Method for eliminating static electricity of pre-oxidized fiber yarn

Abstract

The invention relates to the technical field of pre-oxidized fiber yarn static electricity removing, in particular to a pre-oxidized fiber yarn static electricity removing method which comprises the following steps that pre-oxidized fiber yarn passes through a guiding assembly, and the yarn is guided to run along a set conveying path; the guide assembly is driven by the driving assembly, so that the yarn runs along the conveying path at a set speed; the humidifying assembly is used for adjusting the surface humidity of the yarn to reduce static accumulation; positive and negative ions in air are ionized through the static electricity eliminating assembly, and static electricity on the surface of the yarn is neutralized; detecting the electrostatic potential on the surface of the yarn by using a detection assembly, and transmitting a detection result to a control system; the control system dynamically adjusts working parameters of the static elimination assembly according to a detection result; and the yarn subjected to electrostatic treatment is guided to an outlet. Static electricity is reduced through the static electricity elimination assembly and the humidification assembly, the detection mechanism assembly monitors the static electricity potential, and the control system adjusts the working parameters of the static electricity elimination assembly, so that the processing quality of the pre-oxidized yarn is improved.

Description

Technical Field

[0001] The present invention relates to the technical field of antistatic technology for pre-oxidized yarns, and particularly to a method for removing static electricity from pre-oxidized yarns. Background Art

[0002] Pre-oxidized yarn is a special fiber material that has been pre-oxidized, with excellent high-temperature resistance, flame retardancy, and chemical stability. It is widely used in the production and manufacturing processes of fireproof clothing, high-performance composite materials, and carbon fiber precursors. During the production and processing of pre-oxidized yarns, due to their special chemical composition and surface characteristics, friction occurs between the yarns and between the yarns and the surface of the equipment. This friction easily leads to charge redistribution on the surface of the yarns, and then the yarns carry static charges. The accumulation of static electricity not only affects the winding quality of the yarns but may also cause problems such as yarn entanglement, adhesion, and equipment failures, seriously affecting the normal production process. Therefore, effective control of static electricity becomes a key issue during the processing and winding of pre-oxidized yarns.

[0003] Currently, to solve the static electricity problem in the processing of pre-oxidized yarns, various antistatic technologies have been developed in the industry. However, these methods are basically developed from the perspective of how to remove static electricity. Therefore, there is an urgent need to develop a more adaptable method for removing static electricity from pre-oxidized yarns, so as to further improve the static electricity control effect and ensure the high-quality processing and stable production of pre-oxidized yarns. Summary of the Invention

[0004] In view of at least one of the above technical problems, the present invention provides a method for removing static electricity from pre-oxidized yarns, which uses a variety of ways to eliminate charges to remove static electricity from the pre-oxidized yarns.

[0005] A method for removing static electricity from pre-oxidized yarns is provided, including the following steps: Pass the pre-oxidized yarn through a guiding component to guide the yarn to run along a set conveying path; Use a driving component to drive the guiding component so that the yarn runs along the conveying path at a set speed; Use a humidifying component to adjust the surface humidity of the yarn to reduce static electricity accumulation; Ionize positive and negative ions in the air through an electrostatic elimination component to neutralize the static electricity on the surface of the yarn; Use a detection component to detect the static electricity potential on the surface of the yarn and transmit the detection result to a control system; The control system dynamically adjusts the working parameters of the electrostatic elimination component according to the detection result; Guide the yarn after static electricity treatment to an outlet.

[0006] In some embodiments of the present invention, the humidifying component adjusts the surface humidity of the yarn by spraying water mist, and the particle size range of the water mist is 10 μm to 50 μm.

[0007] In some embodiments of the present invention, the static eliminator assembly includes a DC high-voltage power generator, a discharge electrode, and a static bar. The static bar is installed at a position not greater than 300 mm from the surface of the yarn, and three yarns pass through the length range of the static bar simultaneously.

[0008] In some embodiments of the present invention, the static eliminator assembly ionizes positive and negative ions in the air to neutralize the static electricity on the surface of the yarn, and further includes the following steps: Apply a high voltage to the tip of the discharge electrode through a power generator to generate corona discharge; Ionize the air into a large number of positive and negative ions; Use the positive and negative ions diffused in the air to neutralize the static electricity on the surface of the yarn.

