Rated voltage:
Main circuit: AC 380V / 660V (50Hz)
Auxiliary circuit: AC 220V/380V, DC 24V/48V/110V/220V
Rated insulation voltage: AC 660V / 750V / 1000V
Rated current:
Horizontal bus (main bus): 630A - 4000A (common levels: 800A, 1000A, 1250A, 1600A, 2000A, 2500A, 3150A, 4000A).
Rated current of feeder circuit: Determined by the fixed circuit breaker (MCCB, ACB) or fuse switch (such as knife fuse switch) installed in the cabinet, the common range is 16A - 2500A (ACB) / 630A (MCCB).
Rated short-time withstand current (Icw):
Horizontal bus: 15kA, 30kA, 50kA (effective value) / 1s are the mainstream levels. 65kA and above are relatively rare and require special design.
Feeder circuit: Depends on the breaking capacity and dynamic thermal stability of the circuit breaker or fuse installed inside.
Rated peak withstand current (Ipk): Usually 2.2 times of Icw (such as Icw=30kA, Ipk≈66kA).
Breaking capacity: Completely determined by the circuit breaker (ACB, MCCB) or fuse installed in the cabinet. Common:
Molded case circuit breaker (MCCB): 35kA, 50kA @400V.
Frame circuit breaker (ACB): 65kA, 85kA @400V.
Protection level:
Cabinet: IP30 is the most common basic configuration. Optional IP40, IP41, IP42, IP54 (special sealing treatment is required).
Internal compartment: There is no clear IP level requirement for independent compartments, but the component installation area is usually considered IP00.
Internal isolation form (according to IEC/GB standards):
Usually Form 1 or Form 2b.
Form 1: No internal isolation. All live parts (busbar, functional unit) are installed in the same compartment. The lowest cost and relatively lowest safety.
Form 2b: The busbar system is isolated from the functional unit (with metal partitions). There is no isolation between functional units. More secure and common than Form 1.
Simple and strong structure, low cost:
Fixed installation: All switchgear (circuit breakers, contactors, knife switches, fuses, capacitors, reactors, instruments, etc.) are directly fixed to the mounting beams or plates in the cabinet with bolts or rails. No drawers or pull-out mechanisms.
Cabinet frame: Made of high-quality cold-rolled steel plates (common thickness ≥2.0mm) or aluminum-zinc coated steel plates, welded or assembled. Strong structure and relatively simple process.
Significant cost advantage: It is one of the lowest-cost low-voltage cabinet types with the same capacity, very suitable for projects with limited budgets or uncomplicated functional requirements.
Modular partition design (basic type):
The space inside the cabinet is usually divided (physically or logically):
Busbar room: Located at the top or upper back of the cabinet, horizontal main busbars and vertical busbars (if any) are installed.
Electrical component room: The middle part of the cabinet, where circuit breakers, contactors, fuses, instruments, etc. are installed.
Cable room: The lower part of the cabinet, used for the connection and laying of incoming and outgoing cables. The space is usually large, which is convenient for wiring.
Partition: Form 2b and above will have a metal partition between the busbar room and the electrical component room.
Installation and maintenance are intuitive and convenient:
Operation and wiring in front of the cabinet/behind the cabinet: Most designs support operation of circuit breakers and observation instruments in front of the cabinet, and wiring behind the cabinet (or under the cabinet). Some designs can also be wired in front of the cabinet (such as capacitor cabinets).
Intuitive maintenance: All components can be directly accessed by opening the cabinet door, and inspection and maintenance are relatively straightforward (but power must be turned off and safety regulations must be followed).
Component replacement: It is relatively easy to replace damaged circuit breakers or fuses (need to disassemble the wiring).
High reliability and mature application:
Simple structure means fewer failure points. After long-term and extensive engineering practice verification, the operation reliability is high.
Suitable for occasions with relatively good environment and infrequent operation.
Good scalability (within the cabinet space):
The mounting beams and plates in the cabinet usually have standard hole spacing, which is convenient for adding or adjusting the installation position of components (under the premise of electrical safety distance and heat dissipation).
Flexible application:
By configuring different components, it is easy to achieve:
Incoming/receiving cabinet: Install frame circuit breaker (ACB).
Bus coupling cabinet: Install ACB to connect two sections of busbar.
Feeder cabinet/distribution cabinet: Install multiple molded case circuit breakers (MCCB) or fuse switches to supply power to multiple circuits.
Motor control cabinet: Install fixed contactor + thermal relay (but not as convenient for maintenance as drawer-type MCC).
Reactive compensation cabinet (capacitor cabinet): GGD cabinet type is widely used in capacitor compensation cabinet. Install fuses, contactors, capacitors, reactors, controllers, etc.
Lighting distribution cabinet, etc.
Optional protection level:
By adding sealing strips, special door locks, dust covers and other measures, it can meet the needs of higher protection levels (such as IP54), suitable for dusty and humid environments (such as outdoor box transformers, cement plants, etc.).
