124 results about "Cable ampacity" patented technology

The invention relates to an identification method of cable current-carrying capacity and an identification device; after relative performance parameters of the cable are measured, the temperature endvalue of the conductor is calculated by setting current initial value of the conductor and the temperature initial value of the conductor, and the temperature initial value of a conductor is correctedaccording to the difference of the temperature end value and the temperature initial value of the conductor, until the difference of the two-time conductor temperature is less than a first presettingdeviation range, at the moment, the temperature end value of the conductor is the conductor temperature under the action of the current initial value of the present conductor; the current initial value of the conductor is continuously corrected according to the difference of the temperature end value of the conductor and 90 (the highest insulating working temperature of XLPE), until the absolutedifference of the temperature end value of the conductor and 90 is less than a second deviation range, the current initial value of the conductor, corresponding to the end value of the conductor temperature, is determined into the final cable current-carrying capacity. By initializing the value of the conductor current and temperature and adopting an iteration process which is continuously carriedout, the problem that the obtained result in the existing method is inaccurate, so as to determine the cable current-carrying capacity accurately.

The invention relates to a method and a system for monitoring current-carrying capacity of a cable based on a distributed optical fiber temperature measuring method. The system comprises a laser drive device which is matched with a temperature sensing device in a cable; the temperature sensing device is matched with the corresponding optical fiber splitter; the output end of each optical fiber splitter is connected with one end of the cable; the other end of the cable is connected with a wire distribution cabinet which is matched with demodulating equipment; and the output end of the demodulating equipment is connected with a cable integrated Ethernet chip (IEC) compute server which is output to a client terminal. Combining the distributed optical fiber temperature measuring method, by the method and system provided by the invention, the important parameters of the cable operation can be acquired; the stimulated accuracy is greatly improved through the comprehensive analysis of the current-carrying capacity, thus providing the decision standard for ensuring the safe operation of the city cables and the reasonable configuration of the transmission capacity.

The invention provides a silane crosslinked low retraction polyethylene plastic and an application of the same, the components and parts by weight include 100 parts of polyethylene resin, 0.01-3 parts of weather resistant additive, 0.1-20 parts of metal oxide, 0.01-10 parts of color master batch, 0.5-3 parts of silane crosslinked agent, 0.01-1.5 parts of initiator, 0.02-2 parts of antioxidant, 0.05-1 parts of metal passivator and 0.01-5 parts of catalyst. The invention can produce silane crosslinked polyethylene insulating plastics with various colors meeting the weather resistant requires for overhead cable, in particular, the grey product can decrease the acceptance degree of environmental thermal radiation of the cable, increase the current carrying capacity of the overhead cable and meet various needs of different levels of the overhead cable.

The invention discloses an ANSYS-based crosslinking polyethylene insulated cable temperature field finite element calculation method. The method successively comprises the following steps: firstly, taking a crosslinking polyethylene insulated cable as a research object and performing parametric geometric modeling based on a simulation software ANSYS, secondly, applying current excitation to the crosslinking polyethylene insulated cable to perform magnetic field analysis, applying voltage excitation to the crosslinking polyethylene insulated cable to perform electric field analysis then, and simultaneously loading joule heat loss, eddy-current loss and medium loss obtained from the magnetic field analysis and the electric field analysis to the crosslinking polyethylene insulated cable to be taken as heat sources, perform temperature field analysis and perform calculation of a crosslinking polyethylene insulated cable temperature field. The method has great flexibility and adaptability of solving for complex regional and border problems, can more accurately calculate the temperature of a crosslinking polyethylene insulated cable conductor, and then can explore the potential of cable current carrying capability; and the method can save cable investment, and also can improve the cable utilization rate and cable operating level.

