically safe circuit exceeds the risk of safe range.
Have and will be described in detail by following examples about the concrete structure of these current-output type Secure isolation grid and functional realiey principle.
Embodiment one
Referring to accompanying drawing 1, is a kind of current-output type Secure isolation grid concrete structure schematic diagram disclosed by the invention.
These current-output type Secure isolation grid are made up of power supply area 10, place of safety 11, hazardous area 12, input 13 and output 14.Its annexation is specific as follows:
Described input 13 is connected with control system, for obtaining current mode standard industrial process signals, and described current mode standard industrial process signals is inputed to described place of safety 11.
It should be noted that, completely isolated on electrically between the power supply area 10 of the Secure isolation of current-output type disclosed in the present embodiment grid, place of safety 11 and hazardous area 12, input 13 is the current mode standard industrial process signals of 4 ~ 20mA from the control signal that control system (as DCS) obtains, this current mode standard industrial process signals directly enters the place of safety 11 of current-output type Secure isolation grid, the electric current that place of safety 11 exports can be copied in hazardous area 12, under normal circumstances, error generally can control to below one thousandth.
Described power supply area 10 is for generation of the insulating power supply supplying described place of safety 11 and described hazardous area 12.
Isolated by isolating transformer 15 between described place of safety 11 and described hazardous area 12.
Be connected by an isolating transformer 15 between place of safety 11 and hazardous area 12 in the present embodiment, the two is electrical isolation each other, based on the magnetic field delivered current signal that isolating transformer 15 produces.In time breaking in hazardous area, so hazardous area electric current is just always 0, and place of safety maintenance has electric current, there is difference between current in isolating transformer two ends, at this moment, the induced electromotive force at isolating transformer coil two ends will increase rapidly, therefore just can judge whether hazardous area there occurs broken string by the size detecting induced electromotive force from place of safety.
Described output 14 is connected with actuator, for the output current produced that is coupled by isolating transformer 15 is transferred to described actuator.
Present embodiment discloses a kind of current-output type Secure isolation grid, these current-output type Secure isolation grid comprise mutually isolated power supply area, place of safety and hazardous area, input and output, described input is connected with control system, for obtaining current mode standard industrial process signals, and described current mode standard industrial process signals is inputed to described place of safety, described power supply area is for generation of the insulating power supply supplying described place of safety and described hazardous area, isolated by isolating transformer between described place of safety and described hazardous area, described output is connected with actuator, for output current is transferred to described actuator.In current-output type Secure isolation grid disclosed in the present embodiment, realized the connection in place of safety and hazardous area as isolating device by use isolating transformer, burn out detection and warning just can be realized in place of safety, need not form the signal coupling passage by way of place of safety and hazardous area, and then the energy that can reduce supply intrinsically safe circuit exceeds the risk of safe range.
Above embodiment one only simply gives the module composition of a kind of current-output type Secure isolation grid disclosed in the present application, on the basis of above-described embodiment one, has the particular circuit configurations about modules, will be described in detail by following examples.
Embodiment two
Refer to accompanying drawing 2, be current-output type Secure isolation grid concrete structure schematic diagram another kind of disclosed in the embodiment of the present invention, these current-output type Secure isolation grid are specifically made up of power supply area 10, place of safety 11, hazardous area 12, input 13 and output 14.Wherein, place of safety 11 comprises the primary side of burn out detection alarm unit 110 and described isolating transformer 15; Hazardous area 12 comprises the secondary side of limit energy unit 120, current replication unit 121 and described isolating transformer 15;
Its annexation is specific as follows:
Described input 13 is connected with control system, for obtaining current mode standard industrial process signals, and described current mode standard industrial process signals is inputed to described place of safety 11.
It should be noted that, completely isolated on electrically between the power supply area 10 of the Secure isolation of current-output type disclosed in the present embodiment grid, place of safety 11 and hazardous area 12, input 13 is the current mode standard industrial process signals of 4 ~ 20mA from the control signal that control system (as DCS) obtains, this current mode standard industrial process signals directly enters the place of safety 11 of current-output type Secure isolation grid, the electric current that place of safety 11 exports can be copied in hazardous area 12, under normal circumstances, error generally can control to below one thousandth.