[0009] In some embodiments of the present invention, the yarn runs along the conveying path at a speed of 10 m / min to 50 m / min.

[0010] In some embodiments of the present invention, the surface of the guiding assembly is coated with a ceramic layer.

[0011] In some embodiments of the present invention, the diameter range of the guiding assembly is 150 mm - 200 mm.

[0012] In some embodiments of the present invention, the detection assembly is a non-contact static electricity potential sensor, and the detection range is -10 kV to +10 kV.

[0013] In some embodiments of the present invention, using the detection assembly to detect the static electricity potential on the surface of the yarn and transmit the detection result to the control system includes the following steps: Set a non-contact static electricity potential sensor as the detection assembly for detecting the static electricity potential on the surface of the yarn; The detection assembly collects static electricity potential data in real time during the running of the yarn, and the collection frequency is 10 Hz to 100 Hz; Transmit the collected static electricity potential data to the control system through a data transmission module; The control system compares the received static electricity potential data with a preset static electricity potential safety threshold; If the static electricity potential is lower than the preset threshold, maintain the working parameters of the current static eliminator assembly; If the static electricity potential is higher than the preset threshold, calculate the error value and dynamically adjust the working parameters of the static eliminator assembly to reduce the static electricity potential on the surface of the yarn.

[0014] In some embodiments of the present invention, the control system dynamically adjusts the working parameters of the static eliminator assembly according to the detection result, including the following steps: Compare the static electricity potential data transmitted by the detection component with a preset safety threshold; If the detection result is lower than the threshold, maintain the current working parameters; if it is higher than the threshold, dynamically adjust the output voltage of the high-voltage power supply according to the error value, and the adjustment range is from 5 kV to 15 kV; Dynamically adjust the generation ratio of positive and negative ions and the pulse discharge frequency according to the nature of static electricity; Detect the static electricity potential again after adjustment and feedback it to the control system until the static electricity potential of the yarn reaches the safe range.

[0015] The beneficial effects of the present invention are as follows: By ionizing positive and negative ions in the air through the static electricity elimination component, the present invention quickly and efficiently neutralizes the static electricity on the surface of the yarn. Combining with the humidifying component to adjust the surface humidity of the yarn, it further reduces the static electricity accumulation, and fundamentally avoids problems such as yarn entanglement, adhesion, and equipment failure caused by static electricity; The detection component can real-time monitor the static electricity potential on the surface of the yarn, and dynamically adjust the working parameters of the static electricity elimination component through the control system, realizing precise adaptability to different processing conditions and environments; A set of full-process and integrated static electricity treatment system is constructed to ensure the stable operation of the yarn during transportation and processing, and effectively improves the stability and consistency of the processing technology. Description of the Drawings

[0016] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for the description of the embodiments or the prior art. Obviously, the drawings in the following description are only some embodiments recorded in the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0017] Figure 1 It is the step flow chart of the method for removing static electricity from the pre-oxidized yarn in the embodiment of the present invention; Figure 2 It is the structural schematic diagram of the method for removing static electricity from the pre-oxidized yarn in the embodiment of the present invention.

[0018] Reference numerals: 1, guiding component; 2, humidifying component; 3, static electricity elimination component; 4, detection component. Detailed Embodiments

[0019] The following will clearly and completely describe the technical solutions in the embodiments of the present invention with reference to the drawings in the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, rather than all embodiments.

[0020] As Figures 1 to 2 shown, a method for removing static electricity from pre-oxidized yarn includes the following steps: Guide the PAN yarn through the guiding component, and make the yarn run along the set conveying path; Use the driving component to drive the guiding component, so that the yarn runs along the conveying path at a set speed; Use the humidifying component to adjust the surface humidity of the yarn to reduce static electricity accumulation; Ionize positive and negative ions in the air through the static eliminator component to neutralize the static electricity on the yarn surface; Use the detection component to detect the static electricity potential on the yarn surface and transmit the detection result to the control system; The control system dynamically adjusts the working parameters of the static eliminator component according to the detection result; Guide the static electricity-treated yarn to the outlet.