The invention discloses a concept of combined insulation of a cable, and provides a method for determining the combined insulation thermal resistance of the cable. The combined insulation of the cable comprises every layer between a conductor and a metallic sheath, namely the layers between the conductor and the metallic sheath are regarded as a whole body, different constant current values are applied to the cable in a laying test, and a recommended value for the combined insulation thermal resistance of the cable is determined by combining a constant current value, a resistance value of the conductor and the like according to a conductor temperature value and a metallic sheath temperature value measured under a condition with different constant current values, wherein the recommended value for the combined insulation thermal resistance of the cable is a parameter value obtained by comprehensively considering materials of each layer between the conductor and the metallic sheath, so the recommended value is closer to the actual condition of the insulation thermal resistance of the cable, and the obtained current-carrying capacity of the cable is more accurate when the current-carrying capacity of the cable is deduced and calculated according to the recommended value for the combined insulation thermal resistance of the cable.

The invention belongs to the technical field of Internet of Things, relates to a comprehensive pipe rack online monitoring system and method, and solves technical problems in the prior art that the design is not reasonable and the like. The system comprises a control center, a plurality of area control units and an optical fiber ring network. The control center and the area control units are connected on the optical fiber ring network. Each area control unit is connected with a pipe rack environment monitor subsystem, a video monitor subsystem, an emergency communication subsystem, a staff positioning subsystem, an invasion monitoring subsystem, a fire-fighting alarm subsystem, an electronic patrol subsystem and a high voltage cable body detection subsystem. The high voltage cable body detection subsystem comprises a cable temperature monitoring unit, a cable partial discharge monitoring unit, a cable sheath circulation monitoring unit and a cable current-carrying capacity monitoring unit. The design layout is reasonable, the function is comprehensive, the safety coefficient is high, comprehensive monitoring and centralized management are achieved, no monitoring device is required for each kind of pipelines, and the equipment cost is greatly lowered.

The invention discloses a power cable intermediate joint temperature calculating method, and belongs to the technical field of cable monitoring. The method comprises the following steps: A, consulting an IEC60287 standard, obtaining correlation parameters needed for calculating the current-carrying capacity of a cable, a current-carrying capacity load current value I3 of the load, a body skin temperature measuring value theta 2' of the cable, and an ambient temperature theta 0; B, obtaining a correction coefficient k, and obtaining a correction formula; C, according to correlation parameters, introducing the I3 into the correction formula, and inversely calculating a conductor temperature rise delta theta higher than the ambient temperature; D, according to the theta 2' and the delta theta, solving a body conductor temperature theta1' of the cable; and E, according to the ambient temperature theta 0 and the body conductor temperature theta 1', solving a joint skin temperature theta 2 and a joint conductor temperature theta 1 by use of a joint temperature calculation formula. According to the invention, the correction coefficient k is introduced so that the precision of calculating the current-carrying capacity of the cable by means of the IEC 60287 standard is improved. The intermediate joint temperature calculation method is also brought forward, and the method can accurately calculate the joint conductor temperature and the joint skin temperature, facilitates real-time monitoring of the intermediate joint and well supplements the IEC 60287 standard.

The invention discloses a method and device for determining the current-carrying capacity of a cable. The method comprises the following steps of: measuring the skin temperature of the cable and the environmental temperature at a preset distance away from the cable; according to the skin temperature and the environmental temperature, determining the current-carrying capacity of the cable. According to the scheme of the invention, through measuring the skin temperature of the cable and the environmental temperature at a preset distance away from the cable, and based on the measured skin temperature and the environmental temperature, the current-carrying capacity of the cable is determined, and the current-carrying capacity of the cable is estimated through fully considering the surrounding environment temperature of the cable, therefore, the error influence of environment changes on the current-carrying capacity of the cable is avoided, so that the obtained current-carrying capacity of the cable is smaller in error and more accurate.

The invention relates to an environment factor monitoring and finite element-based underground power cable current-carrying capacity online prediction system and an environment factor monitoring and finite element-based underground power cable current-carrying capacity online prediction method. The system consists of a temperature sensor used for measuring the air temperature, a wind speed sensor, a humidity sensor, a singlechip system and a scheduling host of a power department. The method comprises the step of predicting the current-carrying capacity of an underground power cable by combining temperature, wind speed, humidity and other data measured in real time with the calculation of a finite element temperature field. The system and the method have the advantages that: the system and the method can accurately predict the current-carrying capacity of the underground power cable on line, so that the power department can develop the capacity of conveying electric energy to the greatest degree; meanwhile, the system and the method can avoid the resource waste phenomenon of wasting the talent on a petty job on the premise of guaranteeing safe and reliable operation.

