Study on calibration method of electrical parameter tester for industrial digital electronic detonator

By the end of 2022, the civil explosive industry has realized the full use of industrial electronic detonators, which has promoted the upgrading of the electrical parameter tester of industrial electronic detonators. The original calibration method can no longer meet its traceability requirements. According to the working principle of the industrial digital electronic detonator electrical parameter tester, this paper studies the calibration method of the delay time, DC resistance (firing bridge wire resistance), DC current, internal crystal oscillator signal (frequency) and other parameters, simulates and assembles a set of measuring standard device, and analyzes the sources of uncertainty of the industrial digital electronic detonator electrical parameter tester, which is solved the problem of quantity value traceability of industrial digital electronic detonator electrical parameter tester in civil explosive industry.


Introduction
Industrial digital electronic detonator is an electric detonator that uses an electronic control module to control the initiation process.Its electronic control module is inside the detonator and has the control of detonator initiation delay time and initiation energy [1].Especially, the detonator initiation password and information identity password are built in the chip to ensure that the digital electronic detonator can strictly control the initiation delay time, compared with traditional electric detonators and detonators, its accuracy has obvious advantages [2].Industrial digital electronic detonator is a new product encouraged by the development of the civil explosive industry.The measuring instruments in the traditional civil explosive industry are facing upgrading.
At present, there is no comprehensive industrial digital electronic detonator electrical parameter tester in the domestic market.Although some civil explosive enterprises have developed a specific model of digital electric detonator electrical parameter tester, it is only for testing the electronic digital detonator products produced by themselves [3].The civil explosive industry has realized the full use of industrial electronic detonators, which not only accelerates the upgrading of the original industrial electric detonators in the civil explosive industry, but also promotes the upgrading of the measuring and testing equipment.The measuring instruments in the traditional civil explosive industry, such as electric detonator tester, electric detonator resistance tester, millisecond detonator tester, second detonator tester, industrial explosive detonation velocity tester.The intelligent detonation velocity tester is facing the situation of obsolescence, and the new industrial digital detonator electrical parameter tester came out [4].
According to the specification WJ9047-2004 "the calibration specification of industrial electric detonator electrical parameter tester" cannot meet the calibration requirements of industrial digital electronic detonator electrical parameter tester.The purpose of the research on the calibration method of the industrial digital electronic detonator electrical parameter tester is to solve the problem of quantity value traceability of the digital electronic detonator electrical parameter tester in the civil explosive industry, and to study the calibration method of the industrial digital electronic detonator electrical parameter tester.This method can not only solve the calibration of the industrial digital electronic detonator electrical parameter tester in the civil explosive industry, but also solve the problem of quantity value traceability of the measuring and testing equipment for initiating explosive devices [5].

Research contents
The research on the calibration method of the industrial digital electronic detonator electrical parameter tester mainly focuses on the parameters such as delay time, DC resistance (ignition bridge wire resistance), DC current, internal crystal oscillator signal, etc.The research content of this calibration method is mainly from the following five aspects.

Delay time test system
The calibration of the delay time test system can directly calibrate the delay time of the industrial digital electronic detonator electrical parameter tester, which is reserved for the measured test interface.

DC resistance test system
The calibration of the DC resistance test system can directly calibrate the DC resistance parameters of the industrial digital electronic detonator electrical parameter tester, which is reserved for the measured test interface.

DC current test system
The calibration of the DC current test system can directly calibrate the DC current parameters of the industrial digital electronic detonator electrical parameter tester, such as working current, communication current, detonating capacitance current, charging current, which is reserved for the measured test interface.

Internal crystal oscillator signal
The calibration of the internal crystal oscillator signal can directly calibrate the internal crystal oscillator signal of the industrial digital electronic detonator electrical parameter tester, which is reserved for the measured test interface.

Detonator analog device
The calibration of industrial digital electronic detonator analog device is to calibrate DC current, DC resistance, delay time and internal crystal oscillator signal of the industrial digital electronic detonator electrical parameter tester through the analog device, without reserved measurement and test interface.
The research on the calibration method of industrial digital electronic detonator electrical parameter tester is divided into two categories according to whether the measurement and test interface is reserved, one is the tester with the measurement and test interface reserved, and the other is the tester without the measurement and test interface reserved.

