MNS Low voltage withdrawable switch Cabinet

MNS Low pressure draw-out switchgear

     This series of low-voltage pull-out switchgear is a modular factory-assembled (FBA) cabinet whose technology has reached the international level in the late 1990s. This series of low-voltage extraction switchgear is suitable for power conversion, distribution and control of power distribution equipment of power system with rated working voltage of AC 50~60Hz and below AC 660V in power plants, substations, petrochemical industry, metallurgy, steel rolling, transportation, energy, light industry, textile and other factories and mining enterprises, residential areas, high-rise buildings and other places.

     The device conforms to GB7251.1 "Low-voltage Switchgear assembly" and JB/T9961 "Low-voltage extraction switchgear assembly" national professional standards, and in line with IEC439-1, VDE0660 part V and other international professional standards.

Normal operating environment conditions

1. The ambient air temperature shall not be higher than+40C, not lower than -5C, and its average temperature shall not be higher than+35C within 24 hours

2. Atmospheric conditions: The air is clean, and the relative humidity does not exceed 50% at the highest temperature of+40C. Higher relative humidity is allowed at lower temperatures, such as 90% at+20C. However, temperature changes should be taken into account, which may cause occasional condensation.

3. The altitude shall not exceed 2000m.

4. This device is suitable for transportation and storage processes at temperatures ranging from -25 ° C to+55 ° C, up to+7 in a short period of time (not exceeding 24 hours). Under these extreme temperatures, the device should not suffer any irreparable damage and should be able to operate normally under normal conditions.

5. If the above usage conditions cannot be met, it should be resolved through negotiation between the user and the manufacturer. 6. When this device is used on offshore oil drilling and production platforms and nuclear power plants, a separate technical agreement should be signed.

Basic technical parameters

1. Electrical performance

2. Protection level

Complies with IEC529 and DIN40050 standards

IP30 for solid protection greater than 2.5mm

IP40 for solid protection greater than 1.0mm in diameter

IP54 provides protection against dust and splashes from any direction

Cabinet structure

The basic structure of the switchgear cabinet body is composed of C-shaped profiles, which are bent from steel plates with E=25mm as the module installation hole. All cabinets and inner partitions are galvanized and purified. The surrounding door panels and side panels are subjected to high-voltage electrostatic spraying. The basic structure of the cabinet is shown in Figure 1: the basic dimensions of the cabinet are shown in Figure 2. Tables 1 and 2

Switch cabinet type

1. Power distribution center cabinet (PC): Emax, MT3WNAH, ME series and other circuit breakers can be used.

2. Motor control center cabinet (MCC: assembled from large and small pull-out assemblies, with high breaking molded case circuit breakers or rotating load switches with fuses for each circuit main switch. Power factor automatic compensation cabinet (with manual, automatic, and remote power factor compensation devices)

A Power Distribution center (PC) cabinet      

B Motor Control center (MCC) cabinet

Partition design of cabinet body

1. Medium (PC)

(1) The PC cabinet is divided into three compartments;

Horizontal busbar compartment: at the rear of the cabinet;

Functional unit compartment: located on the upper or left side of the cabinet front;

(2)The horizontal busbar compartment is separated from the functional unit compartment by steel plates. The control circuit compartment and the functional unit compartment are separated by a flame-retardant polyphenylene ether plastic shell.

(3) The frame type circuit breakers installed inside the cabinet can be manually operated outside the cabinet when the door is closed. Observe the opening and closing status of the circuit breaker and determine whether the circuit breaker is in the test position or in the working position based on the position relationship between the operating mechanism and the door.

(4) A component partition structure is designed between the main circuit and the auxiliary circuit, and the auxiliary electrical unit composed of instrument signal lights and buttons is installed on the material board, with flame retardant polyurethane foam used behind the board.

The cover made of plastic is separated from the main circuit.