The invention discloses an optical fiber composite power seabed oil-filled cable, which is characterized in that a light unit layer is arranged in a defending layer. The light unit layer is twisted by an optical fiber and polyethylene filled bar at interval. A metal protecting layer comprises a lead protecting layer, wherein a return feeder layer is arranged outside the lead protecting layer. The return feeder layer is assembled by a flat copper line. A lining layer is arranged between the lead protecting layer and the return feeder layer. The return feeder layer is arranged in the metal protecting layer so as to improve the short circuit current of the metal protecting layer and help to improve the current carrying amount of the cable at the same time. The invention has the advantages of higher electrical performance and sufficient mechanical intensity by combining the seabed optical fiber cable and seabed power cable.

The invention belongs to the technical field of cable temperature measurement, and particularly relates to a cable conductor temperature measurement system based on an acoustic surface wave temperature sensor and an algorithm thereof. The measurement system comprises the acoustic surface wave temperature sensor, a data transmission system and a cable temperature monitoring system. The acoustic surface wave temperature sensor is configured on the surface of a cable joint and the surface of a cable body. Acquired data are transmitted to a cable temperature monitoring system through the data transmission system. Furthermore according to the measured surface temperature of the cable and a theoretical calculation method for cable current-carrying capacity, conductor temperature is calculated through the surface temperature and a cable structure parameter, thereby realizing real-time monitoring on the temperature of a cable conductor. The cable conductor temperature measurement system settles a problem of relatively high difference between the conductor temperature at the cable joint and the conductor temperature at the body caused by complicated structure at the middle joint of the cable and adverse environment, thereby realizing temperature measurement on the cable joint conductor, and greatly improving convenience and accuracy in conductor temperature measurement.

The invention provides a method and a system for determining the current-carrying capacity of a three-core cable laid in a cable duct. The method comprises the following steps: acquiring related parameters of the cable duct; determining integrated environment temperature and cable duct temperature rise; determining cable duct temperature according to the integrated environment temperature and the cable duct temperature rise; correcting thermal resistance of media around the cable in unit length according to the cable duct temperature; and determining the current-carrying capacity of the cable according to the corrected thermal resistance of the media around the cable in the unit length and the related parameters of the cable. The method and the system effectively solve a problem that the current-carrying capacity of the cable in the cable duct is calculated to be obviously high in the prior art, and can accurately determine the current-carrying capacity of the cable laid in the cable duct.

The invention discloses a steady-state iteration measuring method for the current-carrying capacity of a cable. The method includes the first step of measuring the skin temperature of the cable and the environment temperature of the cable, and the second step of obtaining initial cable environment thermal resistance according to the skin temperature of the cable and the environment temperature of the cable and calculating the current-carrying capacity of the cable in an iteration method. According to the steady-state iteration measuring method for the current-carrying capacity of the cable, the skin temperature of the cable and the environment temperature of the cable are measured, the current-carrying capacity of the cable is calculated according to the measured skin temperature of the cable and the measured environment temperature of the cable in the iteration method, and calculation of the thermal resistance is referred to when the current-carrying capacity of the cable is calculated; the thermal resistance includes cable internal thermal resistance and environment thermal resistance, and the environment thermal resistance changes along with the change of the cable load; the change of the environment thermal resistance is taken into account in the iteration method so that a calculation error of the current-carrying capacity of the cable can be smaller.

