Strong anti-interference isolation type input acquisition module of transformer area intelligent fusion terminal

Abstract

The utility model discloses a transformer area intelligent fusion terminal strong anti-interference isolation type input acquisition module. The transformer area intelligent fusion terminal strong anti-interference isolation type input acquisition module comprises an on-site input and grading protection circuit, an optical coupler isolation and drive circuit and a logic side shaping output circuit. The output end of the field input and grading protection circuit is electrically connected with the input end of the optical coupling isolation and driving circuit; the output end of the optocoupler isolation and drive circuit is electrically connected with the input end of the logic side shaping output circuit; the optical coupler isolation and drive circuit realizes electrical isolation of the input side and the logic side. The transformer area intelligent fusion terminal strong anti-interference isolation type input acquisition module has the characteristics of graded energy management, strong anti-interference, reliable electrical isolation and easy deployment and maintenance.

Description

TECHNICAL FIELD

[0001] The utility model relates to the on -the -spot quantity collection and safe isolation technology of distribution area intelligent fusion terminal, concretely relates to a strong anti -interference isolation type input collection module of distribution area intelligent fusion terminal. BACKGROUND

[0002] With the further promotion of intelligent power grid construction, as the core equipment of the end of distribution network, distribution area intelligent fusion terminal bears important functions such as data acquisition, state monitoring, remote communication etc. The distribution area field input signal source is complex and various, mainly including box alarm contact, circuit breaker auxiliary contact, door magnetic / water immersion sensor, relay output and pulse metering signal etc. The common characteristics of these signals are long wiring distance, and long-term exposure in strong electromagnetic interference environment.

[0003] Under the distribution area field environment, the traditional input acquisition circuit faces a variety of typical risks and technical problems. First, the transient overvoltage threat, lightning induced surge, electrostatic discharge and other transient overvoltage events can cause front-end circuit device breakdown, seriously affecting the reliability of the equipment. Secondly, the signal integrity problem, the common mode interference and high frequency burr signal introduced by long distance wiring are easy to cause the acquisition circuit to trigger, causing system false alarm or omission. In addition, the mechanical contact characteristic problem can not be ignored, the mechanical jitter of the field contact closure or opening and the electromagnetic coupling effect, easy to cause the same event to be recorded by multiple sampling. At the same time, there is a ground potential difference between the control board and the field device, which may be conducted to the logic side through the signal return circuit, causing impact damage to the main control circuit.

[0004] The traditional protection scheme has obvious limitations. The traditional protection scheme relying on single TVS tube or single optical coupling has defects that transient can be carried but continuous overcurrent burns and filter deficiency misfires cannot be solved. Therefore, the distribution area intelligent fusion terminal urgently needs an input collection module that can adapt to the complex field conditions, which should have hierarchical energy management capability, strong anti-interference performance and reliable electrical isolation function. UTILITY MODEL CONTENT

[0005] The utility model aims at providing a strong anti-interference isolation type input collection module of distribution area intelligent fusion terminal. The strong anti-interference isolation type input collection module of distribution area intelligent fusion terminal has the characteristics of hierarchical energy management, strong anti-interference, reliable electrical isolation and easy deployment and maintenance.

[0006] The utility model discloses an above-mentioned technical purpose is realized through the following technical schemes: a strong anti-interference isolation type input acquisition module of intelligent fusion terminal of district, including field input and hierarchical protection circuit, photoelectric coupler isolation and drive circuit, logic side shaping output circuit, field input and hierarchical protection circuit's output terminal with photoelectric coupler isolation and drive circuit's input terminal electricity is connected, photoelectric coupler isolation and drive circuit's output terminal with logic side shaping output circuit's input terminal electricity is connected, photoelectric coupler isolation and drive circuit realize the electrical isolation of input side and logic side.

[0007] The utility model further sets up: field input and hierarchical protection circuit including self -restoring PTC thermistor (F7), TVS pipe (TVS14), first magnetic bead (FB11), second magnetic bead (FB12) and high frequency bypass capacitor (C90), self -restoring PTC thermistor (F7) is connected between field positive input terminal (YX1+) and protection node, TVS pipe (TVS14) is connected between protection node and field input loop reference line (COM), first magnetic bead (FB11) is connected on the input positive channel between protection node and photoelectric coupler isolation and drive circuit, second magnetic bead (FB12) is connected on loop reference channel, high frequency bypass capacitor (C90) is connected between the node after first magnetic bead (FB11) and field side reference ground (GND1).