Described power supply area 10 is for generation of the insulating power supply supplying described place of safety 11 and described hazardous area 12.
Isolated by isolating transformer 15 between described place of safety 11 and described hazardous area 12.
Be connected by an isolating transformer 15 between place of safety 11 and hazardous area 12 in the present embodiment, the two is electrical isolation each other, based on the magnetic field delivered current signal that isolating transformer 15 produces.
Described current mode standard industrial process signals for receiving described current mode standard industrial process signals, and is exported to the primary side of described isolating transformer by described burn out detection alarm unit 110.
Burn out detection alarm unit 110 can detect the broken string state of the outlet line in hazardous area.The mode of reporting to the police can be varied, as logical signal warnings, indicator light warning etc., but generally can report to the police by the mode limiting place of safety electric current loop electric current and be less than 4mA, can save cable and facilitate control system (as DCS) to detect.In the present embodiment, burn out detection alarm unit is in conjunction with the feature of control system, take current-limiting circuit, the mode be limited in by input current beyond 4 ~ 20mA standard industry current range is reported to the police, when control system detects that place of safety electric current loop electric current is less than 4mA, can learn to break in hazardous area, now namely report to the police by various audible-visual annunciator.
The primary side of described isolating transformer 15 comprises: the first K switch 1, first winding T1, second switch K2, the second winding T2 and the first electric capacity C1;
Wherein, the first end of described first switch is connected with the first end of described first winding;
Second end of described first winding is connected with the first end of described second winding;
Second end of described second winding is connected with the second end of described second switch;
The first end of described second switch is connected with the second end of described first switch;
Described first electric capacity first end is connected with the second end of described first switch;
Second end of described first electric capacity is connected with the second end of described first winding;
The current mode standard industrial process signals that described isolating transformer primary side receives is flowed into by the second end of described first winding.
Described limit energy unit 120, for ensureing that the power supply being transferred to actuator is in predetermined safe range;
Described current replication unit 121, produces described output current for being coupled with the primary side of described isolating transformer by the secondary side of described isolating transformer.
It should be noted that, the concrete structure in hazardous area disclosed in the present embodiment is compared with hazardous area in prior art, simply increase the secondary side of isolating transformer, other structures do not change, therefore have physical circuit and correlation function about limitting energy unit 120 and current replication unit 121 no longer to describe in detail.
Concrete, the secondary side of described isolating transformer comprises: tertiary winding T3, the 3rd K switch 3, the 4th winding T4, the 4th K switch 4 and the second electric capacity C2;
Wherein, the first end of the described tertiary winding is connected with the first end of described 3rd switch;
Second end of described 3rd switch is connected with the first end of described 4th switch;
Second end of described 4th switch is connected with the second end of described 4th winding;
The first end of described 4th winding is connected with the first end of the described tertiary winding;
The first end of described second electric capacity is connected with the second end of described 3rd switch and ground connection;
Second end of described second electric capacity is connected with the second end of the described tertiary winding;
The described output current that described isolating transformer secondary side produces is flowed out by the second end of the described tertiary winding.
Described output 14 is connected with actuator, for the output current produced by isolating transformer coupling is transferred to described actuator.
In the present embodiment, four umber of turns of isolating transformer are completely the same, and coiling is carried out according to the Same Name of Ends mark of isolating transformer in accompanying drawing 2 in its direction, K1, K2 be the synchronous alternation switch with K3, K4 respectively, namely pre-sets the on off state of fixed frequency control K1, K2, K3, a K4, according to fixed frequency, cycle regular time can be drawn, at point sometime, K1 and K3 closes, K2 and K4 disconnects, after the above-mentioned time cycle, K1 and K3 disconnects, and meanwhile, K2 and K4 closes.The flow direction that place of safety input current (being called I1) and hazardous area output current (being called I2) can be made thus to produce in isolating transformer magnetic core is contrary all the time, if I1 size equals I2, so magnetic flux is offset completely, isolating transformer coil two ends do not have induced voltage to produce, if I1 differs in size in I2, then magnetic flux can not be offset completely, and remaining magnetic flux total amount is Φ=L(I1-I2); According to the law of electromagnetic induction, induced voltage ε=ΔΦ/Δ T=2L(I1-I2 that isolating transformer coil produces)/Δ T, also namely: the induced electromotive force at isolating transformer coil two ends and place of safety and hazardous area current differential are directly proportional.
