Feedback circuit of integrated current supply and current limiting component

FIELD: power units designed to ensure spark safety of loads.

SUBSTANCE: proposed device 200 designed to supply with power spark-proof load provided with feedback circuit of integrated current supply and current limiting component and also to minimize voltage that should be limited in compliance with sparking safety standards has power supply PS and output terminals T1-T2 for connecting device to spark-proof load. Voltage limiting unit Z1 inserted between power supply PS and output terminals T1-T2 is used to limit voltage across load leads. Current limiting unit 202 has barrier resistors designed for current-to-voltage conversion to provide for comparison by operational amplifier that controls variable impedance Q1 and limits current supply to load.

EFFECT: reduced manufacturing cost, improved sparking safety.

19 cl, 3 dwg

 

The present invention relates to a power supply for intrinsically safe load. More specifically, the invention relates to a device limiting the current supplied to the load, to meet the standards for intrinsic safety.

Electronic devices are often used in hazardous environments containing volatile materials. Problems often arise from the fact that spark or heat from electronic devices could cause ignition of volatile material. Thus, manufacturers of electronic devices for use in these hazardous environments should provide some protection for electronic devices that are not flammable volatile material.

One form of such protection is the provision of an intrinsically safe device.

Standards for intrinsic safety establish regulatory bodies, such as UL in the United States, CENELEC in Europe, CSA in Canada and TIIS in Japan. To ensure that the device meets the standards intrinsic safety, current, power and voltage in the device is limited to levels that prevent ignition of volatile material from sparks or heat generated by the device.

The problem is the power supply in an intrinsically safe device. Power, voltage and current of electricity is limited to levels insufficient to cause ignition of years is what material. Thus, in the power supply of the necessary elements to limit the power, voltage and current in an intrinsically safe device.

In a traditional power supply voltage limit by connecting one or more semiconductor Zener diodes between the power lines connecting the power supply output terminals. Semiconductor Zener diodes limit the voltage to the level of V. Limitation of the current provide by connecting a resistor having a resistance R, in series with the output terminal of the high voltage. The resistor limits the current to the level of V/R. the Power to regulate by limiting the voltage and current.

Limiting components, that is, diodes and resistors must be protected to prevent exceeding the elements of passport in case of damage. Typically the device includes a fuse to limit the current that can be supplied to the elements. The pick guard so that his passport specifications provided does not exceed the characteristics of the scattering power.

Although this is not required under the standards for intrinsic safety, the circuit power supply often add block limits current to prevent a blown fuse. There are many topologists is a mini-circuits limit the current, which can be used as the high-voltage side and low voltage side of the power supply. Most of topological schemes limitations of current includes a resistor for converting the current into a voltage for obtaining a feedback signal that is proportional to amperage. When this is compared with the reference voltage. In the result of the comparison, adjusts the impedance element connected in series. The problem with adding block limit current, is that the conversion of current to voltage increases total output resistance and causes an additional voltage drop below the level required to meet the standards for intrinsic safety.

The above and other problems are being addressed and progress has been made in the art by providing a power supply with feedback integrated current source and the element limiting current corresponding to the present invention. One advantage of feedback integrated current source and element limits current is that the voltage drop can be reduced to the minimum voltage that must be limited to meet the standards for intrinsic safety. The second advantage is that the number of the element is in circuit power supply is excluded, that reduces the production cost of the power supply.

In accordance with the present invention the function of the resistor to convert the current block power limit combined with the barrier function of the output resistance. It provides the output resistance less than the resistance required to prevent ignition of hazardous material. The combination of features provided by the moving parts of the unit limits the current location after the barrier resistance. In particular, the device changes the impedance moved to a location after the barrier resistance. One example of a device changes the impedance is a MOS transistor.

When the MOS transistor moved, there are two new lines to the output terminals. The first is the control output of the operational amplifier and the feedback from the barrier resistance. The input of the operational amplifier and the gate for the MOS transistor have a high impedance, and in each of these lines is placed a relatively high resistance resistors in comparison with barrier resistor. Total barrier resistance is the combination of the resistor placed in line with the inputs of the gate of the MOS transistor and the input of the operational amplifier. This limits the output resistance from the power supply to the level which is negligibly lower than one barrier resistance.