[0008] The utility model further sets up: photoelectric coupler isolation and drive circuit including photoelectric coupler (OP10), current -limiting resistance (R129) and decoupling capacitor (C88), decoupling capacitor (C88) is connected between input side power supply (VCC_485) and field side reference ground (GND1), one end of current -limiting resistance (R129) is connected input side power supply (VCC_485), the other end of current -limiting resistance (R129) is connected photoelectric coupler (OP10)'s LED anode, photoelectric coupler (OP10)'s LED cathode is connected to field side reference ground (GND1) or through second magnetic bead (FB12) loop connection.

[0009] The utility model further sets up: the logic side shaping output circuit includes pull -up resistance (R127), series speed limiting resistance (R128) and shaping capacitor (C89), one end of pull -up resistance (R127) connects logic side pull -up power (VCC3V3), the other end of pull -up resistance (R127) is connected the light coupling (OP10) photosensitive transistor collector node, one end of series speed limiting resistance (R128) is connected the light coupling (OP10) photosensitive transistor collector node, the other end of series speed limiting resistance (R128) is connected master control side digital quantity output port (YX1), shaping capacitor (C89) is connected between master control side digital quantity output port (YX1) with ground.

[0010] The utility model further sets up: input side power supply (VCC_485) with logic side pull -up power (VCC3V3) is the power domain of mutual independence, the light coupling (OP10) will input side power domain with logic side power domain electrical isolation.

[0011] The utility model further sets up: the self -restoring PTC thermistor (F7) is low resistance state in normal operation, and resistance rises into current -limiting protection state when overcurrent, TVS pipe (TVS14) is used to carry out the quick clamping of transient overvoltage, the first magnetic pearl (FB11) with second magnetic pearl (FB12) is used to suppress high -frequency noise and limit the current change rate of surge peak.

[0012] The utility model further sets up: the resistance of current -limiting resistance (R129) is 680Ω, the resistance of pull -up resistance (R127) is 2.2kΩ, the resistance of series speed limiting resistance (R128) is 100Ω, the capacity of decoupling capacitor (C88) is 100nF, the capacity of shaping capacitor (C89) is 30pF, the capacity of high frequency bypass capacitor (C90) is 330pF.

[0013] The utility model further sets up: the self -restoring PTC thermistor (F7) adopts model number MZ11-10A300-600RM, TVS pipe (TVS14) adopts model number SMBJ6.0CA, the first magnetic pearl (FB11) with second magnetic pearl (FB12) all adopt model number HB-1M2012-102, the light coupling (OP10) adopts model number TLP785B+.

[0014] Summarized above, the utility model has following beneficial effect:

[0015] 1. Hierarchical energy management: The utility model discloses a combined hierarchical energy management architecture of PTC current limiting, TVS clamping, double magnetic bead speed limiting and high-frequency bypass capacitor, realizes the hierarchical energy management of transient overvoltage by TVS, continuous overcurrent by PTC and high-frequency interference by magnetic beads and capacitor, can not only deal with transient events such as ESD and lightning surge, but also effectively deal with the continuous overcurrent problem caused by the post-surge power frequency following current and miswiring, can significantly reduce the risk of TVS thermal breakdown and the risk of optocoupler LED overcurrent aging.

[0016] 2. Power domain separation and bilateral decoupling: The utility model discloses that the input side and the logic side power domain are separated, the LED side uses VCC_485 power supply and configures independent decoupling capacitor (C88), the logic side uses VCC3V3 and carries out pull-up output, and the energy passage is disconnected through the optocoupler on both sides, so that external cable interference is difficult to be connected into the MCU domain through the power loop, and the whole machine anti-interference and system reliability are significantly improved.

[0017] 3. Anti-glitch digital interface: The utility model discloses that the RC filter network of small time constant is formed by series limiting resistor (R128) and shaping capacitor (C89) on the logic output side, under the premise of not obviously reducing response speed, the glitch interference introduced by the optocoupler switch and long line coupling is effectively inhibited, and the system false alarm rate can be significantly reduced.

