ABB UniPack-S Steel Compact Substation

4.6 Basic Types

UniPack-S offers three basic types:

Galvanized steel foundation - requires a separate oil sump.

Concrete slab foundation - with independent oil collection pits, can be directly installed on the ground.

Compact foundation - integrated oil sump, can be directly installed on the ground.

All foundation types are designed to withstand the weight of the substation and can be lifted by a crane with four anchor points without deformation.

4.7 CSS Types

Walk in: Provides a service area independent of external conditions.

N-type (Non walk in): Optimize footprint.

Compact: Non walk-in compact version.

4.8 Installation and Advantages

The factory delivers a tested solution, and only external cables need to be connected on site. No complex civil engineering is required, just excavate the foundation pit and place the substation. The advantages include:

High security design protects equipment, personnel, and the environment;

The internal arc test complies with IEC 62271-202;

Compartment design and lockable doors;

Factory delivery reduces on-site installation time;

Ready to connect to SCADA or smart grid;

High corrosion resistance;

Lightweight and easy to transport;

Include oil collection pits to prevent transformer oil leakage and pollution;

A wide product portfolio covers various applications from power generation to secondary distribution.

Standard layout and parameters

UniPack-S offers multiple standard layouts, named Mercury, Terra, Mars, Pluto, Saturn, Luna. The main technical parameters are as follows:

Maximum transformer capacity: 3500 kVA (oil transformer)

Rated voltage: up to 36 kV

Short time withstand current of grounding network: maximum 21 kA/1s

Transformer room IP protection level: minimum IP23D, optional IP35/IP45

MV/LV compartment IP rating: IP43 minimum, optional IP54

Shell thermal rating: 10K or 20K

LV rated voltage: up to 800V

LV rated current: up to 5000A

Short term withstand capacity of LV busbar: up to 66 kA/1s

The size of each compartment is determined based on the selected equipment (such as SafeRing, SafeLink, NAL, UniSec, etc.).

Detailed explanation of core equipment

6.1 Medium voltage switchgear: SafeRing/SafePlus

SafeRing is a ring main unit used for secondary distribution networks, offering 10 configurations and suitable for 12/24kV distribution networks. Scalable and compatible with SafePlus. SafeRing is a fully sealed system, with a stainless steel air box containing all live parts and switch functions. The constant atmospheric conditions ensure high reliability and personnel safety, and are almost maintenance free.

Main modules:

C module (cable switch)

De module (direct cable connection with grounding switch)

F module (switch fuse combination)

V module (vacuum circuit breaker)

Optional modules (SafePlus): including busbar grounding, busbar segmentation, metering module, etc.

Example of rated value (12kV):

Rated current: 630A (C/F module), 200A (V module)

Power frequency withstand voltage: 28kV

Lightning impulse withstand voltage: 95kV

Short time withstand current: 16kA/1s or 21kA/3s

SafeRing comes standard with grounding switch, mechanical interlock, operating handle, padlock facilities, cable conduit, etc. Optional remote control monitoring unit, motor operation, auxiliary contacts, capacitive voltage indication system, short circuit indicator, etc.

6.2 Medium voltage switchgear: UniSec

UniSec is ABB's air insulated switchgear, which complies with the LSC2A-PM (switch isolating switch) classification according to IEC 62271-200. Constructed with pre galvanized metal sheet, each unit includes busbar room, cable room, etc. All live parts shall be air insulated and equipped with SF switches - isolating switches, withdrawable vacuum or SF6 circuit breakers. Provide multiple functional units: SDC (Switch Isolating Switch Unit), SFV (Switch Fuse+Measurement), SBC (Circuit Breaker+Switch Isolating Switch), etc. The rated voltage is 12-24kV, the main busbar current is 630/800/1250A, the maximum short-time withstand current is 25kA/3s, and the maximum internal arc withstand current is 25kA/1s.

6.3 Transformer

One or two oil immersed or dry-type transformers can be installed indoors, with a maximum single capacity of 3500kVA. Natural ventilation cooling is adopted. The dimensions of the transformer room are provided in the standard layout data sheet. Customized layouts can be provided to accommodate higher capacities. The oil collection pit can accommodate 100% transformer oil. ABB can also provide substations without transformers, and on-site installation instructions can be found in the installation manual.

6.4 Low Voltage Switchgear (LVS)

LVS is the most customized component in CSS. ABB divides it into three levels:

LVS 1: Wall mounted, suitable for small capacity and basic incoming and outgoing line needs. Bus length 5/8/12/16/20 modules (1 module=100mm). The rated current depends on the type of busbar: DIN busbar 1000-2500A, Kabeldon busbar 400-1600A, Z-type busbar 630-1900A. The incoming line can use a fuse type isolation switch (back connection) or an OETL load switch/IsoMax MCCB. The outgoing line can use fuse switches (63-630A), air circuit breakers (Emax/Emax2), and molded case circuit breakers (Tmax).