Aspect of the invention is an intrinsically safe device, configured to supply power to a load connected to the first output terminal and second output terminal, where the device includes:

power supply;

voltage limiter connected in parallel with the power source to limit the magnitude of the voltage generated by the power source;

the connection between the first side of the limiter voltage and the first output terminal;

a current limiter connected between the second side of the limiter voltage and the second output terminal, and a current limiter includes:

barrier resistor;

AC impedance;

comparator;

while the current limiter further comprises:

barrier resistor;

a variable impedance connected between the second output terminal and the first side of the barrier resistor;

the second side of the barrier resistor connected from the second side of the voltage limiter;

the reference resistance is connected to the input of the comparator;

the output of the comparator is connected with the control input of the variable impedance;

the signal generated by the comparator output to the input of the variable impedance controls the magnitude of the impedance of the specified variable is about impedance;

the connection between the first side barrier resistor and a comparator input for receiving a voltage representing the current in the barrier resistor;

the comparator compares a value of the reference voltage and the voltage taken from the barrier resistor, to limit to the maximum level of the current value of a current supplied to the load through the output terminals.

Preferably, intrinsically safe device further comprises a fuse connected between the positive side voltage of the power source and the circuit voltage limitation.

Preferably, the voltage limiter includes a diode having a cathode connected to the positive side of the power source, and the anode connected to the negative side of the power source.

Preferably, the voltage limiter includes a semiconductor Zener diode.

Preferably, the variable impedance includes a transistor connected between the first side barrier resistor and the second output terminal, for controlling the amount of current supplied to the load;

the comparator is an operational amplifier (OA), which controls the impedance of the transistor;

the comparator has an output connected with the control input of the transistor;

the comparator has a first input connected to the voltage p is Estalagem the magnitude of the load current, and also has a second input connected to the reference voltage; and

the voltage divider comprising the barrier resistor to form a voltage representing the load current, and a voltage divider connected to the first input of the operational amplifier and the negative side of the power source.

Preferably, the current limiter also includes a resistor connected between the output of the operational amplifier and control input of the transistor.

Preferably, the transistor includes a field effect transistor based on the structure type metal-oxide-semiconductor (MOS transistor).

Preferably, the voltage divider includes:

a first resistor connected between the first input of the operational amplifier and the drain of the transistor; and

barrier resistor having a first end connected to the specified flow, and a second end connected to the negative side of the power source.

Preferably, intrinsically safe device is characterized in that the load contains an electronic unit of a Coriolis flowmeter having a unit signal for forming the excitation signal and for receiving sensor signals and the power signal is connected to the first and second output terminals of the intrinsically safe device.

Preferably, the conversion unit signals with the contains:

the AC excitation signal excitation, and block the excitation is connected with the first and second output terminals of the intrinsically safe device; and

a conversion unit for receiving the sensor signals, and the conversion unit has an input connected to the output of the excitation.

Another aspect of the invention is a method of operation of an intrinsically safe device for supplying power to the load through the first and second output terminals, while this method contains the following steps:

connection voltage suppressor in parallel with the power source to limit the magnitude of the voltage generated by the power source;

the connection between the first side of the limiter voltage and the first output terminal;

and the method includes the additional steps:

connecting the first side of the barrier resistor in series with a variable impedance to the second output terminal;

the connection of the second side of the limiter voltage from the second side of the barrier resistor;

the implementation of the operation of the comparator for comparing the reference voltage with the voltage at the ends of the barrier resistor representing the current supplied to the load through the output terminals;

providing a control signal from the specified output is a of the comparator at the input of the variable impedance;

the operation of the variable impedance in response to receiving the control signal, to limit the maximum current passing through the barrier resistor and a variable impedance to the load.

Preferably, the step of limiting the voltage level includes the operation of a functioning diode for voltage limitation.

Preferably, the operation of the functioning of the diode includes a phase of operation of the semiconductor Zener.

Preferably, the method further includes the following steps:

intrinsically safe power from the terminals in the block excitation Coriolis flowmeter, and

the formation of the excitation signal block excitation, in response to reception of the specified capacity.