In the present embodiment, the current-output type Secure isolation grid based on isolating transformer transmission of signal apply above-mentioned principle just, by the size of control ε, I1 and I2 are matched, and the less error then between I1 and I2 of ε is less.
In time breaking in hazardous area, so hazardous area electric current is just always 0, and place of safety maintenance has electric current, there is difference between current in isolating transformer coil both sides, at this moment the induced electromotive force ε at transformer coil two ends can increase rapidly, therefore can detect the size of induced electromotive force from place of safety to judge whether hazardous area there occurs broken string.
A kind of current-output type Secure isolation grid disclosed in the present embodiment, on the basis of current-output type Secure isolation grid disclosed in embodiment one, further describe circuit structure and the specific implementation principle of these current-output type Secure isolation grid.In current-output type Secure isolation grid disclosed in the present embodiment, realized the connection in place of safety and hazardous area as isolating device by use isolating transformer, burn out detection and warning just can be realized in place of safety, need not form the signal coupling passage by way of place of safety and hazardous area, and then the energy that can reduce supply intrinsically safe circuit exceeds the risk of safe range.
How detecting hazardous area broken string to further describe current-output type Secure isolation grid disclosed in above-described embodiment and report to the police, the application gives following examples and is described in detail.
Embodiment three
Refer to accompanying drawing 3, be another current-output type Secure isolation grid concrete structure schematic diagram disclosed in the embodiment of the present invention, these current-output type Secure isolation grid are specifically made up of power supply area 10, place of safety 11, hazardous area 12, input 13 and output 14.Wherein, place of safety 11 comprises the primary side of burn out detection alarm unit 110 and described isolating transformer 15; Hazardous area 12 comprises the secondary side of limit energy unit 120, current replication unit 121 and described isolating transformer 15;
Its annexation is specific as follows:
Described input 13 is connected with control system, for obtaining current mode standard industrial process signals, and described current mode standard industrial process signals is inputed to described place of safety 11.
It should be noted that, completely isolated on electrically between the power supply area 10 of the Secure isolation of current-output type disclosed in the present embodiment grid, place of safety 11 and hazardous area 12, input 13 is the current mode standard industrial process signals of 4 ~ 20mA from the control signal that control system (as DCS) obtains, this current mode standard industrial process signals directly enters the place of safety 11 of current-output type Secure isolation grid, the electric current that place of safety 11 exports can be copied in hazardous area 12, under normal circumstances, error generally can control to below one thousandth.
Described power supply area 10 is for generation of the insulating power supply supplying described place of safety 11 and described hazardous area 12.
Isolated by isolating transformer 15 between described place of safety 11 and described hazardous area 12.
Be connected by an isolating transformer 15 between place of safety 11 and hazardous area 12 in the present embodiment, the two is electrical isolation each other, based on the magnetic field delivered current signal that isolating transformer 15 produces.
Described current mode standard industrial process signals for receiving described current mode standard industrial process signals, and is exported to the primary side of described isolating transformer by described burn out detection alarm unit 110.
Burn out detection alarm unit 110 can detect the broken string state of the outlet line in hazardous area.The mode of reporting to the police can be varied, as logical signal warnings, indicator light warning etc., but generally can report to the police by the mode limiting place of safety electric current loop electric current and be less than 4mA, can save cable and facilitate control system (as DCS) to detect.In the present embodiment, burn out detection alarm unit is in conjunction with the feature of control system, take current-limiting circuit, the mode be limited in by input current beyond 4 ~ 20mA standard industry current range is reported to the police, when control system detects that place of safety electric current loop electric current is less than 4mA, can learn to break in hazardous area, now namely report to the police by various audible-visual annunciator.
Concrete, in the present embodiment, burn out detection alarm unit 110 comprises: the first comparator U1, the first switching tube Q5 and the first current-limiting resistance R1;
Wherein, the first end of described first comparator connects reference voltage V ref, and the second end of described first comparator connects the second end of described first electric capacity, when the voltage of described first electric capacity is less than reference voltage V ref, and the first switching tube conducting; When the voltage of described first electric capacity is greater than reference voltage V ref, the first current-limiting resistance conducting, described burn out detection alarm unit is reported to the police.