[0021] As Figure 2 shown, when the PAN yarn passes through the static eliminator device, use the guiding component to change the conveying direction of the yarn. The yarn with static electricity first passes through the humidifying component, and use the water vapor sprayed out in the humidifying component to increase the humidity around the yarn and reduce the static electricity potential; then pass through the static eliminator component to corona the air to generate positive and negative ions, and neutralize the static electricity on the yarn through the diffusion of positive and negative ions in the air; finally, before the yarn is wound up, detect the potential on the yarn, and adjust the parameters of the static eliminator component through the potential value to make the static electricity elimination more efficient. It should be pointed out here that there are many forms of the humidifying component, which can be spray humidification, steam humidification, water bath humidification or other structural forms. It should also be pointed out that there are many forms of the static eliminator component, which can be ion blowers, static bars, static elimination nets or high-voltage ionization devices, etc. It should also be pointed out that there are many forms of the detection component, which can be potential measurement probes, static electricity potential sensors or other structural forms such as non-contact detection devices.

[0022] The present invention ionizes positive and negative ions in the air through the static eliminator component to quickly and efficiently neutralize the static electricity on the yarn surface, combines the humidifying component to adjust the surface humidity of the yarn, further reduces static electricity accumulation, and fundamentally avoids problems such as yarn entanglement, adhesion and equipment failure caused by static electricity; the detection component can real-time monitor the static electricity potential on the yarn surface, and dynamically adjust the working parameters of the static eliminator component through the control system to achieve precise adaptability to different processing conditions and environments; constructs a full-process and integrated static electricity treatment system to ensure the stable operation of the yarn during conveying and processing, and effectively improves the stability and consistency of the processing technology.

[0023] In some embodiments of the present invention, to make the surface of the yarn moderately moist, the humidifying component adjusts the humidity of the yarn surface by spraying water mist with a particle size range of 10 μm to 50 μm. By spraying water mist with a particle size of 10 μm to 50 μm to adjust the humidity of the yarn surface, a uniform and efficient humidifying effect can be achieved, effectively reducing the surface resistance of the yarn, reducing static electricity accumulation, and providing a good foundation for static electricity neutralization; the water mist within this particle size range avoids the problems of excessive surface wetness of the yarn caused by too large a particle size or too fast water evaporation caused by too small a particle size, ensuring that the yarn is moderately moist, thereby maintaining the processing performance and quality of the yarn. In addition, the water mist within this range is suitable for a variety of yarn materials, meeting the humidity adjustment requirements of different materials and not damaging the surface characteristics of the yarn.

[0024] In some embodiments of the present invention, the static electricity eliminating component includes a DC high-voltage power generator, a discharge electrode, and a static electricity bar. The static electricity bar is installed at a position no more than 300 mm away from the yarn surface, and three yarns pass through the length range of the static electricity bar simultaneously. The length design of the static electricity bar can cover three yarns simultaneously, improving the parallel processing ability and production efficiency of the yarn, reducing the complexity of equipment adjustment and installation, and meeting the requirements of synchronous processing of multiple yarns.

[0025] There are many neutralization methods for the static electricity eliminating component. In some embodiments of the present invention, the static electricity eliminating component ionizes positive and negative ions in the air to neutralize the static electricity on the yarn surface, and further includes the following steps: Applying a high voltage to the tip of the discharge electrode through a power generator to generate corona discharge; Ionizing the air into a large number of positive and negative ions; Using the positive and negative ions diffused in the air to neutralize the static electricity on the yarn surface.

[0026] Applying a high voltage to the tip of the discharge electrode through a power generator to generate corona discharge, ionizing the air into a large number of positive and negative ions, and using the positive and negative ions diffused in the air to neutralize the static electricity on the yarn surface can quickly and effectively eliminate the accumulation of static electricity on the yarn surface, avoiding problems such as yarn entanglement, adhesion, and equipment failure caused by static electricity. This method uses a non-contact static electricity neutralization method, avoiding mechanical damage to the yarn surface caused by direct contact, and at the same time can cover multiple yarns, ensuring the uniformity and efficiency of static electricity treatment. In addition, using positive and negative ions generated by air ionization to eliminate static electricity not only has simple operation and stable operation, but also has the advantages of wide applicability and environmental protection, significantly improving the quality and production efficiency of yarn processing.

