Reliability detecting device for miniature circuit breaker

[mini circuit breaker reliability test device]: 1 Introduction miniature circuit breaker is a kind of protective equipment, which is used to protect the safety of electrical circuits and equipment. When the electrical circuit or the electric equipment load, short circuit fault, the tripping device should be timely action, reliably cut off circuit; when the electrical circuit or the electric equipment is in normal condition, the main contact it should be reliable...

1 Introduction

The miniature circuit breaker belongs to the protection type electric appliance, which is used for protecting the safety of the electric circuit and the equipment. When the electrical circuit or the electric equipment load, short circuit fault, the tripping device should be timely action, reliably cut off circuit; when the electrical circuit or the electric equipment is in normal condition, it should be the main contact can be reliably connected to the circuit, the tripping device should not malfunction. Therefore, it is necessary to carry on the reliability test and the instantaneous reliability test to the miniature circuit breaker. In order to study the reliability of miniature circuit breakers, in addition to study the reliability index and test plan, the most important is to develop a set of reliability test equipment used to carry out the reliability standard. The only way to the research on reliability of miniature circuit breaker is implemented, and for small circuit breaker manufacturers to provide an effective means to enhance the competitiveness of products, improve product reliability.

In this paper, using a self-designed apparatus, according to the specific requirements of reliability of miniature circuit breaker testing standards and users, so that the miniature circuit breakers operation reliability and instantaneous reliability test, final test data, to identify the types of the merits of small circuit breaker.

2 hardware design of reliability test equipment

The hardware of small circuit breaker reliability test equipment is mainly composed of the test control cabinet, the test cabinet, the large current cabinet and the load circuit board.

The control cabinet is composed of a computer, printer and Advantech company's PCL-720 control card and PCL-818 card series;

The test cabinet is mainly composed of eight electric motors. Industrial control machine to control the motor driven mechanical handle, collecting the voltage at both ends of the test product contacts to determine whether the failure of the specific process as shown in figure 1.

The computer through the PCL-720 control digital output card and motor control circuit, thus, the motor switch forward or reverse driving test products. Holzer element is provided with mechanical structure of motor control, when the motor rotates in place after the Holzer component can output signals in place, through the PCL-720 control digital input card to that place and motor control through PCL-720 digital output card and the motor forward or reverse circuit is disconnected, the motor stops rotating. In the process of motor forward or backward in through the data acquisition card contacts at both ends of the voltage closed and open voltage detection voltage is not meet the requirements, if not meet the requirements of the contact failure data record.

Fig. 2 circuit model for data acquisition. When the contact is closed to be measured when the contact voltage is 0V, voltage collected by acquisition card value should be approximately 0V; when the measured contact is opened, the contact voltage is 24V, the maximum range of PCL-818HG data acquisition card for analog acquisition by 10V acquisition card before measuring, dividing and measuring by R1 and R2. So, the measured voltage value is

The high current cabinet is mainly composed of the main circuit contactor, the voltage regulator and the transformer. For C type miniature circuit breakers, the transient reliability test current is 5 and 10 times the rated current. When the 5 times the rated current, small breaker shall not operate; when the 10 times the rated current, small breaker should be timely action, reliably cut off circuit. In the process of transient reliability test, the current value can reach 5 or 10 times by adjusting the voltage regulator. Then, close the test loop to detect, through the PCL-818HG acquisition card to collect the voltage at both ends of the contact, with the collected voltage and the allowable value of the comparison, to determine whether the failure of the test.

The load circuit board is mainly to provide test conditions for the test product of 24V, 0.1A resistance load. Figure 2 shows the schematic diagram of the load circuit and the sampling circuit provided by the load circuit board. When the external power supply is 24V, the load resistance is 0.24k, which provides the load current of the circuit breaker contact with 0.1A.

3 software design of reliability test device

Software is an important part of the hardware realization of small circuit breaker operation reliability test and transient reliability test. The test device uses VC++/MFC and assembly language to write the control interface. Due to the incomplete protection of Windows 98, it is necessary to use this programming method in Windows 98 environment.

The interface of the reliability test device of miniature circuit breaker is shown in Figure 3. By clicking on the corresponding menu item, it can realize the test of miniature circuit breaker.

In this interface, click on the corresponding menu will pop up dialog box or a drop-down menu. The main functions of the application interface are test initialization, test parameter setting, test auxiliary operation, operation reliability test, transient reliability test, view data and help.

Operation flow chart application interface as shown in Figure 4, enter the application interface, the first test parameters, test initialization, if the initialization is not detected sample, the system can give reliability test tips. If the test device is tested to be tested, then click on the start of the operating reliability or the instant reliability start button.