[0018] 4. The utility model discloses the application scene of intelligent fusion terminal in the transformer area, and the device parameter combination and current working point are optimized, and the matching setting of LED side working current about 5.5mA and logic side pull-up current about 1.4mA makes the input end have strong anti-interference threshold, and the output end has sufficient pull-down margin and fast recovery capacity, and power consumption control and device life requirement are considered.

[0019] 5. The utility model discloses that the self-recovery PTC device is used to replace the traditional one-time fuse, can automatically reset after fault recovery, reduces the workload of on-site maintenance and device replacement, and is suitable for the long-term operation mode of unattended transformer terminal. ACCURACY OF DRAWINGS

[0020] Figure 1 It is the overall circuit schematic diagram of the utility model. DETAILED DESCRIPTION

[0021] In the description of the utility model, it is to be explained that the orientation or positional relationship indicated by the terms input side, output side, logic side and the like is the orientation or positional relationship shown based on signal flow, only for the convenience of describing the utility model and simplifying the description, and is not to indicate or imply that the indicated device or element must have a particular orientation, structure and operation, therefore can not be understood as the limitation of the utility model.

[0022] As Figure 1 shown, the utility model provides a kind of intelligent fusion terminal strong anti-interference isolation type input acquisition module of transformer area, which adopts the structure of PTC current limiting, TVS clamping, magnetic bead suppression, RC filtering, opto-isolator isolation, logic side pull-up / limiting speed shaping.The module can be divided into three functional segments according to signal flow direction, which are field input and hierarchical protection circuit, opto-isolator isolation and driving circuit, logic side shaping output circuit in turn from field input end to logic output end.

[0023] Field input and hierarchical protection circuit is responsible for providing hierarchical energy management and EMI suppression function, and completes the suppression and bypass processing of overcurrent, overvoltage and high-frequency burr before the signal enters the isolating device.The circuit includes self-recovery PTC thermistor (F7), TVS tube (TVS14), first magnetic bead (FB11), second magnetic bead (FB12) and high-frequency bypass capacitor (C90).

[0024] Self-recovery PTC thermistor (F7) adopts model MZ11-10A300-600RM, is connected in series between field positive input end (YX1+) and protection node, is in low resistance state during normal operation, and the resistance value rises sharply into high resistance current limiting state when overcurrent, effectively preventing TVS tube and opto-coupler from being damaged due to continuous overcurrent heating.When the fault is removed and the circuit temperature drops, it can automatically recover to low resistance state without manual replacement.

[0025] TVS tube (TVS14) adopts model SMBJ6.0CA bidirectional TVS tube, is connected between protection node and field input loop reference line (COM), and is used for fast clamping of transient overvoltage, clamping overvoltage to a safe level and discharging transient energy to COM loop.

[0026] First magnetic bead (FB11) and second magnetic bead (FB12) both adopt model HB-1M2012-102, first magnetic bead (FB11) is connected in series on input positive channel between protection node and opto-coupler isolation and driving circuit, and second magnetic bead (FB12) is connected in series on loop reference channel, which cooperates to realize differential mode / common mode high frequency suppression and limit the current change rate of surge peak at the same time.High-frequency bypass capacitor (C90) has a capacitance of 330pF, is connected between the node after first magnetic bead (FB11) and field side reference ground (GND1), and cooperates with magnetic bead to absorb ns to µs level peak signal.

[0027] Opto-coupler isolation and driving circuit drives opto-coupler LED through current limiting resistor with field side input signal after protection and filtering processing, to realize electrical isolation with MCU logic side.

[0028] The circuit includes an optocoupler (OP10), a current-limiting resistor (R129), and a decoupling capacitor (C88). The optocoupler (OP10) is a TLP785B+ model, an LED input / phototransistor output type optocoupler, providing electrical isolation between the input and logic sides. The decoupling capacitor (C88) has a capacitance of 100nF and is connected between the input-side power supply (VCC_485) and the field-side reference ground (GND1) to stabilize the power supply, suppress power fluctuations, ensure stable power supply, and maintain the consistency of the optocoupler's trigger threshold. The current-limiting resistor (R129) has a resistance of 680Ω, with one end connected to the input-side power supply (VCC_485) and the other end connected to the LED anode of the optocoupler (OP10), setting the LED forward current to approximately 5.51mA. The LED cathode of the optocoupler (OP10) is connected to the field-side reference ground (GND1) or via a loop through the second ferrite bead (FB12).

