A low-voltage motor control system

Abstract

The invention discloses a low-voltage motor control system, which comprises an electric loop and a ZKK control loop. The electric loop is formed by a moulded case circuit breaker, a plugin and a motor load which are sequentially connected by a phase line A, a phase line B and a phase line C of a three-phase alternating-current power supply. The ZKK control loop comprises a ZKK electric operating mechanism and at least one group of closing circuit and opening circuit, wherein the ZKK electric operating mechanism is powered by a direct-current power supply, the at least one group of closing circuit and opening circuit is connected with the ZKK electric operating mechanism, and the ZKK electric operating mechanism is used for controlling the closing and opening of the moulded case circuit breaker. Compared with an original contactor scheme, the scheme that the moulded case circuit breaker is configured with the electric operating mechanism has the advantage that the required space is much more less; according to the scheme that the moulded case circuit breaker is configured with the electric operating mechanism, the original control requirements can be met, secondary configuration is simplified, space in a drawer is larger, normal heat radiation of equipment during operation is facilitated, and the long-term safe operation of the equipment is favored.

Description

technical field [0001] The invention relates to the field of low-voltage power distribution, in particular to a low-voltage motor control system. Background technique [0002] Most of the 380V low-voltage motors in power plant projects are controlled by contactors. Generally, closing and tripping relays are used to separate the closing circuit and tripping circuit. For the power circuit, see figure 1 , see the attached electrical control circuit diagram for details figure 2 ; The working principle of its control loop: [0003] a. Start: the control circuit miniature circuit breaker DK is energized. If the transfer switch ZK is switched to the local position, the connection between ZK: 3 and ZK: 4 will be connected. Because the control circuit of the tripping relay TJ is in the disconnected state, it will be closed at this time. The TJ closed point in the gate circuit remains unchanged. If the closing button HA is pressed, the closing relay coil is energized, and the HJ op...

AI Technical Summary

Problems solved by technology

[0005] As mentioned above, the control circuit of this type of scheme contains more components, the secondary circuit is more complicated, and the motor circuit is generally installed as a drawer

Due to the relatively fixed positions of the molded case circuit breakers in the drawers of various drawer cabinets (including MNSG cabinets, GCS, GCK and new general-purpose cabinets), the primary input and output terminals are relatively fixed, so the remaining space in the drawer is very limited. There are too many configurations of sub-components, and a slight improper selection of closing and opening relays will cause the components in the drawer to be installed, or all components are barely installed in the drawer, but it is difficult to dissipate heat during normal operation of the equipment, which will affect the life of the components. It is a very big test for safety and use, and it also lays a lot of hidden dangers for future failures.

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