The invention discloses a monitoring device and a monitoring method for the current capacity of a maritime platform cable. The monitoring device comprises a power distribution cabinet, an optical-fiber grating demodulation monitoring system, a current acquisition device, transmission and relay equipment and a temperature sensor, wherein the current acquisition device is connected with the power distribution cabinet to be used for transmitting the current which is collected by the current acquisition device into the transmission and relay equipment, and an electrical signal is converted into a light signal through the transmission and relay equipment; the temperature sensor is laid on the surface of a cable, and tail fibers of the temperature sensor are gathered into an optical fiber distribution box to be connected into the optical-fiber grating demodulation monitoring system by the optical fiber distribution box through an optical cable. The monitoring method adopts the following steps of 1, collecting real-time current; 2, collecting real-time temperature; 3, carrying out calculation on the temperature and the current capacity of a conductive wire core; 4, carrying out judgment on monitoring data. According to the monitoring device and the monitoring method, dispatch and adjustment on the load of the cable can be carried out, safety in operation of the cable is guaranteed, the problem of power supply in an emergency status is solved, and reasonable utilization of the cable is realized.

The invention relates to a cable ampacity analysis system based on a linear temperature-sensitive technology and a calculation method for cable ampacity. The cable ampacity analysis system comprises a server, as well as a distribution type linear temperature-sensitive system and a cable load detector, which are connected with the server, wherein the distribution type linear temperature-sensitive system is formed by a temperature-sensitive optical cable laid on a cable to be detected, a wavelength-adjustable laser and a light intensity detector, and the wavelength-adjustable laser and the light intensity detector are connected with the temperature-sensitive optical cable. According to the invention, via adding a dynamic time variable, correspondence relationship among cable electric flux, surface temperature of a cable outer protective sleeve, cable environmental temperature and cable heat radiation during the operation of the cable is established, and the temperature of a conductor of the cable is calculated, as a result, the analysis system and the calculation method provide a decision basis for ensuring safe operation of cables in cities and reasonably deploying power transmission capacity, supply a scientific basis to scientific load dispatch, and have import significance.

The invention discloses a cable low heat resistance protection medium with high water content, high stability, low heat resistance, environment protection and effective prevention of termite damage, and a preparation method thereof. The filling medium is prepared by mixing bentonite, fine quartz sand, water and cement, and using a small amount of tartaric acid and sodium sesquicarbonate as additives. As accounted by 100% of mass fraction, the filling medium is preferably prepared by 54%-57% of bentonite, 24%-28% of fine quartz sand, 14%-16% of water, 2.5-3.5% of cement, 0.24%-0.26% of tartaric acid and 0.24%-0.26% of sodium sesquicarbonate. Before condensation, the filling medium has the advantages of better initial liquidity, moderate alkalinity, low bleeding rate and the like. After condensation, compared with traditional material, the filling medium has the advantages of high water content and high stability, and enables the surroundings of the cable to maintain low heat resistance for long term, the heat resistance is smaller than that of soil, and the hardness is higher, therefore the current carrying amount of the cable is improved, or the running temperature of the cable conductor is reduced.

The invention provides a real-time dynamic calculation method and system for cable carrying capacity. The method comprises steps as follows: load current with a preset load value is input into a cable, and a first surface temperature value of the cable as well as an air temperature value, a wind power value and a solar radiation value of the soil surface is collected; iterative processing is performed on a preset first soil heat conductivity coefficient with a data iterative algorithm according to the values, a second soil heat conductivity coefficient is obtained, and an equivalent thermal resistance coefficient of soil is obtained; the soil is subjected to layering treatment, a layered soil model is established, external heat resistance of the soil is obtained through equivalent thermal resistance coefficient treatment; a cable body thermal circuit model is established according to scheduled rules, and the cable carrying capacity of the cable is obtained according to the cable body thermal circuit model and soil external heat resistance treatment. The method and the system have the beneficial effects as follows: a soil water migration based layered soil model analysis method and a numerical iteration analysis method are introduced into the cable thermal circuit model, so that the cable carrying capacity is calculated more accurately.