[0027] When the yarn passes through the device of the present invention, the passing speed also affects the generation of static electricity on the surface of the yarn. In some embodiments of the present invention, the yarn runs along the conveying path at a speed of 10 m / min to 50 m / min. The speed of the yarn can take into account both the stable conveying of the yarn and the processing efficiency, and is suitable for different production requirements; this speed range can avoid the problems of increased surface friction of the yarn and excessive static electricity accumulation caused by too fast running speed, and can also avoid the influence of too slow running speed on production efficiency, thus achieving a good balance between the conveying speed and static electricity control; on the one hand, it can provide sufficient processing time for subsequent humidification treatment and static electricity neutralization. On the other hand, it can reduce the static electricity generated by the friction between the yarn and the guiding component, ensure the stability and uniformity of the surface humidity and static electricity control effect of the yarn, and effectively improve the processing quality and the overall operation efficiency of the production line.

[0028] The friction between the surface of the guiding component and the yarn will also generate static electricity. To inhibit the generation of static electricity, the surface of the guiding component is coated with a ceramic layer. The surface is coated with a ceramic layer, which can significantly improve its wear resistance and smoothness, reduce the friction coefficient between the yarn and the surface of the guiding component during operation, and reduce the static electricity accumulation generated by the friction of the yarn; compared with other metal materials, ceramics have poor electrical conductivity and thermal conductivity, are not easy to release charges, and are not easy to conduct electricity. The chrome-plated roller is to deposit a chromium layer on the surface of the roller body, which can improve the hardness and wear resistance of the roller body, but its antistatic performance is poor, and static electricity is likely to accumulate on the surface of the chrome-plated roller, thus causing static electricity discharge phenomena. The sprayed ceramic roller is to spray a ceramic coating on the surface of the roller body. The ceramic coating has good insulation performance. When the pre-oxidized yarn contacts and rubs against the ceramic roller, it can effectively prevent the generation and accumulation of static electricity, thereby improving the antistatic ability of the roller body and further reducing the possibility of static electricity generation.

[0029] By adjusting the diameter of the guiding component to be larger than that of other guiding rollers, and using the principle that the larger the diameter, the slower the rotation speed. In some embodiments of the present invention, the diameter range of the guiding component is 150 mm - 200 mm. When the movement speed of the guiding component slows down, the friction and separation speed will also decrease accordingly, thereby reducing the generation of static electricity. Therefore, increasing the diameter of the guiding roller can indirectly reduce the rotation speed of the guiding component. Let the initial diameter of the guiding roller be D 1 , the winding line speed be V, and the rotation speed of the guiding roller be N 1 , then N 1 = V / πD 1 , the increased diameter of the guiding roller be D 2 , the rotation speed of the guiding roller be N 2 , then N 2 = V / πD 2 , since D 2 > D 1 , then N 2 < N 1, it can be seen that by increasing the diameter of the guide roller, the rotation speed of the guide roller can be reduced, thereby reducing the possibility of static electricity generation when the pre-oxidized yarn rubs against the guide roller.

[0030] In some embodiments of the present invention, the detection component is a non-contact static electricity potential sensor, and the detection range is from -10 kV to +10 kV. It can achieve accurate real-time monitoring of the static electricity potential on the surface of the yarn, avoid damage to the yarn surface caused by contact detection, and at the same time ensure the stability and continuity of measurement. Its wide detection range can cover various static electricity accumulation situations that may occur during the yarn processing process. Whether it is high-potential or low-potential static electricity, it can accurately capture it to ensure the timeliness and effectiveness of static electricity neutralization treatment.

[0031] In some embodiments of the present invention, using the detection component to detect the static electricity potential on the surface of the yarn and transmitting the detection result to the control system includes the following steps: Set a non-contact static electricity potential sensor as the detection component for detecting the static electricity potential on the surface of the yarn; The detection component collects static electricity potential data in real time during the operation of the yarn, and the collection frequency is from 10 Hz to 100 Hz; Transmit the collected static electricity potential data to the control system through the data transmission module; The control system compares the received static electricity potential data with the preset static electricity potential safety threshold; If the static electricity potential is lower than the preset threshold, maintain the working parameters of the current static electricity removal component; If the static electricity potential is higher than the preset threshold, calculate the error value and dynamically adjust the working parameters of the static electricity removal component to reduce the static electricity potential on the surface of the yarn.