[0029] The logic-side shaping output circuit converts the open-collector output of the optocoupler into a digital level signal readable by the external main control MCU. This circuit includes a pull-up resistor (R127), a series speed-limiting resistor (R128), and a shaping capacitor (C89). The pull-up resistor (R127) has a resistance of 2.2kΩ, with one end connected to the logic-side pull-up power supply (VCC3V3) and the other end connected to the collector node of the phototransistor of the optocoupler (OP10), used to set the pull-up current to approximately 1.4mA and form a digital level. The series speed-limiting resistor (R128) has a resistance of 100Ω, with one end connected to the collector node of the phototransistor of the optocoupler (OP10) and the other end connected to the main control side digital output port (YX1), used to suppress reflections and crosstalk caused by excessively fast signal edges. The shaping capacitor (C89) has a capacitance of 30pF and is connected between the main control side digital output port (YX1) and ground. Together with the series speed limiting resistor (R128), it forms an RC low-pass filter network to eliminate switching spikes and coupling glitches.

[0030] The circuit adopts an architecture that separates the power supply domains on the input and logic sides. The input / LED side uses the VCC_485 power supply domain and is configured with an independent decoupling capacitor (C88), while the logic side uses the VCC3V3 power supply domain for pull-up output. Electrical isolation between the two power supply domains is achieved through an optocoupler (OP10), which disconnects the energy coupling path and ensures that external cable interference cannot enter the MCU domain through the power supply loop.

[0031] The working principle of this utility model is as follows:

[0032] Normal input triggering process: When the external contact is closed or the output is valid, the field input signal first enters the circuit through the field positive input terminal (YX1+), forming a complete current loop path with the field input loop reference line (COM). The current flows through the self-resetting PTC thermistor (F7), which is in a normal low-resistance state at this time, and the signal reaches the protection node. Subsequently, the signal passes through the first ferrite bead (FB11) and the second ferrite bead (FB12), where high-frequency components are suppressed, and the high-frequency bypass capacitor (C90) bypasses the residual spike signal at high frequency. The filtered signal enters the optocoupler drive circuit. Under the current limiting effect of the current limiting resistor (R129), the LED of the optocoupler (OP10) receives approximately 5.5mA of forward drive current and lights up. The phototransistor inside the optocoupler conducts after receiving the light signal, pulling the collector node potential low.

[0033] On the logic output side, the conduction of the optocoupler transistor causes the collector node voltage, which was originally pulled up to VCC3V3 by the pull-up resistor (R127), to drop. This level change signal is then output to the main control side digital output port (YX1) after passing through the RC shaping network composed of the series speed limiting resistor (R128) and the shaping capacitor (C89), for the main control MCU to read.

[0034] When an external cable experiences a lightning surge or electrostatic discharge event, the transient overvoltage energy is first rapidly processed by the TVS diode (TVS14). The TVS diode (TVS14) quickly conducts upon the arrival of the overvoltage, clamping it to a safe level and discharging the transient energy into the COM circuit. Simultaneously, the first ferrite bead (FB11) and the second ferrite bead (FB12) limit the rate of change of the surge current, and the high-frequency bypass capacitor (C90) further absorbs the high-frequency surge energy, collectively reducing the impact of the surge energy on the subsequent optocoupler.

[0035] In the event of a sustained overcurrent, the self-resetting PTC thermistor (F7) provides protection. The PTC heats up due to the overcurrent, causing its resistance to rise sharply, entering a high-resistance current-limiting state. This effectively prevents the TVS diode and optocoupler from overheating and being damaged due to sustained overcurrent. Once the fault is cleared and the circuit temperature drops, the PTC automatically returns to a low-resistance state, requiring no manual replacement.