The invention discloses a reinforced cable core and a manufacturing method thereof. The reinforced cable core comprises a fiber reinforced core and a metallic sheath, wherein the fiber reinforced core is coated by the metallic sheath. The reinforced cable core of the invention not only has the advantages of low density, low expansion coefficient, high tensile strength and the like, but also has the functions of improving the current carrying capacity of a cable, shielding an inner fiber composite structure to avoid the electrical erosion between a fiber and an aluminum conductor, protecting the surface of a fiber composite material and reducing the mechanical performance loss caused by surface damage. Compared with reinforced cable cores with other structures, which are formed by only fiber composite cores, the reinforced cable core of the invention not only plays a role of bearing but also can further improve the current carrying capacity of the cable.

The invention discloses a buried cable current carrying capacity calculation method. The method comprises the following steps that S1, a two-dimensional temperature field model of a buried cable is established, and a geometrical model of the buried cable is established according to cable arrangement in the two-dimensional temperature field model and environmental parameters; S2, physical property parameters of soil around the buried cable are determined; S3, the scope and boundary conditions of the two-dimensional temperature field model of the buried cable are determined; S4, the buried cable is subjected to grid division, and the minimum grid unit size and the maximum grid unit size which are matched with the geometrical model of the buried cable are set; S5, the calculation method of two-dimensional temperature field distribution of the buried cable is determined, and a corresponding solver is configured; S6, calculation is conducted to obtain two-dimensional temperature field distribution of the buried cable, and consequently the steady-state current carrying capacity of the buried cable is obtained. Based on a finite element method, the current carrying capacity value of the cable is obtained by establishing a current carrying capacity calculation model of the buried cable and simulating actual heat exchange boundary conditions.

An improvement of three cores high voltage lifting cable of high-rise building is adopting single core insulating cables and between them filled by three carrying steel cores with insulating coat of arc sector section. They cross into cable and outside is pricked by high-intensity strap. The arc sector bearing touches with closed cable core with large acreage and this enhances the friction of them greatly. For the crossing and strap, it increases the friction between them and greatly enhances the whole tensile strength of cable to endure more strength and is suit for lifting 150 meters or higher construction. It also increases current capacity of cable about 10-30% and reduces the weight of cable about 20-30% to cut down the cost. The arc sector bearing gives more little side pressure to cable and the cable is safe with good reliability. The absolute structure of three cores bearing reduces the difficulty of production.

The invention relates to a real-time on-line monitoring device for monitoring the abnormal operation of a switch cabinet. The device comprises a partial discharge monitor, a load current device and a temperature sensor, wherein the partial discharge monitor is arranged on the surface of a shell of the switch cabinet and is used for acquiring transient state earth electrical signals in the switch cabinet; after being converted by photoelectricity, the electrical signals are transmitted into an industrial personal computer; the load current device is arranged in the switch cabinet, is connected with a current transformer arranged in the switch cabinet, and is used for carrying out photovoltaic conversion on the numerical value of the acquired real-time load current, transmitting optical signals into the industrial personal computer and monitoring the calculated real-time current-carrying capacity of a cable; the temperature sensor is arranged at a movable contact of a circuit breaker in the switch cabinet, and is used for monitoring the contact temperature in an on-line way and sending the acquired temperature signals into the industrial personal computer. The real-time on-line monitoring device can be used for carrying out real-time comprehensive on-line monitoring on the partial discharge, the temperature change and the current-carrying capacity of the cable in the switch cabinet, and can eliminate or find failure and hidden danger in time by monitoring the safe running condition of the switch cabinet in an on-line way.

The invention discloses an online monitoring system for carrying capacity of a cable, belonging to the technical field of electrical equipment. The online monitoring system comprises an optical fiber grating temperature sensor, a load current collector and a micro processor, wherein the optical fiber grating temperature sensor is used for monitoring the ambient temperature of the outer skin of the cable and the cable in real time; the load current collector is used for monitoring the cable load current in real time; and the micro processor is used for receiving the temperature information monitored by the optical fiber grating temperature sensor, and the current magnitude information collected by the load current collector, and acquiring the carrying capacity of the cable by combining structure parameters and the arrangement state of the cable, wherein the load current collector is connected with the micro processor by a photoelectric converter; and the optical fiber grating temperature sensor is connected with the micro processor. The online monitoring system achieves real-time monitoring on the cable current, can acquire the current residual carrying capacity of the cable in real time, and can randomly expand according to the requirements, so that overload and light-load of the cable can be effectively avoided to improve the utilization efficiency of the cable and guarantee the stable operation of the circuit.