Preferably, the method additionally includes the stage of submission of the sensor signals to the conversion unit Coriolis flowmeter, in response to reception of the specified capacity.

Preferably, the step of limiting the maximum current delivered to a load, includes the following operations:

the operation of the voltage divider to generate a voltage that represents the current supplied to the load through the barrier resistor;

the operation of the operational amplifier for comparing the reference voltage with a voltage representing the current supplied to the load; and

provided the e signal from the output of the operational amplifier to the control input of the transistor, defining a variable impedance to limit the current supplied to the load.

Preferably, the phase of operation of the transistor includes a stage MOSFET.

Another aspect of the invention provides an intrinsically safe device, configured to supply power to a load connected to the first output terminal and second output terminal, and the specified device contains:

power supply;

voltage limiter connected in parallel with the power source, to limit the maximum voltage generated by the power source;

the connection between the first side of the limiter voltage and the first output terminal; and

when the specified device contains:

a current limiter connected between the second side of the limiter voltage and the second output terminal;

the limiter current, containing:

the reference voltage,

AC impedance,

barrier resistor, and

the second side of the voltage limiter connected in series with the barrier resistor and a variable impedance to the second output terminal,

the current limiter limits the current supplied to the load through these output terminals, up to the maximum level of current, by comparing the reference voltage with the voltage at the end of the barrier resistor.

Another aspect of the invention provides a method for operation of an intrinsically safe device for supplying power to the load, and this method contains the following steps:

connection voltage suppressor in parallel with the power source to limit the maximum voltage generated by the power source;

providing connection between the first side of the limiter voltage and the first output terminal;

connecting the second side of the voltage limiter in series with the barrier resistor and a variable impedance to the second output terminal; and

limiting the current supplied to the load through the output terminals, up to the maximum level of current depending on the comparison of the reference voltage with the voltage at the ends of the barrier resistor representing the current supplied to the load through the barrier resistor and output terminals.

Brief description of drawings

The above and other characteristics relevant to the present invention, can be understood when reading the detailed description and the following drawings, in which:

figure 1 represents the power supply of the prior art for intrinsically safe load;

figure 2 represents a power supply for intrinsically safe load according to the present invention; and

figure 3 depicts spending the Omer Coriolis, in measuring electronic unit that includes the power supply unit corresponding to the present invention.

Detailed description of the invention

The power supply corresponding to the present invention, provides the total output resistance, which is no more required to prevent ignition of volatile material in a hazardous environment. Figure 1 shows a typical block 100 power to illustrate the differences between the power supply corresponding to the present invention, and conventional intrinsically safe power supply unit.

Intrinsically safe unit 100 power supply of the prior art delivers sufficient power to the load for restrictions in the most adverse conditions supply voltage, current and power to levels insufficient to cause ignition of hazardous material. Block 101 limits voltage limits the voltage at the ends of the load. In block 100, the power supply unit 101 limit voltage is a semiconductor Zener diode Z1 connected between lines 110 and 120. Specialist in the art will understand that between lines 110 and 120 can be connected to more than one semiconductor Zener diode for voltage limitation. For this description, it is possible that the block 101 limits voltage limits the voltage at the ends of the load (not the azan) to level V Z.

Block 102 limits the instantaneous current limit instantaneous current supplied to the load. In block 100, the power supply unit limits the instantaneous current includes a resistor Rb, which is connected in series with the output terminals T1 and T2. In this embodiment, the resistor Rbconnected between the positive output terminal T1 and the source PS of the power line 110. This helps limit the instantaneous current to Vz/Rbwhere Rbis the resistance of resistor Rb. The power delivered to a load (not shown), bounded by the limits of voltage and current.

Between the source PS of power and a positive output terminal T1 is connected to the F1 fuse to protect unit 101 voltage limitation unit 102 limits the instantaneous current in the event of damage to the device. Fuse F1 prevents excess unit 101 limit voltage and the block 102 limits the instantaneous current passport characteristics of these elements.