[0036] This utility model presents a high-reliability, anti-interference, and isolation-type input acquisition module for intelligent integrated terminals in distribution transformer areas. Through a combined hierarchical energy management architecture using PTC current limiting, TVS clamping, dual ferrite bead speed limiting, and high-frequency bypass capacitors, along with power domain separation and anti-glitch digital interface settings, it solves the technical challenges faced by traditional input acquisition circuits in distribution transformer area environments, such as transient overvoltage threats, signal integrity issues, mechanical contact characteristics, and ground potential difference impacts. This achieves high reliability and strong anti-interference performance for the input acquisition of intelligent integrated terminals in distribution transformer areas, and has good application value.

[0037] To verify the above technical solution, this utility model tests the strong anti-interference isolation type input acquisition module of the intelligent converged terminal in the distribution area.

[0038] The verification method employs comparative testing, using a traditional single TVS diode and single optocoupler input acquisition circuit as the control group and the module of this utility model as the experimental group, measuring performance indicators under the same test conditions. Surge immunity testing is conducted according to IEC 61000-4-5 standard, electrostatic discharge immunity testing according to IEC 61000-4-2 standard, electrical isolation performance testing according to GB / T 16935.1 standard, signal integrity testing using simulated field contact signals superimposed with high-frequency glitches, and long-term reliability testing using continuous 72-hour operation with periodic overcurrent impacts.

[0039] Technical Effect Comparison Table

[0040] Performance indicators Conventional technology The utility model technology Lifting range Lifting instructions Surge tolerance Single-stage TVS protection, TVS is easy to thermal breakdown after bearing 2kV surge PTC current limiting, TVS clamping, double magnetic bead speed limiting combination, circuit is intact after bearing 4kV surge Surge tolerance is improved by 100% TVS tube (SMBJ6.0CA) fast clamping transient energy, self-recovery PTC thermistor (F7) handles subsequent power frequency following current, magnetic bead (FB11 / FB12) limits di / dt, three-stage cooperation avoids single device overload Continuous overcurrent protection and recovery One-time fuse fusing, manual replacement is needed, and recovery time is greater than or equal to 30 minutes Self-recovery PTC device (MZ11-10A300-600RM) automatically recovers conduction after fault removal, and the recovery time is about 2 minutes Maintenance cost is reduced by 100%, and recovery time is shortened by 93% PTC overcurrent resistance limiting protection rear circuit, automatically restores low resistance state after temperature drops, and is suitable for unattended long-term operation mode of terminal in transformer substation Electrical isolation and common mode interference resistance Single optocoupler isolation, common mode interference is easy to pass through the power supply loop and enter the MCU domain, and the isolation withstand voltage is 1kV Optocoupler isolation, power supply domain separation, double-sided independent decoupling, isolation withstand voltage is 2.5kV, and common mode rejection ratio is improved Isolation withstand voltage is improved by 150%, and system reliability is significantly improved Input side VCC_485 and logic side VCC3V3 are completely independent, optocoupler (TLP785B+) disconnects energy coupling path, and decoupling capacitor (C88 / 100nF) stabilizes respective power supply domains Glare suppression and misfire rate No special filter network, high-frequency glitches are directly conducted, and the misfire rate is about 5%~8% Double magnetic beads, high-frequency bypass capacitor (330pF) and output RC shaping (100Ω / 30pF), misfire rate is reduced to below 0.3% Misfire rate is reduced by more than 95% Magnetic beads suppress high-frequency noise, C90 bypasses ns~µs level spikes, and R128 and C89 constitute a small time constant RC network to eliminate switching spikes and coupled glitches Current operating point optimization and device life LED driving current fluctuates greatly (3~10mA), and the optocoupler ages quickly, with a service life of about 3 years LED current is stable at about 5.5mA, and pull-up current is about 1.4mA, and the service life is expected to be extended to more than 5 years Device life is extended by more than 67% Current limiting resistor (R129 / 680Ω) accurately sets the LED working current, and pull-up resistor (R127 / 2.2kΩ) ensures sufficient pull-down margin, and considers the anti-interference threshold and power consumption control

[0041] 3. Verification Conclusion

[0042] Through comparative testing, the PTC current limiting, TVS clamping, dual ferrite bead speed limiting, and high-frequency bypass capacitor of this utility model's intelligent integrated terminal for transformer substations demonstrate that transient overvoltage is handled by TVS, continuous overcurrent by PTC, and high-frequency interference by ferrite beads and capacitors, thereby improving surge tolerance to the 4kV level. At the same time, the fault recovery time is shortened from more than 30 minutes to about 2 minutes through the self-recovering PTC device.