The primary side of described isolating transformer 15 comprises: the first K switch 1, first winding T1, second switch K2, the second winding T2 and the first electric capacity C1; The value of described first electric capacity C1 can be 0.1 microfarad, also the electric capacity of other sizes can be selected as the first electric capacity C1 according to actual conditions.
Wherein, the first end of described first switch is connected with the first end of described first winding;
Second end of described first winding is connected with the first end of described second winding;
Second end of described second winding is connected with the second end of described second switch;
The first end of described second switch is connected with the second end of described first switch;
Described first electric capacity first end is connected with the second end of described first switch;
Second end of described first electric capacity is connected with the second end of described first winding;
The current mode standard industrial process signals that described isolating transformer primary side receives is flowed into by the second end of described first winding.
Described limit energy unit 120, for ensureing that the power supply being transferred to actuator is in predetermined safe range;
Described current replication unit 121, produces described output current for being coupled with the primary side of described isolating transformer by the secondary side of described isolating transformer.
It should be noted that, the concrete structure in hazardous area disclosed in the present embodiment is compared with hazardous area in prior art, simply increase the secondary side of isolating transformer, other structures do not change, therefore have physical circuit and correlation function about limitting energy unit 120 and current replication unit 121 no longer to describe in detail.
Concrete, the secondary side of described isolating transformer comprises: tertiary winding T3, the 3rd K switch 3, the 4th winding T4, the 4th K switch 4 and the second electric capacity C2; The value of described second electric capacity C2 can be 0.1 microfarad, also the electric capacity of other sizes can be selected as the second electric capacity C2 according to actual conditions.
Wherein, the first end of the described tertiary winding is connected with the first end of described 3rd switch;
Second end of described 3rd switch is connected with the first end of described 4th switch;
Second end of described 4th switch is connected with the second end of described 4th winding;
The first end of described 4th winding is connected with the first end of the described tertiary winding;
The first end of described second electric capacity is connected with the second end of described 3rd switch and ground connection;
Second end of described second electric capacity is connected with the second end of the described tertiary winding;
The described output current that described isolating transformer secondary side produces is flowed out by the second end of the described tertiary winding.
Described output 14 is connected with actuator, for the output current produced by isolating transformer coupling is transferred to described actuator.
In the present embodiment, four umber of turns of isolating transformer are completely the same, and coiling is carried out according to the Same Name of Ends mark of isolating transformer in accompanying drawing 2 in its direction, K1, K2 be the synchronous alternation switch with K3, K4 respectively, namely pre-sets the on off state of fixed frequency control K1, K2, K3, a K4, according to fixed frequency, cycle regular time can be drawn, at point sometime, K1 and K3 closes, K2 and K4 disconnects, after the above-mentioned time cycle, K1 and K3 disconnects, and meanwhile, K2 and K4 closes.The flow direction that place of safety input current (being called I1) and hazardous area output current (being called I2) can be made thus to produce in isolating transformer magnetic core is contrary all the time, if I1 size equals I2, so magnetic flux is offset completely, isolating transformer coil two ends do not have induced voltage to produce, if I1 differs in size in I2, then magnetic flux can not be offset completely, and remaining magnetic flux total amount is Φ=L(I1-I2); According to the law of electromagnetic induction, induced voltage ε=ΔΦ/Δ T=2L(I1-I2 that isolating transformer coil produces)/Δ T, also namely: the induced electromotive force at isolating transformer coil two ends and place of safety and hazardous area current differential are directly proportional.
In the present embodiment, the current-output type Secure isolation grid based on isolating transformer transmission of signal apply above-mentioned principle just, by the size of control ε, I1 and I2 are matched, and the less error then between I1 and I2 of ε is less.
In time breaking in hazardous area, so hazardous area electric current is just always 0, and place of safety maintenance has electric current, there is difference between current in isolating transformer coil both sides, at this moment the induced electromotive force ε at transformer coil two ends can increase rapidly, therefore can detect the size of induced electromotive force from place of safety to judge whether hazardous area there occurs broken string.