Calibration of delay time
As shown in Figure 1, setting industrial digital electronic detonator electrical parameter tester to the measurement function block, standard time is generated to calibrate electrical parameter tester by time interval generator [6], then it is calculated the delay error through calibration specification WJ9085-2015"Industrial Digital Electronic Detonator".The delay time error involves state time delay, control input time delay as well as parameter uncertainties, the expanded uncertainty is less than one-tenth to introduce allowable error by standards, auxiliary equipment and environmental conditions.

Calibration of DC resistance
As shown in Figure 2, set the industrial digital electronic detonator electrical parameter tester to the resistance test function, adjust the adjustable DC resistance (ignition bridge wire resistance), and calculate the measurement error of DC resistance [7].According to the investigation and data review, the measurement range of ignition bridge wire resistance is generally from 2 Ω to 3 Ω, and the accuracy of ignition bridge wire resistance is not high.The DC resistance box is selected as the measurement standard, and the maximum allowable error of the DC resistance box, such as ×0.1 Ω disk: ± 0.5%, ×1 Ω disk: ± 0.05%.

Calibration of DC current
As shown in Figure 3, set the industrial digital electronic detonator electrical parameter tester to the corresponding current test function, adjust the adjustable resistance, make the total load resistance value near the middle value of the resistance measurement range, and measure the loop DC current.General industrial digital electronic detonator electrical parameter tester BUS input terminal voltage is 8.5 V, working current measurement from 10 μ A to 2 mA.The maximum allowable error of the measuring standard instrument shall not be greater than 1/3 of the calibrated tester.As shown in Figure 4, the frequency fluctuation and frequency accuracy of the internal time base of the industrial digital electronic detonator electrical parameter tester can be measured directly using a universal counter.The maximum allowable error of the measuring standard instrument shall not be greater than 0.1 of the calibrated tester.

Calibration method for no reserved metering test interface
For the tester without reserved measurement and test interface, it is necessary to analyze the working principle of the digital electronic detonator to design the industrial digital electronic detonator simulation device.Digital electronic detonator is an electric detonator that uses an electronic control module to control the detonating process.Its electronic control module is inside the detonator and has the control of detonating delay time and detonating Especially, the detonator initiation password and information ID password are built in the chip to ensure that the digital electronic detonator can strictly control the detonating delay time, compared with traditional electric detonators and detonators, its accuracy has obvious advantages [8].As shown in Figure 5, the basic structure of the digital electronic detonator is shown in Figure 5.It is mainly composed of ignition head 1 (or ignition bridge wire resistance), lead tube 2, delay charge 3, ignition hole 4, primary explosive 5, reinforcing cap 6, secondary charge 7, main charge 8, detonator shell 9, plastic head 10 and pin wire 11.The industrial digital electronic detonator simulation device is designed according to the internal structure of the digital electronic detonator.The simulation device is not included primary explosive 5, secondary charge 7, and main charge 8.The simulation device is designed according to the working principle of the digital electronic detonator.Firstly, the design principle of delay time, DC resistance or firing bridge wire resistance, and DC current in the working circuit of the internal chip of the electronic detonator is studied, and the calibration method of calibrating the industrial digital electronic detonator tester is analyzed by using the industrial digital electronic detonator simulation device [9].Secondly, it is necessary to study the calibration method of crystal oscillator signal in the industrial digital electronic detonator tester.

Simulated firing bridge wire resistance
The firing bridge wire resistance with high accuracy is selected, the bridge wire resistance is relatively small affected by temperature.After long-term stability assessment and confirmation, it can be used as a measurement standard which can directly calibrate the DC resistance function of the industrial digital electronic detonator electrical parameter tester or the industrial digital electronic detonator resistance tester.