Block 103 limits the average current prevents the blown fuse F1 in case of short circuit output terminals T1 and T2. There are many well-known topological schemes that can be used to obtain unit 103 limits the average current. In block 100 the power unit limit average current consists of the following elements. The source of TRANS who Stora Q1 is connected to the negative output terminal T2. The source of transistor Q1 is connected to the resistor Rv. The resistor Rvconverts the pass-through current in voltage to obtain a voltage feedback which is proportional passing current. The output of the operational amplifier OA is connected to the gate of the transistor Q1, and the signal is supplied to the shutter on the basis of comparison with the reference voltage "REF" to regulate the impedance of the transistor Q1. The current limit is set as llim=Vref/Rvwhere llim- this is the limit current, Vrefis the reference voltage REF and Rvis the resistance of resistor Rv.

Specialists in the art it will be clear that the values for the elements of the block 100 power set tables and formulas that determine the power and energy that cause ignition of volatile material. During normal operation, the load (not shown) connected to output terminals T1 and T2, receives current, and the voltage drops under the action of the output resistance. To maximize power transmission it is desirable to limit the output impedance to the level required to prevent ignition of volatile material.

The problem is that adding unit 103 limits the average current causes additional voltage drop beyond the levels of restrictions to prevent volame is possible. The voltage drops due to the fact that the resistance of voltage conversion increases the total output resistance.

Block 200 power supply, shown in figure 2, solves this problem in accordance with the present invention. 200 unit power is intrinsically safe power supply, which limits the strength of the current, power and voltage supplied to the load (not shown). Block 201 limits voltage limits the voltage at the ends of the load. Block 201 limit voltage is a semiconductor Zener diode Z1 connected between lines 210 and 220. Specialist in the art it will be clear that to limit the voltage between lines 210 and 220 can connect more than one semiconductor Zener diode. For this description, it is possible that the block 201 limits voltage limits the voltage at the ends of the load (not shown) to level VZ.

According to the present invention, the limit function of the instantaneous and average current are combined in one unit. Use one block to perform both functions reduces the total output impedance to a value of resistance required to prevent ignition of volatile material. This is done by moving the elements of the blocks limits the average current location after a block on the limits of the instantaneous current. In particular, a variable impedance, that is, the transistor Q1, moved to a location after the barrier block. The location of the device impedance creates two new lines to the output terminals T1 and T2. New lines are the output of the operational amplifier OA feedback resistor conversion. The total output impedance is the parallel combination of resistors along the two new lines and line 210 to the power source PS.

In block 200, the power supply unit 202 current limit corresponding to the present invention, is performed as follows. The source of the field-effect transistor based on the structure type metal-oxide-semiconductor or MOS transistor Q1 is connected to the negative output terminal T2. Barrier resistor R3 is connected in line 220 between the transistor Q1 and the source PS current. The second resistor R2 is connected between the drain of the transistor Q1 and the input of the operational amplifier OA to generate a comparative voltage. Operational amplifier OA has a lower input connected to the resistor R2, and the upper input receiving the reference voltage REF. The operational amplifier compares and supplies current to the gate of the transistor Q1 to control the impedance of the transistor Q1. The resistor R1 is connected between the output of the operational amplifier OA and the gate of the transistor Q1. Specialists in the art will be Monday the IDT, what indicators of resistors R1, R2 and R3 can be high, and that the total output impedance is a combination of three parallel resistors, which is negligibly less than the value of the barrier resistance. Thus, the power transfer is optimized.

One device where you want the block 200 power supply is the power supply for the electronic component of the Coriolis flowmeter operating in a hazardous environment. Figure 3 shows the flow meter 300 Coriolis containing 200 unit power. The flow meter 300 includes Coriolis flow measuring unit 310 and the electronic measuring unit 350. Measuring electronic unit 350 is connected to a flow meter unit 310 wires 320 to transmit information, such as (but not limited to, density, mass flow rate, volumetric flow rate and total mass flow rate on line 375. The design of the Coriolis flowmeter, although experts in the art should be understood that the present invention may be implemented in connection with any device with intrinsically safe circuits requiring intrinsically safe power supply.

The design of the Coriolis flowmeter, although experts in the art should be understood that the present invention may be implemented in connection with any device having a vibrating tube for measuring the characteristics of the IR material, flowing in the pipe. Another example of such a device is the density measuring device with a vibrating pipe, which has no additional measurement capabilities, provide a mass flowmeter of the Coriolis force.

