Summary

MNS low-voltage draw out switchgear (hereinafter referred to as switchgear) is a low-voltage draw out switchgear developed by our company with reference to MNS series low-voltage switchgear and comprehensive improvement. The product is composed of standardized and series modules, and the drawer has reliable mechanical interlocking device, which makes the user safer and more reliable in use.

The switch cabinet is applicable to AC 50 (60) Hz, rated working voltage 400V and 660V The three-phase five wire power supply system with rated current of 5000A and below can be used in power plants, substations, industrial and mining enterprises, buildings, hotels, airports, docks, radio and television and other communication centers to control power generation, transmission and distribution, power conversion and power consumption equipment, and compensate the reactive power of its main bus through capacitor compensation cabinet. Conform to national standard: GB7251 Low voltage switchgear and controlgear ec60439

Model meaning

Normal service conditions

◆ the ambient air temperature shall not be higher than + 40 ℃ and not lower than - 5 ℃, and the average temperature within 24h shall not be higher than + 35 ℃.

◆ the relative humidity of the surrounding air shall not exceed 50% at a higher temperature of + 40 ℃, and there is a higher relative humidity at a lower temperature, such as 90% at + 2O ℃, but considering that moderate condensation may occur occasionally due to temperature changes.

◆ for indoor use, the altitude of the place of use shall not exceed 2000m.

◆ it shall be installed in a place without violent vibration and impact and without corrosion of electrical components.

Main technical parameters

Structure characteristics

The switch cabinet is technically improved on its original basis to make it more in line with China's national conditions. The cabinet body is made of 25mm modulus C-section through connectors to form various cabinet frame structures and drawer units that can meet various needs. High strength flame retardant engineering plastic components are used in MCC cabinet to make its safety performance more reliable. At the same time, foreign functional boards are modified and combined with 200mm modulus, It is more conducive to the design requirements of the mixed installation of PC cabinet and MCC cabinet. The extraction unit and cabinet have reliable interlocking device to prevent the on-load switching when the switch is energized and improve its safety. In addition, the cabinet is generally assembled after passivation treatment with cold-rolled steel plate, or aluminum zinc coated steel plate can be used according to the different needs of users.

◆ switch cabinet type

◇ power receiving and bus coupler cabinet

Various types of frame circuit breakers at home and abroad, such as rmw1, CW1, Na1, DW45, cdw7, MT, e and other series circuit breakers, are used as the main switch to realize the power receiving or bus coupler function.

◇ power center cabinet (PC)

Various types of cabinet frame circuit breakers at home and abroad, such as DW45, Na1, cdw7mt and E series circuit breakers, are used for power distribution. ◇ motor control center (MCC)

It is assembled by large and small drawers, and the main switch of each circuit adopts molded case circuit breaker with high breaking capacity or rotary load switch with fuse. ◇ reactive power compensation cabinet

◆ drawer type

There are five sizes, all of which are designed with modular structure based on the height of 8e (200mm). The effective component installation height is 180omm, which makes the overall layout of the cabinet more reasonable and beautiful.

8e / 4: height 200 × Width 150 × Four drawer units are combined in parallel in a depth of 400 height space

8e / 2: height 200 × Width 300 × Two drawer units are combined in parallel in a depth of 400 height space

8e: height 200 × Width 600 × A drawer unit is assembled in a deep 400 height space

16e: height 400 × Width 600 × A drawer unit is assembled in a deep 400 height space

24E: height 600 × Width 600 × Deep 400 assemble 1 drawer unit in 24E (600mm) height space

The above five drawer units can be assembled in a single cabinet or mixed assembly (see Figure 1)

◇ cabinet partition design

MNS cabinet can be composed of single-sided operation cabinet or double-sided operation cabinet as required, and each cabinet is fixedly separated into three chambers. I.e. main bus room, electrical room and cable room. (see Figure 2 for details)

◇ safety protection system

Each cabinet is equipped with a flame-retardant high-density polyurethane plastic functional board or an electroplated partition board installed between the main bus room and the electrical room, which is used to effectively prevent the accident caused by the short circuit between the flashover and the bus caused by the fault of the switching element and make the operation safer.

The upper and lower drawers are isolated by galvanized metal bottom plates with ventilation holes, which has a strong isolation effect on adjacent circuits.

A variety of plastic components are used in the cabinet to support the live parts. These components are required to be halogen-free and have anti leakage performance of cti300 grade.

The cabinet is equipped with independent PE grounding system and N neutral conductor, which run through the whole device, and the grounding or neutral connection of each circuit can be connected nearby. The installation of the whole bus system is shown in Figure 3. The frame structure is connected by self tapping screws, which has high grounding reliability. (see Figure 3 for details)

◆ bus system

The horizontal bus of the switch cabinet is arranged in the horizontal bus isolation room of the switch cabinet and can be placed behind or on the top of the cabinet. In the cabinet body of the rear outgoing line structure, the horizontal bus is placed on the top of the cabinet. The distribution bus (vertical bus) is assembled in the flame-retardant plastic functional board, which can not only prevent the discharge caused by arc, but also prevent human contact, and is connected with the main bus through the connector.

◆ electrical and mechanical interlocking of drawers

The drawer unit is equipped with reliable mechanical interlocking device, which is controlled by the operating handle and has obvious opening, closing, test, extraction and isolation positions. In order to strengthen safety precautions, padlocks can be added after the operating handle is positioned, and three more locks can be added.

◆ rear outlet switch cabinet structure

The outgoing line behind the switch cabinet can reduce the arrangement width of the switch cabinet. The main bus of the rear outgoing switch cabinet is horizontally installed on the top of the switch cabinet, the rear half of the cabinet is a cable room, and the incoming and outgoing cables are connected in the cable room behind the cabinet. The front of the switchgear is the device chamber, which is equipped with the functional unit of the switchgear. The system design moves the cable room on the side of the switchgear to the rear half of the switchgear, which greatly reduces the arrangement width of the switchgear, so as to further meet the requirements of the spatial layout of the substation.

The feeder cabinet is 600mm wide and 1000mm deep. The top is an independent bus room, which is isolated from the device chamber. The effective installation height of the front device chamber is 72e (E = 25mm), which is isolated from the rear cable chamber through the multi-function board, making full use of the installation space of the switch cabinet, with compact structure and flexible unit configuration. The rear cable room is equipped with a door, which is convenient for installation and maintenance. See Figure 4 for appearance.

The width of the incoming cabinet is determined according to the frame current of the incoming unit. The recommended width is 400, 600, 800 and 1000mm, and the cabinet depth is 1000mm.

Selection of circuit components

The components in the device mainly use the technical performance index or the imported technology, and the electrical components that can be mass produced in China.

a. DW45 series, Na1 series and AE series are mainly selected for power incoming line and feeder circuit of main circuit breaker 630A and above Column, CW or RMW series, MT series, e series or Izm series can also be selected.

b. Circuit breakers for feeder and motor control below 630A are mainly CDM1 series, CM1 series, tm30 series, NM1 series and rmm1 series, as well as NS series, s series and nzm Series Molded Case circuit breakers.

c. The AC contactor mainly adopts cdc7, LC1 series, 3TB series and CJX2 series contactors, as well as the supporting thermal relay and interlocking mechanism.

d. BH series, SDH series, LMK series, etc. are selected as current transformers.

e. The fuse shall be RT series or NB series with high breaking capacity.