Concrete, when current-output type Secure isolation grid normally work time, the output current I2 equal and opposite in direction in place of safety input current I1 and hazardous area, the induced electromotive force ε ≈ 0 of isolating transformer winding, namely the voltage at C1 two ends is about 0; And when the broken string of hazardous area, the induced electromotive force ε of isolating transformer winding is a larger value.
Sample to this voltage with U1, compare with a reference voltage V ref, the result compared is for the current-limiting circuit of control inputs electric current loop, and concrete control procedure is as follows:
Normal operation, induced voltage is far smaller than Vref, U1 output HIGH voltage, and driving switch pipe Q5 is completely open-minded.In time breaking in hazardous area, induced voltage is far longer than Vref, U1 output LOW voltage, driving switch pipe Q5 turns off completely, and now electric current only can flow into isolating transformer from R1, is generally 24V to the maximum according to control system (as DCS) output voltage, suitable resistance R1 can be designed, the electric current that order now flows into from R1 is less than 4mA(4mA electric current not within standard industry electric current 4 ~ 20mA scope), both can realize warning function, the reliably working of break detection circuit can be supported again.
It should be noted that, Vref is a default magnitude of voltage, this magnitude of voltage should be greater than the induced voltage of normal operation transformer, and the induced voltage be less than in broken string situation, usually all will carry out certain volume that rises or design of Reducing Rating to meet the needs of reliability service, in addition, namely Vref can be a fixing value, also can be the value of a change, namely can participate in loop and control.
It should be noted that further, the current mode standard industrial process signals that described isolation voltage device primary side receives is flowed into by the first end of described second winding.That is, the direction of isolating transformer four windings is except carrying out except coiling according to the Same Name of Ends mark in accompanying drawing 2, can also the direction that first side winding Same Name of Ends identifies be set to identical with the direction that secondary side winding Same Name of Ends identify, now, to put K1 and K4 sometime closed, K2 and K3 disconnects, at certain hour week after date, K1 and K4 disconnects, K2 and K3 closes, subsequent detection hazardous area broken string principle to describe before similar, repeat no more herein.
A kind of current-output type Secure isolation grid disclosed in the present embodiment, on the basis of current-output type Secure isolation grid disclosed in embodiment two, further describe the detection how being carried out hazardous area broken string by the burn out detection and alarm unit being placed in place of safety of these current-output type Secure isolation grid.In current-output type Secure isolation grid disclosed in the present embodiment, realized the connection in place of safety and hazardous area as isolating device by use isolating transformer, burn out detection and warning just can be realized in place of safety, need not form the signal coupling passage by way of place of safety and hazardous area, and then the energy that can reduce supply intrinsically safe circuit exceeds the risk of safe range.
In sum:
The invention discloses a kind of current-output type Secure isolation grid, these current-output type Secure isolation grid comprise mutually isolated power supply area, place of safety and hazardous area, input and output, described input is connected with control system, for obtaining current mode standard industrial process signals, and described current mode standard industrial process signals is inputed to described place of safety, described power supply area is for generation of the insulating power supply supplying described place of safety and described hazardous area, isolated by isolating transformer between described place of safety and described hazardous area, described output is connected with actuator, for output current is transferred to described actuator.In current-output type Secure isolation grid disclosed by the invention, realized the connection in place of safety and hazardous area as isolating device by use isolating transformer, burn out detection and warning just can be realized in place of safety, need not form the signal coupling passage by way of place of safety and hazardous area, and then the energy that can reduce supply intrinsically safe circuit exceeds the risk of safe range.
In this specification, each embodiment adopts the mode of going forward one by one to describe, and what each embodiment stressed is the difference with other embodiments, between each embodiment identical similar portion mutually see.For device disclosed in embodiment, because it corresponds to the method disclosed in Example, so description is fairly simple, relevant part illustrates see method part.
The software module that the method described in conjunction with embodiment disclosed herein or the step of algorithm can directly use hardware, processor to perform, or the combination of the two is implemented.Software module can be placed in the storage medium of other form any known in random asccess memory (RAM), internal memory, read-only memory (ROM), electrically programmable ROM, electrically erasable ROM, register, hard disk, moveable magnetic disc, CD-ROM or technical field.