Flow measuring unit 310 includes a pair of flanges 301 and 301’, header 302 and pipe A and V. The exciter 304, testcustomer sensors 306 and 306’ and the sensor 307 temperature connected with the pipes A and B. Spacer plate 305 and 305’ are used for education axes W and W’, for which fluctuates each pipe.

When the flow meter 300 Coriolis mounted in a pipeline (not shown)which carries the process material to be measured, material enters the flow measuring unit 310 through the flange 301, passes through the manifold 302, in which the material is directed into the pipe A and V. The material then passes through the pipes A and B and back into the reservoir 302 through which he goes out of the flow measuring unit 310 through the flange 301’.

Pipe A and V chosen and properly installed on the manifold 302 so that they have essentially the same mass distribution, moments of inertia and the modulus of elasticity with respect to the axes W-W and W’-W, respectively. Pipe A-W pass out from the collector essentially parallel to each other.

Pipe A-F are driven by the agitation device 304 in the anti-Christ. roznych directions relative to the axes W and W’ of the bend and, that is, in the first anti-phase bending mode of the flow meter. Stimulating device 304 can include any of the many well-known devices such as a magnet mounted on the pipe A, and opposing coil mounted on the pipe F, through which are passed the alternating current to call vibration of both tubes. The corresponding excitation signal is fed vozbujdayuschego device 304 measuring electronic unit 350 through line 312.

Testcustomer sensors 306 and 306’ are attached at least to one of the pipes A and B at opposite ends of the pipe for measuring vibrations of the pipes. When pipes A-V vibrate, testcustomer sensors 306-306’ generate the first signal sensor and the second sensor signal. The first and second sensor signals are served at line 311 and 311’. The signal frequency of the oscillation exciter is fed into the line 312.

The sensor 307 temperature attached to at least one pipe A and/or B. The sensor 307 temperature measures the temperature of the pipe to convert the equations for the temperature of the system. Line 311 transmits the signals of the temperature sensor 307 temperature measuring electronic unit 350.

Measuring electronic unit 350 receive the first and second sensor signals received on lines 311 and 311’ respectively. Measuring electr the config block 350 processes the first and second signals of the oscillation frequency to calculate the mass flow rate, density or other properties of the material passing through the flow measuring node 30. This is obtained by calculating the information is provided electronic measuring unit 350 on line 375 consumer (not shown).

Specialists in the art it is known that the flow meter 300 Coriolis similar in design to the densitometer with the vibrating tube. In instruments with vibrating pipe is also used vibrating tube through which flows a fluid, or, in the case of densitometer sample type, which is kept liquid. In instruments with vibrating pipe is also used excitation system for excitation of vibration of the pipe. In instruments with vibrating pipe is typically used only one feedback signal, since the density measurement requires only the measurement frequency, and measuring the phase is not necessary. The description of the present invention, it is equally applicable for instruments with vibrating pipe.

In the 300 meter Coriolis measuring electronic unit 350 is physically separated two components: the host system 370 and 360 Converter signals. In conventional measuring electronic unit these components are assembled in one unit.

The Converter 360 signals contains the block 363 excitation and block 361 conversion of sensor signals. The person skilled in the art technical and it will be clear, what actually block 363 excitation and block 361 conversion of sensor signals can be separate analog circuits or can perform specific functions provided by the processor for digital signal processing or other digital components. Unit 363 excitation generates the excitation signal and supplies an excitation signal to the exciter 304 on line 312 in line 320. In practice, line 312 are first and second wires. Unit 363 excitation is attached to a pulley 361 conversion of the sensor signal line 362. Line 362 provides a current control unit excitation of the incoming sensor signals for regulation of the excitation signal. Power for the unit 363 excitation and block 361 conversion of sensor signals gives the host system 370 on the first wire 373 and the second wire 374. The first wire 373 and the second wire 374 can be part of a normal wire, four-wire cable or a part of a multi-conductor cable.

