Intelligentized content and working principle of contactor

Update date:2018-01-22 Source:maxge

The current contactors, circuit breakers and protectors, such as thermal relay, are all mechanical non intelligent in our country. Generally, it is AC absorption, AC absorption and random separation, and the voltage of the line packet has 220V and 380V. The experiment tells us whether 220V or 380V's line package can be reliably pumped together with the DC voltage of not less than 160V, and it will not generate one or two bounce.

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At this time, as long as the suction voltage is not less than the DC 15V, the absorption state can be maintained steadily. Once the breaking process occurs, it is bound to be accompanied by an arc. The only principle to determine when the breaking process occurs is that the total energy of the arc is minimized under the premise of time allowed. For a single-phase electromagnetic circuit, the best time to break contacts should be zero crossing of main circuit current. For three-phase electromagnetic circuit, if the breaking process occurs at zero crossing time of a phase, the total energy of three-phase arc should be minimum. The zero crossing of the three contacts is controlled by rotation, which can enable them to have the same service life.

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After the power supply is connected, the rectifier circuit, the voltage regulator circuit and the single chip computer system are obtained. After the phase current setting is completed, the single chip microcomputer begins to sample and compares with the set value. The starting circuit and the continuous flow loop system are in standby state.

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At the same time of sampling, comparing and recording the voltage and phase of the power supply, the MCU waits for the start signal. If the signal is received, a corresponding high voltage will be added to the line package at the time of no more than 20ms in time, and the dynamic contact will move quickly to the static contact when overcome the spring thrust and inertia under the action of strong excitation. The single chip can judge the sucking situation of the contact and control the circuit of the continuous flow through the sensor, and provide the appropriate suction voltage in time.

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Once the power supply voltage is found to be less than the release voltage, the single chip immediately chooses the appropriate phase, stops the power supply to the line package, and the contact is reset under the action of the spring. It is obvious that the phase current increases or even exceeds the set value during the start-up process, and the degree of current surge and the duration of the surge are related to the load of the motor. This can increase the relevant procedures according to the ministerial standards and the industry requirements, and it can well distinguish different load situations or even short circuits, and automatically select the corresponding start up and protection time, so that the motor can start with load.


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