2.Withdrawable motor control centers and small current power distribution centers (MCC)

 The withdrawable MCC cabinet is divided into three compartments, namely the horizontal busbar compartment behind the cabinet, the functional unit compartment on the left front of the cabinet, and the cable compartment on the right front of the cabinet. The horizontal busbar compartment and functional unit compartment are separated by functional boards made of flame-retardant foam plastic, and the cable compartment is separated from the horizontal busbar compartment and functional unit compartment by steel plates. The drawers of MCC (Motor Control Center) are divided into the following 5 types:

8E/4: Height 200x Width 150x Depth 400mm

8E/2: Height 200X Width 300X Depth 400mm

8E: Height 200x Width 600x Depth 400mm

16E: Height 400mm x Width 600mm x Depth 400mm

24E: Height 600mm x Width 600mm x Depth 400mm

3. Rear outgoing switch cabinet structure

he rear outgoing line is designed to reduce the width of the switchgear arrangement. The main busbar of the switchgear is horizontally installed at the top of the switchgear, and the rear half of the cabinet is a cable compartment. The incoming and outgoing cables are all connected in the cable compartment behind the cabinet. The front of the switchgear is a device compartment, which houses the functional units of the switchgear. The system design moves the cables on the side of the switchgear to the rear closing cabinet, greatly reducing the arrangement width of the switchgear to further meet the requirements of the spatial layout of the substation

The bond power cabinet has a width of 600mm and a depth of 1000/1200mm. The top is an independent main busbar compartment, which is isolated from the device compartment. The effective installation height of the front device compartment is 72E (E=25mm), which is isolated from the rear cable compartment through a multi-functional board, fully utilizing the installation space of the switchgear. The structure is compact and the unit configuration is flexible. The back compartment is equipped with a door for easy installation and maintenance. The width of the incoming cabinet is determined by the frame current of the incoming unit, with a recommended width of 400/600/800/1000mm and a cabinet depth of 1000mm

Bus system

The switchgear can be equipped with two sets of main busbars, installed in the rear busbar compartment of the switchgear. Two sets of busbars can be installed separately in the upper and lower parts of the cabinet. According to the needs of the incoming line, the upper and lower sets of busbars can be made of different or the same cross-section materials. Both can be powered separately, in parallel, or as backup power sources.

The distribution bus (vertical bus) is assembled in the flame-retardant plastic function board and connected with the main bus through special connectors, which can not only prevent the discharge caused by arc, but also prevent human contact. The cabinet is equipped with independent PE earthing system and N neutral conductor. Both run through the entire device and are installed at the bottom and right side of the cabinet. Each circuit can be connected to the nearest ground or neutral connection. The entire busbar system installation is shown in Figure 3. All cabinet frame structural components are connected with self tapping screws, which has high grounding reliability.

The neutral busbar and neutral protection busbar are installed parallel to the lower part of the functional unit compartment and vertically in the cable compartment. If an insulator is used to separate the N line from the PE line, the N line and the PE line should be used separately. If a conductor is used to short circuit the two lines, they become PE/N lines.

Protective earthing system

       The protection circuit of the device consists of two parts: a PE wire (or PE/N wire) installed separately and running through the entire length of the arrangement, and a conductive structural component. The metal structural components in the device, except for the exterior doors and sealing plates, are all galvanized. At the connections of the structural components, they are carefully designed to withstand a certain short-circuit current.

Auxiliary circuits and cable trays

       The top of the functional unit compartment is equipped with an auxiliary circuit cable tray, which can accommodate cabinet to cabinet connections and public power lines.

Cable and control line connection

       On one side of the withdrawable component, the cable compartment is equipped with wiring devices and terminals for connecting the outgoing power and control wires to the component. The incoming and outgoing cables and control wire wiring devices are arranged on the track on the right side of the cable compartment. The main circuit terminal is located at the rear, and the control line terminal is located in the front 45 ° direction. The wiring of control wire terminals can be connected with screws or plug-in wire noses or with copper connectors. If the main circuit terminal on the adapter of the withdrawable component is less than 63A, it is equipped with a PE terminal.

Security protection system

        Each cabinet is equipped with one or a group of flame-retardant plastic functional boards, installed between the main busbar room and the electrical room. Its function is to effectively prevent accidents caused by flashover and short circuit between the busbar caused by switch components due to faults, and strict isolation measures are taken.

There is a galvanized metal base plate with ventilation holes between the upper and lower drawbars for isolation. The smaller 8E/4 and 8/2 drawbars are surrounded by flame-retardant engineering materials, so there is a strong insulation and isolation effect between adjacent circuits. Various plastic components are used inside the cabinet to support the live parts, which are halogen-free and have anti leakage performance above CT1300 level.