Block 361 of the signal sensor receives incoming signals from the first sensor 305, a second sensor 305’ and sensor 307 temperature lines 311, 311’ and 311’. Block 361 conversion of sensor signals determines the frequency of the sensor signals and may also determine the properties of the material flowing through the pipes A-W. After determining the frequency of the input signals from those who sotushilnyh sensors 305-305’ and material properties are formed the signal parameters, containing this information, and transmitted to the secondary processor 371 in the host system 370 on line 376. In a preferred embodiment of the invention, line 376 includes two wires. However, the specialist in the art will understand that line 376 can be combined with the first wire 373 and the second wire 374 or any number of other wires.

The host system 370 includes a block 372 power supply and the CPU 371. Block 372 power supply receives power from a power source and converts the received power to the appropriate power required by the system. The CPU 371 receives signals from block 361 conversion of sensor signals and can then carry out the processing necessary to determine the required user properties flowing in pipes A-V material. Such properties may include, but are not limited to, density, mass flow and volume flow.

In this embodiment of the invention, block 372 food contains the schema 200 power supply, shown in figure 2. This provides a supply unit 372 supply power corresponding to the constraints intrinsic safety, the Converter 360 signal that contains the schema corresponding to the standards for intrinsic safety.

1. Intrinsically safe device (200)configured to supply power to the load, the United States is Yu from the first output terminal (T1) and the second output terminal (T2), the specified device contains the power (PS) power; a limiter (Z1) voltage, connected in parallel to the power source, to limit the magnitude of the voltage generated by the power source; a connection between the first side of the limiter voltage and the first output terminal; a limiter (202) current, is connected between the second side of the limiter voltage and the second output terminal, and a current limiter includes a barrier resistor; variable impedance; a comparator; wherein the current limiter further comprises a barrier resistor (R3); AC impedance (Q1)connected between the second output terminal and the first side of the barrier resistor; while the second side of the barrier resistor connected from the second side of the limiter voltage; a reference voltage is connected to the input of the comparator; the comparator output is connected with the control input of the variable impedance; a signal generated by the comparator output to the control input of the variable impedance controls the magnitude of the impedance of the specified variable impedance; and the connection between the first side barrier resistor and the comparator input to receive voltage represents the current strength in the barrier resistor; a comparator compares the value of the reference voltage and the voltage taken from the defence is REGO resistor, to limit to a maximum level of current supplied to the load through the output terminals.

2. Intrinsically safe device according to claim 1, characterized in that it further comprises a fuse (F1)is connected between the positive side voltage of the power source and the voltage suppressor.

3. Intrinsically safe device according to claim 1, wherein the voltage limiter includes a diode having a cathode connected to the positive side of the power source, and the anode connected to the negative side of the power source.

4. Intrinsically safe device according to claim 3, wherein the voltage limiter includes a semiconductor Zener diode.

5. Intrinsically safe device according to claim 1, characterized in that the limiter current AC impedance includes a transistor connected between the first side barrier resistor and the second output terminal, for regulating the current supplied to the load; a comparator is an operational amplifier (OA), which regulates the impedance of the transistor; a comparator has an output connected with the control input of the transistor; a comparator additionally has a first input connected to a voltage representing the magnitude of the load current, and a second input connected to the reference voltage; and a voltage divider barrier contains a resistor is La generation voltage, representing the load current, and a voltage divider connected to the first input of the operational amplifier and the negative side of the power source.

6. Intrinsically safe device according to claim 5, wherein the current limiter further comprises a resistor (R1)connected between the output of the operational amplifier and control input of the transistor.

7. Intrinsically safe device according to claim 5, characterized in that the current limiter transistor includes a field effect transistor based on the structure type metal-oxide-semiconductor (MOS transistor).

8. Intrinsically safe apparatus according to claim 7, characterized in that the current limiter and the voltage divider includes a first resistor (R2)connected between the first input of the operational amplifier and the drain of the transistor; the barrier resistor (R3)having a first side connected to the specified flow, and a second side connected to the negative side of the power source.

9. Intrinsically safe device according to claim 1, characterized in that the load contains an electronic unit of a Coriolis flowmeter having the transformation block signal to generate excitation signal and for receiving sensor signals and the power signal conversion is connected with the first and second output terminals of the intrinsically safe device.