[0043] Power domain separation and optocoupler isolation increase the isolation withstand voltage to 2.5kV, blocking external cable interference from entering the MCU domain through the power circuit. The glitch-resistant digital interface, composed of a series speed-limiting resistor (R128 / 100Ω) and a shaping capacitor (C89 / 30pF), reduces the false trigger rate by over 95%. The parameter ratio of approximately 5.5mA operating current on the LED side and approximately 1.4mA pull-up current on the logic side extends the device's lifespan.

[0044] Comprehensive verification results show that this utility model meets the high reliability data acquisition and long-term unattended operation requirements of the intelligent fusion terminal for distribution radio areas in complex field environments such as strong electromagnetic interference, lightning surges, and long-distance cabling, and has broad application prospects.

Claims

1. A strong anti-interference isolation input acquisition module for a smart fusion terminal in a distribution area, characterized in that, include: Field input and hierarchical protection circuit, optocoupler isolation and drive circuit, and logic-side shaping output circuit; The output terminal of the field input and graded protection circuit is electrically connected to the input terminal of the optocoupler isolation and drive circuit. The output terminal of the optocoupler isolation and driving circuit is electrically connected to the input terminal of the logic-side shaping output circuit; The field input and graded protection circuit includes a positive input channel consisting of a self-resetting PTC thermistor (F7) and a first ferrite bead (FB11) connected in series, a second ferrite bead (FB12) connected in series on the loop reference channel, and a TVS tube (TVS14) connected between the protection node between the self-resetting PTC thermistor and the first ferrite bead and the field input loop reference line (COM). The optocoupler isolation and driving circuit includes an optocoupler (OP10), the input terminal of which is connected to the input power supply (VCC_485) via a current-limiting resistor (R129). The logic-side shaping output circuit includes a pull-up resistor (R127) and a series speed-limiting resistor (R128) connected sequentially between the optocoupler output terminal and the main control side digital output port (YX1), and a shaping capacitor (C89) connected between the main control side digital output port and ground. The input-side power supply (VCC_485) and the logic-side pull-up power supply (VCC3V3) are independent power domains, and the optocoupler achieves electrical isolation between the input side and the logic side.

2. The input acquisition module according to claim 1, characterized in that, The field input and graded protection circuit includes a high-frequency bypass capacitor (C90); the high-frequency bypass capacitor (C90) is connected between the node after the first ferrite bead (FB11) and the field-side reference ground (GND1).

3. The input acquisition module according to claim 2, characterized in that, The optocoupler isolation and driving circuit includes a decoupling capacitor (C88); the decoupling capacitor (C88) is connected between the input power supply (VCC_485) and the field reference ground (GND1); one end of the current limiting resistor (R129) is connected to the LED anode of the optocoupler (OP10); the LED cathode of the optocoupler (OP10) is connected to the field reference ground (GND1) or connected via the second ferrite bead (FB12) circuit.

4. The input acquisition module according to claim 3, characterized in that, The logic-side shaping output circuit includes a shaping capacitor (C89); the shaping capacitor (C89) is connected between the main control side digital output port (YX1) and ground.

5. The input acquisition module according to claim 4, characterized in that, The current-limiting resistor (R129) has a resistance of 680Ω, the pull-up resistor (R127) has a resistance of 2.2kΩ, and the series speed-limiting resistor (R128) has a resistance of 100Ω; the decoupling capacitor (C88) has a capacitance of 100nF, the shaping capacitor (C89) has a capacitance of 30pF, and the high-frequency bypass capacitor (C90) has a capacitance of 330pF.

6. The input acquisition module according to claim 5, characterized in that, The self-resetting PTC thermistor (F7) is model MZ11-10A300-600RM; the TVS tube (TVS14) is model SMBJ6.0CA; the first ferrite bead (FB11) and the second ferrite bead (FB12) are both model HB-1M2012-102; the optocoupler (OP10) is model TLP785B+.

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