The invention discloses a cable current-carrying capacity calculation method based on a finite element. Finite element simulation software is used for modeling, and through calculating simulation cable thermal field distribution, current-carrying capacity of a corresponding cross-section cable under demand environmental conditions. The steps comprise: a, setting and / or selecting a required simulation model module; b, according to actual dimensions of a cable, establishing a simulation model; c, setting solution domains of the cable and the environment where the cable is located; d, setting a boundary condition; e, meshing; f, setting solution; g, solving and calculating whether temperature of a conductor reaches maximum allowable temperature in continuous working; h, if a conclusion of the step g is yes, simulation ending, current at the maximum allowable temperature being cable current-carrying capacity; if the conclusion is no, changing a current value of the conductor, repeating step e to step g, until the conclusion is yes. The method accurately responds state of cable current-carrying capacity, and provides foundation for design and research of cable laying.

The invention provides an aerial insulated cable cross linked polyethylene insulation material containing graphene and a cable and aims to achieve the effect of reducing the loss of transmitted electric energy. The aerial insulated cable cross linked polyethylene insulation material contains, by mass, 80-90 parts of low density polyethylene, 10-20 parts of linear low density polyethylene, 0.05-3.5 parts of a heat conduction agent, 1-5 parts of an assisting heat conduction agent, 0.5-3 parts of a silane coupling agent, 0.11-0.21 part of an antioxidant, 0.03-0.15 part of a plasticizer, and 0.03-0.15 part of an initiator. The aerial insulated cable is characterized in that an insulation layer is made of the aerial insulated cable cross linked polyethylene insulation material containing graphene. Through the combination of the heat conduction agent and the assisting heat conduction agent, the heat conductivity of the insulation layer material can be remarkably increased, so that the loss of transmitted electric energy can be reduced or the cable carrying capacity can be increased, the ultraviolet ray resistance and the weather resistance are improved and the service life of the insulation layer of the aerial insulated cable is prolonged.

The invention provides a method and a system for determining a thermal parameter of a single-core cable conductor. The method comprises the following steps: layer equivalent insulating layers by taking a conductor shielding layer, an insulating layer and an insulating and shielding layer of the single-core cable conductor as the equivalent insulating layers, respectively establishing an infinitesimal cylinder wall transient thermal circuit model of each equivalent insulating layer and infinitesimal cylinder wall transient thermal circuit models of other layers of the single-core cable; and connecting the infinitesimal cylinder wall transient thermal circuit models of the equivalent insulating layers and the other layers of the single-core cable in series according to a practical structure of the single-core cable to form an optimized transient thermal circuit model of the single-core cable, thus obtaining the thermal parameter of the single-core cable conductor according to the optimized transient thermal circuit model. The transient thermal circuit model of the single-core cable is optimized, the thermal parameter of the conductor can be solved by using the optimized transient thermal circuit model, the accuracy can be obviously improved, and a calculation error of carrying capacity of the cable can be reduced.

The invention relates to a method and system for predicting temperature of a high voltage cable conductor. The method includes that a coefficient matrix model for predicting the temperature of cable conductors is established through utilizing the given cable structure data and a transient thermal path model; the matrix is assigned by cyclic assignment when forming a coefficient matrix, and then the eigenvalues and eigenvectors of the matrix are evaluated after forming the coefficient matrix; an integral function model is established according to the eigenvalues and eigenvectors, and then the integral function model is integrated to obtain a conductor temperature prediction model; the current value of the high voltage cable conductor is tested, and then the predicted temperature of the conductor is obtained through integrating by utilizing the conductor temperature prediction model and the predict moments and the electric current. The technology of the method and system for predicting the temperature of the high voltage cable conductor have important guide function in improving the cable carrying capacity, which have the advantages of improving load rate, achieving the purpose of cable capacity increase on the premise of ensuring the life of the cable.