To the above-mentioned explanation of the disclosed embodiments, professional and technical personnel in the field are realized or uses the present invention.To be apparent for those skilled in the art to the multiple amendment of these embodiments, General Principle as defined herein can without departing from the spirit or scope of the present invention, realize in other embodiments.Therefore, the present invention can not be restricted to these embodiments shown in this article, but will meet the widest scope consistent with principle disclosed herein and features of novelty.
Claims (8)
1. current-output type Secure isolation grid, is characterized in that, comprising: power supply area, place of safety, hazardous area, input and output;
Described input is connected with control system, for obtaining current mode standard industrial process signals, and described current mode standard industrial process signals is inputed to described place of safety;
Described power supply area is for generation of the insulating power supply supplying described place of safety and described hazardous area;
Isolated by isolating transformer between described place of safety and described hazardous area;
Described output is connected with actuator, for the output current produced by isolating transformer coupling is transferred to described actuator;
Wherein, described place of safety comprises the primary side of burn out detection alarm unit and described isolating transformer;
Wherein, described current mode standard industrial process signals for receiving described current mode standard industrial process signals, and is exported to the primary side of described isolating transformer by described burn out detection alarm unit.
2. current-output type Secure isolation grid according to claim 1, is characterized in that, described hazardous area comprises the secondary side of limit energy unit, current replication unit and described isolating transformer;
Wherein, described limit energy unit, for ensureing that the power supply being transferred to actuator is in predetermined safe range;
Described current replication unit, produces described output current for being coupled with the primary side of described isolating transformer by the secondary side of described isolating transformer.
3. current-output type Secure isolation grid according to claim 1, it is characterized in that, the primary side of described isolating transformer comprises: the first switch, the first winding, second switch, the second winding and the first electric capacity;
Wherein, the first end of described first switch is connected with the first end of described first winding;
Second end of described first winding is connected with the first end of described second winding;
Second end of described second winding is connected with the second end of described second switch;
The first end of described second switch is connected with the second end of described first switch;
Described first electric capacity first end is connected with the second end of described first switch;
Second end of described first electric capacity is connected with the second end of described first winding;
The current mode standard industrial process signals that described isolating transformer primary side receives is flowed into by the second end of described first winding.
4. current-output type Secure isolation grid according to claim 3, it is characterized in that, the secondary side of described isolating transformer comprises: the tertiary winding, the 3rd switch, the 4th winding, the 4th switch and the second electric capacity;
Wherein, the first end of the described tertiary winding is connected with the first end of described 3rd switch;
Second end of described 3rd switch is connected with the first end of described 4th switch;
Second end of described 4th switch is connected with the second end of described 4th winding;
The first end of described 4th winding is connected with the first end of the described tertiary winding;
The first end of described second electric capacity is connected with the second end of described 3rd switch and ground connection;
Second end of described second electric capacity is connected with the second end of the described tertiary winding;
The described output current that described isolating transformer secondary side produces is flowed out by the second end of the described tertiary winding.
5. current-output type Secure isolation grid according to claim 3, is characterized in that, described burn out detection alarm unit comprises: the first comparator, the first switching tube and the first current-limiting resistance;
Wherein, the first end of described first comparator connects reference voltage, and the second end of described first comparator connects the second end of described first electric capacity, when the voltage of described first electric capacity is less than reference voltage, and the first switching tube conducting; When the voltage of described first electric capacity is greater than reference voltage, the first current-limiting resistance conducting, described burn out detection alarm unit is reported to the police.
6. current-output type Secure isolation grid according to claim 4, is characterized in that, described first electric capacity and described second electric capacity are 0.1 microfarad.
7. current-output type Secure isolation grid according to claim 3, is characterized in that, also comprise:
The current mode standard industrial process signals that described isolating transformer primary side receives is flowed into by the first end of described second winding.
8. the current-output type Secure isolation grid according to claim 1 ~ 7 any one, is characterized in that, described current mode standard industrial process signals is the electric current of 4 ~ 20 milliamperes.
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| CN106300634B (en) * | 2016-08-17 | 2018-08-07 | 华康泰克信息技术（北京）有限公司 | A kind of uninterruptible power supply isolated gate device |
| CN112444719B (en) * | 2019-08-30 | 2025-01-10 | 上海辰竹仪表有限公司 | Hardware diagnostic circuits for intelligent functional safety barriers, safety barriers |
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