[0032] By using the detection component to detect the static electricity potential on the surface of the yarn and transmitting the detection result to the control system, real-time monitoring and dynamic adjustment of the static electricity potential can be achieved; the non-contact static electricity potential sensor collects static electricity data on the surface of the yarn in real time at a collection frequency of 10 Hz to 100 Hz, ensuring high frequency and high accuracy of detection and avoiding abnormal accumulation of static electricity caused by low sampling rate; the detection component transmits the static electricity potential data to the control system through the data transmission module, and the control system can compare the collected data with the preset safety threshold to dynamically judge the static electricity level; if the static electricity potential exceeds the safety threshold, the control system calculates the error value in time and adjusts the working parameters of the static electricity removal component to ensure that the static electricity of the yarn is quickly and effectively neutralized; this closed-loop control system not only improves the accuracy and adaptability of static electricity neutralization, but also can avoid yarn entanglement, adhesion and equipment failures caused by excessive static electricity, ensuring the stable operation of the production line and the quality of yarn processing, and at the same time improving the intelligence and automation level of the equipment.

[0033] In some embodiments of the present invention, the control system dynamically adjusts the operating parameters of the static elimination component according to the detection results, including the following steps: Compare the static potential data transmitted by the detection component with a preset safety threshold; If the detection result is lower than the threshold, maintain the current operating parameters; if it is higher than the threshold, dynamically adjust the output voltage of the high-voltage power supply according to the error value, and the adjustment range is 5 kV to 15 kV; Dynamically adjust the generation ratio of positive and negative ions and the pulse discharge frequency according to the nature of the static electricity; Detect the static potential again after adjustment and feedback it to the control system until the static potential of the yarn reaches the safe range.

[0034] The control system dynamically adjusts the operating parameters of the static elimination component according to the detection results. By comparing the static potential data with the preset safety threshold, precise control of the static electricity neutralization process is achieved. When the detection result is lower than the threshold, the system maintains the current operating parameters, avoiding unnecessary adjustments and improving energy efficiency utilization; when the detection result is higher than the threshold, the system dynamically adjusts the output voltage of the high-voltage power supply according to the error value and dynamically adjusts the generation ratio of positive and negative ions and the pulse discharge frequency according to the static electricity nature of the yarn to ensure the pertinence and effectiveness of static electricity neutralization. In addition, the system detects the static potential again after adjustment and gives feedback to form a closed-loop control until the static potential of the yarn reaches the safe range. This dynamic adjustment method can quickly respond to changes in the static electricity level, precisely neutralize the static electricity on the surface of the yarn, avoid quality problems and equipment failures caused by excessive static electricity, improve the efficiency of static electricity control and the stability of yarn processing, and at the same time enhance the intelligence level and energy-saving effect of the equipment.

[0035] In the description of the present invention, the terms "first" and "second" are only used for descriptive purposes and cannot be understood as indicating or implying relative importance or implicitly specifying the quantity of the indicated technical features. Thus, the features defined with "first" and "second" may explicitly or implicitly include one or more of such features. The meaning of "plural" is two or more unless otherwise specifically defined.

[0036] In the present invention, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected to", "fixed" and other terms should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or integrated; it can be a mechanical connection or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium, and it can be the internal communication of two components or the interaction relationship between two components. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0037] In the description of this specification, the description referring to terms such as "one embodiment", "some embodiments", "examples", "specific examples", or "some examples" etc. means that the specific features, structures, materials, or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials, or characteristics described may be combined in any one or more embodiments or examples in a suitable manner. In addition, without contradiction, those skilled in the art can combine and combine the different embodiments or examples described in this specification and the features of different embodiments or examples.