10. Intrinsically safe device according to claim 9, great for the different themes, that block conversion of the signal further comprises the AC excitation signal excitation, and block the excitation is connected with the first and second output terminals of the intrinsically safe device; a conversion unit signal of a Coriolis flowmeter for receiving sensor signals and the power signal conversion has an input connected to the output of the excitation.

11. The method of operation of an intrinsically safe device for supplying power to the load through the first and second output terminals, while this method contains the following steps: connect the voltage suppressor in parallel with the power source to limit the magnitude of the voltage generated by the power source; provide the connection between the first side of the limiter voltage and the first output terminal; characterized in that the method comprises the following additional steps: connect the first side of the barrier resistor in series with a variable impedance to the second output terminal; a second connection side of the limiter voltage from the second side of the barrier resistor; carry out the operation of the comparator for comparing the reference voltage with the voltage at the ends of the barrier resistor, representing the strength of the current supplied to the load through the output to the Emmy; providing a control signal from the specified comparator output to the control input of the variable impedance; carry out the operation of the variable impedance in response to receiving the control signal, to limit the maximum current passing through the barrier resistor and a variable impedance to the load.

12. The method according to claim 11, characterized in that the step of limiting the voltage level includes a phase diode for voltage limitation.

13. The method according to item 12, characterized in that the phase diode includes a phase of operation of the semiconductor Zener.

14. The method according to claim 11, characterized in that it further comprises the following steps:

intrinsically safe power from the output terminals in the AC excitation of the Coriolis flowmeter and the formation of the excitation signal block excitation, in response to reception of the specified capacity.

15. The method according to 14, characterized in that it further comprises the step of sending the signals of the sensors in the unit conversion signal of the Coriolis flowmeter, in response to reception of the specified capacity.

16. The method according to claim 11, characterized in that the step of limiting the maximum current delivered to a load, includes the following steps: perform the operation of the voltage divider to generate a voltage that represents si is the current supplied to the load through the barrier resistor; the functioning of the operational amplifier for comparing the reference voltage with a voltage representing the current supplied to the load; providing a signal from the output of the operational amplifier to the control input of the transistor, defining a variable impedance to limit the current supplied to the load.

17. The method according to 14, characterized in that the phase of operation of the transistor includes the phase of operation of the MOSFET.

18. Intrinsically safe device (200)configured to supply power to a load connected to the first output terminal (T1) and the second output terminal (T2), and the specified device contains the power (PS) power; a limiter (Z1) voltage, connected in parallel with the power source, to limit the maximum voltage generated by the power source; a connection between the first side of the limiter voltage and the first output terminal; characterized in that said device includes a limiter (202) current, is connected between the second side of the limiter voltage and the second output terminal, the current limiter includes reference voltage, a variable impedance (Q1), barrier resistor (R3) and the second side of the voltage limiter connected in series with the barrier resist the rum and a variable impedance to the second output terminal, the current limiter limits the current supplied to the load through these output terminals, up to the maximum level of current by comparing the reference voltage with the voltage at the ends of the barrier resistor.

19. The method of operation of an intrinsically safe device for supplying power to the load, containing the following steps: connect the voltage suppressor in parallel with the power source to limit the maximum voltage generated by the power source; provide the connection between the first side of the limiter voltage and the first output terminal; connect the second side of the voltage limiter in series with the barrier resistor and a variable impedance to the second output terminal; shall limit the current supplied to the load through the output terminals, up to the maximum level of current depending on the comparison of the reference voltage with the voltage at the ends of the barrier resistor representing the current supplied to the load through the barrier resistor and output terminals.



 

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Voltage converter // 2036510

FIELD: power units designed to ensure spark safety of loads.

SUBSTANCE: proposed device 200 designed to supply with power spark-proof load provided with feedback circuit of integrated current supply and current limiting component and also to minimize voltage that should be limited in compliance with sparking safety standards has power supply PS and output terminals T1-T2 for connecting device to spark-proof load. Voltage limiting unit Z1 inserted between power supply PS and output terminals T1-T2 is used to limit voltage across load leads. Current limiting unit 202 has barrier resistors designed for current-to-voltage conversion to provide for comparison by operational amplifier that controls variable impedance Q1 and limits current supply to load.

EFFECT: reduced manufacturing cost, improved sparking safety.

19 cl, 3 dwg

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