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Question:

How the synchronous relays work

How the synchronous relays work

Answer:

The two alternating voltages (or currents) are applied to the primary windings of the voltage (current) transformers T1 and T2, respectively. Since the secondary winding is connected in reverse polarity, when two voltages (or currents) applied to the primary winding are in phase , The potential generated by the transformer in the secondary offset, the secondary output voltage is equal to zero. (Unbalanced voltage does not exceed 0.5V), the comparator is in the original state ("-" terminal potential below the "+" terminal potential, and output high), the implementation of the component K is not action, when the two winding on the two When the voltage difference is greater than a certain value (positive terminal voltage), the comparator flips and outputs a low level when the voltage difference is greater than a certain value (positive voltage), and the voltage difference between the transformer and the current , The execution element K is actuated.
The synchronous relay is used in the automatic reclosing line of the two-terminal power supply system as a checkout element with or without voltage and the same period. The synchronous relay consists of voltage (flow) transformers T1, T2 rectifier filter circuit, voltage comparison circuit and outlet circuit and other components, installed in the combination of plug-in shell.
When any of the input voltage (or current) is zero or very low, the situation and the two voltage (or current) are the same phase, the relay should also immediately action. The secondary output voltage is related to the phase difference and amplitude of the two inputs (or currents). When the amplitude is constant, the larger the phase difference is, the larger the secondary output voltage is, and vice versa. The setting of the relay action angle is achieved by using the potentiometer R2.

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