[0038] Any process or method description shown in a flowchart or described in other ways herein can be understood to represent a module, segment, or portion of code including one or more executable instructions for implementing a specific logical function or process, and the scope of the preferred embodiments of the present invention includes additional implementations, where the functions may be executed in a substantially simultaneous manner or in a reverse order according to the functions involved, rather than in the order shown or discussed, which should be understood by those skilled in the art to which the embodiments of the present invention pertain.

Claims

1. A method for removing static electricity from pre-oxidized silk yarn, characterized in that: The steps include: Passing the preoxidized yarn through the guide assembly to guide the yarn to run along a set conveying path; Using a driving assembly to drive the guide assembly so that the yarn runs along the conveying path at a set speed; Use humidification components to adjust the humidity on the yarn surface to reduce static electricity accumulation; The static electricity on the yarn surface is neutralized by ionizing the positive and negative ions in the air through the static electricity elimination component; Using the detection component to detect the electrostatic potential on the yarn surface, and transmitting the detection result to the control system; The control system dynamically adjusts the working parameters of the static elimination component according to the detection results; The electrostatically treated yarn is guided to the outlet.

2. The method for removing static electricity from preoxidized silk yarn according to claim 1, characterized in that: The humidifying component adjusts the surface humidity of the yarn by spraying water mist, and the particle size of the water mist ranges from 10 μm to 50 μm.

3. The method for removing static electricity from preoxidized silk yarn according to claim 1, characterized in that: The static elimination component includes a DC high-voltage power generator, a discharge electrode and an electrostatic rod. The electrostatic rod is installed at a distance of no more than 300 mm from the yarn surface, and three yarns pass through the length of the electrostatic rod at the same time.

4. The method for removing static electricity from preoxidized silk yarn according to claim 3, characterized in that: The static elimination component ionizes positive and negative ions in the air to neutralize the static electricity on the surface of the yarn, and also includes the following steps: Applying high voltage to the tip of the discharge electrode through a power generator to generate corona discharge; Ionize the air into a large number of positive and negative ions; The positive and negative ions diffused in the air are used to neutralize the static electricity on the surface of the yarn.

5. The method for removing static electricity from preoxidized silk yarn according to claim 1, characterized in that: The yarn runs along the conveying path at a speed of 10 m / min to 50 m / min.

6. The method for removing static electricity from preoxidized silk yarn according to claim 1, characterized in that: The surface of the guide component is coated with a ceramic layer.

7. The method for removing static electricity from preoxidized silk yarn according to claim 1, characterized in that: The guide assembly has a diameter ranging from 150 mm to 200 mm.

8. The method for removing static electricity from preoxidized silk yarn according to claim 1, characterized in that: The detection component is a non-contact electrostatic potential sensor with a detection range of -10kV to +10kV.

9. The method for removing static electricity from preoxidized silk yarn according to claim 1, characterized in that: The method of using the detection component to detect the electrostatic potential on the surface of the yarn and transmitting the detection result to the control system includes the following steps: A non-contact electrostatic potential sensor is provided as a detection component for detecting the electrostatic potential on the surface of the yarn; The detection component collects electrostatic potential data in real time during the yarn running process, with a collection frequency of 10Hz to 100Hz; The collected electrostatic potential data is transmitted to the control system through the data transmission module; The control system compares the received electrostatic potential data with a preset electrostatic potential safety threshold; If the electrostatic potential is lower than a preset threshold, the current working parameters of the static electricity removal component are maintained; If the electrostatic potential is higher than a preset threshold, an error value is calculated and the working parameters of the static removal component are dynamically adjusted to reduce the electrostatic potential on the yarn surface.

10. The method for removing static electricity from preoxidized silk yarn according to claim 9, characterized in that: The control system dynamically adjusts the working parameters of the static elimination component according to the detection results, including the following steps: comparing the electrostatic potential data transmitted by the detection component with a preset safety threshold; If the detection result is lower than the threshold, the current working parameters are maintained; if it is higher than the threshold, the output voltage of the high-voltage power supply is dynamically adjusted according to the error value, and the adjustment range is 5kV to 15kV; Dynamically adjust the generation ratio of positive and negative ions and the pulse discharge frequency according to the electrostatic properties; After the adjustment, the electrostatic potential is detected again and fed back to the control system until the yarn electrostatic potential reaches a safe range.

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