Abstract : Taking the measurement of the opening and closing time of a 6.6kV R440N contactor using a TM1600 circuit breaker mechanical characteristic tester as an example, this paper introduces a method for measuring the opening and closing time of a contactor using a circuit breaker characteristic tester. This method solves the problem of measurement errors caused by the contactor coil discharging into the tester channel during testing, and expands the functionality of the circuit breaker mechanical characteristic tester. Keywords : TM1600 circuit breaker, mechanical characteristic measurement, contactor, opening and closing time. 1. Introduction The opening and closing time and phase-to-phase synchronization performance of high-voltage switchgear directly affect the normal opening and closing function and safe operation of the switch, and also relate to the safe switching of other equipment in the system and the level of internal overvoltage. Accurate measurement of these parameters is of great significance. Digital automatic circuit breaker characteristic testers are popular among users due to their convenient measurement, high accuracy, automatic waveform printing, and built-in rechargeable battery, and are widely used in the field. The opening and closing control commands designed for circuit breaker characteristic testers are generally normally open signal contacts, which control the opening and closing coils of the circuit breaker respectively. Contactors generally do not have a trip coil; they trip upon power loss, making it impossible to directly measure their opening and closing times using a circuit breaker characteristic tester. This article uses the commonly used Swedish Bulgaria TM1600 circuit breaker characteristic tester to test the opening and closing times of a French Merlin Gerin R400N 6.6kV contactor as an example to illustrate the problems encountered in the testing method and their solutions. 2. Test Principle 2.1 Principle of Measuring Circuit Breaker Opening and Closing Time The TM1600 tester has one normally open closing contact and one normally open opening contact, which control the closing and opening of the circuit breaker respectively. The measurement channel has three measurement modes: contact continuity, resistance continuity, and voltage measurement, and should be set to contact continuity connection. After issuing the command to start measuring the closing time, the normally open CLOSE contact closes, energizing the closing coil. The instrument begins recording the continuity of the primary circuit from this point as the zero time starting point. After the test, the results are printed out, showing the closing time and waveform. The measurement of the opening time is the same as above. 2.2 Principle of Measuring Contactor Closing and Opening Time The R400N contactor is closed by an energizing coil, and the method for measuring the closing time is the same as that for circuit breakers. The difference is that the closing signal from the TM1600 is a pulse with a closing time of approximately 340ms. To test the opening time, the contactor must be able to remain in the closed position; therefore, a self-holding circuit should be used to prevent the contactor from tripping after the closing pulse disappears. After the contactor is energized, the energizing coil and holding coil are connected in series to maintain its energized position with a low current. For the test, it can be considered that there is only one coil. Because the TM1600's opening signal is also a normally open contact, it cannot be used to disconnect the contactor coil; an intermediate relay must be used to convert the normally open to normally closed contact. However, when the TM1600 opening signal arrives and timing begins, the intermediate relay has not yet disconnected the contactor coil. When the intermediate relay disconnects the coil and the coil truly loses its energization, the operating time of the intermediate relay has already been introduced, making it impossible to accurately measure the opening time. To accurately determine the contactor's opening time, it's essential to know when the contactor coil loses its magnetism. Therefore, the coil's voltage signal should be input into the measurement channel, and its measurement mode should be changed to "voltage on/off." Taking the coil's demagnetization (i.e., the "off" state of the coil voltage measurement channel) as the zero-time starting point, the true opening time is obtained by subtracting the coil voltage off time from the primary circuit disconnection time. 2.3 Problems Encountered and Solutions During Testing Following the above method, the contactor's opening time significantly exceeded the manufacturer's maximum requirement (the manufacturer requires no more than 40ms, but actual measurements exceeded 100ms). Analysis revealed that the tester's voltage measurement channel has a measurement range of 12V-250V, meaning it only considers "off" when the voltage is below 12V. After the contactor coil is de-energized, its voltage begins to drop from the rated control voltage of 125V, discharging to its own protection resistor and the tester's voltage measurement channel. It takes a period of time before it falls below 12V (actual measurements show that it takes approximately 80-100ms from coil de-energization to the tester's voltage measurement channel "off"). This introduces a discharge time error into the measurement, leading to results exceeding the standard. To eliminate this error, the coil and contactor measuring channel must be immediately isolated after opening. Therefore, a normally open contact of a closing auxiliary relay is connected in series between the coil and the measuring channel. When the closing relay demagnetizes, both contacts open simultaneously, and the latter contact disconnects the coil from the measuring channel. If the two contacts of the closing auxiliary relay do not open simultaneously, it will also introduce error. Using a TM1600 to measure the synchronicity of the opening of the two contacts of the closing auxiliary relay (in this example, a Schneider LP1D12004FW contactor) showed a difference of only 0.2ms, while the contactor opening time is generally around 35ms. The pre-test procedure stipulates that the phase-to-phase closing asynchrony should not exceed 5ms, and the phase-to-phase opening asynchrony should not exceed 3ms. This error is acceptable relative to both opening time and synchronization. 2.4 Test Scheme Optimization Although the aforementioned test method can obtain correct results, the wiring is too complex and requires two auxiliary relays, which is inconvenient in use. Further optimization is possible. The test circuit wiring can be greatly simplified by replacing the closing auxiliary relay with the normally open contact of the contactor and manually opening the double air switch (in this example, the Merlin Gerin multi9 series NC100LS type switch) instead of its two pairs of normally open contacts and opening auxiliary relay. When measuring the opening time, first send a start measurement command to the tester, and then manually disconnect the double switch. The opening time is the time when the main contact is open minus the time when the voltage measurement channel is open. The double air switch has excellent fast-break opening performance. The measured opening phase difference is less than or equal to 0.1ms, and its error can be ignored. 3. Conclusion The above simple auxiliary circuit provides a simple and easy method for accurately measuring the opening and closing time of the contactor using the circuit breaker mechanical performance tester, and expands the function of the circuit breaker mechanical performance tester. References [1] DL/T596-1996, Preventive Test Procedure for Power Equipment [s] Author Introduction Wang Jiantao (1978-) Male, Engineer, engaged in high voltage maintenance. Zhang Xiaozhong (1953-) male, senior engineer, engaged in electrical maintenance. Guan Gao (1972-) male, engineer, engaged in electrical maintenance.