Calibration of DC current
DC ammeter is connected in series in the simulated firing bridge wire resistance circuit to measure the initiating capacitance current.The DC stabilized power supply is used to output from 8 V to 20 V DC voltage, which is applied to both ends of the input protection control circuit BUS.The working current and communication current can be measured by series DC ammeter, in the charge and discharge control circuit, the DC series ammeter can measure the charging current.

Calibration of delay time
As shown in Figure 6, the calibration delay device is connected with precision instrument by programmable storage control module.Firstly, test circuit need to connect a precision time measuring device in order to setting a delay time as a trigger starting signal.Secondly, it is verifying a ID password so that confirming identity information, when delay time is up, the capacitor is discharged instantly as well as test current loop is exploded.Finally, measuring indication are compared with standard and measured instruments, then it needs to calculate the error [10].

Calibration of time-based crystal oscillator signal
Without reserved measurement and test interface, the calibration of the time-base crystal oscillator signal of the industrial digital electronic detonator tester ,which can be calculated by referring to the calculation method of the time reference accuracy of the digital electric stopwatch in the JJG237-2010 "stopwatch verification regulation", through the delay time setting value T and the delay time measurement value T 0 , and through an Equation ( 1).
(1) 1 V~30 V ±1×10 -5   Universal counter SS720A 100 Hz~200 MHz ±1×10 -8   Time interval generator WBY-I 1 μs ~ 10 s ±5×10 -7   In this paper, an industrial digital electronic detonator tester is calibrated by this calibration method, models for EVTT-MA-B101A00, the calibration parameters such as time interval, DC voltage, DC current and DC resistance.The selection of measurement standards is shown in Table 1.In order to verify the feasibility of the calibration method by means of measurement audit as shown in Formula (2), a result of quantity audit is judged according to CNAS-GL002 "The guide of statistical processing and capability evaluation of capability verification results".

Test data analysis
(2) x lab -Taken the measurement to give in the laboratory, x ref -Leading laboratory measurements.As shown in Table 2, the results of the survey audit are satisfactory.It meets the requirements of CNAS capability verification field and frequency, and proves that the laboratory's technical capability conforms to the quality and validity of CNAS accreditation.After evaluation and analysis, the uncertainty of the digital electronic detonator electric parameter tester is as follows.After evaluation and analysis, the uncertainty of the calibrated industrial digital electronic detonator electrical parameter tester is as follows, take the confidence probability 95%.DC resistance is from 1 Ω to 100 Ω, its uncertainty is equal to 0.1%.DC current is from 10 μA to 20 mA, its uncertainty is equal to 0.1%.DC Voltage is from 1 V to 30 V, its uncertainty is equal to 0.01%.Delay Time is from 1 ms to 100 ms, its uncertainty is equal to 0.02 ms.Frequency is from 10 kHz to 200 MHz, its relative uncertainty is equal to 2×10 -7 .

Conclusions
According to the technical requirements of industrial digital detonator products in the industrial standard WJ9085-2015 "Industrial Digital Electronic Detonator", combined with the metrological performance requirements of the traditional electric detonator electrical parameter tester [11], after the preliminary investigation of the production situation of many civil explosive enterprises.
As well as the research of EVTT19A-01B delay precision tester (industrial digital electric detonator electric parameter tester) and EDF-IA electronic digital detonator control module developed by Rongsi Sichuang (Beijing) Technology Co., Ltd., a set of industrial digital electric detonator electric parameter tester calibration device is designed using the calibration method studied in this paper.After practical analysis, it can not only solve the problem of quantity value traceability of industrial digital electronic detonator electric parameter tester in civil explosive industry, but also solve the problem of quantity value traceability of measuring and testing equipment in initiating explosive device manufacturers.

Figure 4 .
Figure 4. Calibration of internal time base signal.

Figure 5 .
Figure 5. Profile of digital electronic detonator.

Figure 6 .
Figure 6.Working principle diagram of industrial digital.

Table 1 .
Standard of measurement.

Table 2 .
The extended uncertainty associated with the corresponding measurement results as assessed by the laboratory, -Reference laboratory-assessed extended.If | E n | ≤1 is a satisfactory result, or |E n | 1 is an unsatisfactory result.Measurement audit data. 6-