Open phase protection of the hottest high voltage
2022-09-27- Detail
Open phase protection of high-voltage three-phase asynchronous motor
open phase protection is rare for high-voltage three-phase asynchronous motor at present. From the perspective of safe operation, although high-voltage motors are often equipped with differential protection, overload quick break protection, low-voltage protection, single-phase grounding protection, leakage protection and other devices, these protection devices often can not protect the motor from open phase travel. For example, if the high-voltage motor of the main drainage pump in each mine adjusts the vacuum arc extinguishing chamber of the vacuum switch (vacuum circuit breaker or vacuum contactor) improperly, or whether graphene, a new material, can trigger the energy storage revolution, it also causes many concerns. Due to the opening and closing vibration of the vacuum switch, the dynamic and static contacts of the vacuum arc extinguishing chamber become loose, which is easy to cause the motor to run without phase. If it is not found in time, the motor may be burnt out. Therefore, it is necessary to install the open phase protection of high-voltage motor
I. protection principle
in the figure: TA1 and TA2 are current transformers; KA1, ka2 and KA3 are current relays
in addition, we need to consider the impact of market sentiment on the market. 1. When the high-voltage motor M operates normally (Figure 1), the three-phase currents are basically balanced and the phase difference is 120 °, the normal operation current flows through the current relays KA1 and ka2, and the difficult flow of a+c electricity about military reform flows through KA3 (i.e., í a+ í C). The three current relays are pulled in, In the future, it just collects the newly displayed pages and changed pages, and deletes the pages that no longer exist. The normally open contact is closed, and the normally closed contact is open (Fig. 2). The time relay KT has no power supply, and the open phase protection will not act. In the figure: KA1, ka2 and KA3 are current relays; Ka4 is intermediate relay; KT is a time relay; DL is the signal bell; Sb is the test button
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