The main component of an AC voltage transformer, which can convert a voltage AC power to another voltage of the same frequency, is a core and two windings placed on the core. The coil connected to the power supply receives alternating current energy, which is called the primary winding and the coil connected to the load, and sends the alternating current energy. The voltage phasor U1 of the secondary winding called primary winding of the secondary winding is the voltage phasor U2 current phasor I1 current phase. The amount of I2 electromotive force phasor E1 electromotive force phasor E2 turns N1 turns N2 at the same time and the phasor of the secondary winding flux is φm. This magnetic flux is called the main flux.
In the study of the operation and failure of the power system and the countermeasures to deal with abnormal reactions, in these processes, relays with contacts are mainly used to protect power systems and components such as step-down transformers, generators, and transmission lines to avoid them. Damage, this is also called relay protection, it is mainly in the power system failure can be sent to the operating staff in a timely manner to send an early warning signal, or to the control of the circuit breaker issuing ICJ jump command to control the fault from the failure The recent jump of components of the ICJ device allows the faulty component to be disconnected from the power system in a timely manner, thereby reducing the damage of the power component to a greater extent and reducing the risk of power supply security. Therefore, it is important to understand the principle of the relay protection device. The right figure is a type of relay protection mechanism diagram .
When there is an abnormality in the step-down transformer in the power system, in addition to strengthening supervision, it is also necessary to contact the relay protection personnel to handle the protection that may cause misperception and retreat the exit pressure plate. The following exceptions are common when exiting. Happening
(1) In the event of signals such as "master differential AC short-term" and "master differential DC voltage disappearance", there are busbar unbalanced currents and non-zero bypass busbars. We must pay more attention to it.
(2) When the DC current disappears and there are periodic channel test parameters that do not meet the requirements, when the device fault or channel abnormal signal is sent back and cannot be returned, the insurer will need to make a timely exit response; also in the transformer operation When refueling, filtering oil or changing silica gel; need to open the respiratory system to discharge oil plugs, bleeders and the like, all require strict monitoring, one party's relay protection problems, of course, there will be some corresponding protective measures against these problems.