The invention provides a high-voltage cable metal sheath circulation model and a model establishing method, and belongs to the technical field of electric power. The objective of the invention is to based on a single-core high-voltage cable engineering crossing grounding mode, establish a high-voltage cable metal sheath circulation model and a model establishing method of a grounding current mathematical calculation model of a single-core cable under a crossing interconnection grounding mode. The method comprises steps of establishing an equivalent circuit of a transposition section loop of the cable metal sheath crossing interconnection; constructing an equivalent circuit which is equivalent to an actual system; according to a circuit principle, by use of a loop voltage method, listing and writing an equation set of the equivalent circuit; and finally, solving the magnitude of grounding current of each phase of the metal sheath. According to the invention, by applying the designed high-voltage cable metal sheath circulation model into the current electric power system, the current high-voltage current circulation problem can be efficiently solved, so the current carrying capacityof the cable is greatly improved; normal operation service lifetime of the cable is prolonged; and occurrence of the accident is reduced.

The invention provides a method and system for measuring cable load carrying capacity. The method comprises the steps that the air temperature and the temperature of a cable conductor in a cable pipeline are measured to obtain an air temperature measured value and a cable conductor temperature value; relevant parameters of a cable are obtained; the cable load carrying capacity is determined according to the air temperature measured value, the cable conductor temperature value and the relevant parameters of the cable; an average air temperature verification value in the cable pipeline is determined according to the cable load carrying capacity and the relevant parameters of the cable; an absolute value of a difference of the air temperature measured value and the average air temperature verification value is compared with a preset control error value, if the absolute value is smaller than the preset control error value, the cable carrying capacity is taken as final cable load carrying capacity; otherwise, the average air temperature verification value is taken as a new air temperature measured value, and the steps for determining the air temperature measured value are returned to. By the aid of the scheme, the cable load carrying capacity can be measured accurately, and the process is simple and convenient.

The invention relates to a heat-resistant control cable utilized by a nuclear power station. The heat-resistant control cable comprises a combined cable core and a coating. The combined cable core is formed by cable core wires according to a normal intertwisting mode; and the cable core wire comprises a core wire conductor and a double insulating layer, wherein the double insulating layer is wrapped at a peripheral portion of the core wire conductor. The coating is successively formed by a polyolefin filler, a polyester film separating layer, a shielding layer, a glass fiber flame retardant belt, a crosslinking polyethylene blanket, and a ceramic fireproof silicone rubber oversheath from inside to outside, wherein the shielding layer is woven by tin-coated copper wires. The filler is arranged on an intertwisting structure of the combined cable core. The core wire conductor is formed by tin-coated copper filaments or bunched wires formed by the tin-coated copper filaments according to a normal left-hand intertwisting mode. According to the invention, a high insulating property of the cable is ensured and a flame retardation requirement of the cable is also met; besides, a working temperature grade is substantially improved; a cable current-carrying capacity is increased; and a cable operation power is enhanced; meanwhile, the heat-resistant control cable has good performances of radiation resistance, low smoke, and halogen free performance.

The invention relates to a temperature control method based on symbol identification in a cable current-carrying capacity heat cycling test, symbol value computing is carried out on the acquired temperature and current, the symbol value which reflects the current temperature control state is obtained, the target parameters are upgraded after the symbol value judgment, a voltage regulator motor is controlled to rotate positively and negatively, the temperature rising and reducing control is realized, after the temperature reaches the set state, the symbol values of temperature and current signals are repeatedly extracted, the motor is controlled again to operate, and accordingly, the quick stable temperature control process is realized. By the temperature control method, the temperature of a cable conductor in the cable current-carrying capacity heat cycling test is quickly stabilized at the set value, the temperature control process has better robustness, the temperature overshoot and oscillation are suppressed, the whole control process is simple to realize, has less calculations and exact control logic, and can be widely applied to the conductor temperature control or the constant value control of variable parameters with the similar requirements.