SECONDARY SKID UNIT (SSU)

Prefabricated semi open design secondary solution

SECONDARY SKID UNIT (SSU)

<p>Secondary Skid Unit (SSU), available for ratings up to 40.5 kV and 25 kA, is indoor or outdoor open frame mounted, compact solution with factory installed equipment and interconnections enabling an efficient construction schedule by supplying a pre-engineered, pre-installed and pre-tested system.<br> </p> <p>Secondary Skid Unit offers a prefabricated semi open design that reduces installation and deployment costs in secondary distribution installations. It supports transformers up to 7,500 kVA.</p> <p>Secondary Skid Unit is ideal for a site with limited access for the general public, mainly for industrial or renewable energy sites, being a step-up unit in a solar site with a 175-185 kW string inverter topology, datacenter and industrial application.</p>

Product scope

  Secondary Skid Unit (SSU)
Max. rated voltage 40.5 kV
Max. transformer rating 7500 kVA
Max. rated short-time withstand current MV 25 kA 1s
Internal arc classification IAC-A 20 kA 1s per IEC62271-212
Medium voltage switchgear type - SF6-insulated
- SF6-free (dry air)- no IAC classification
Low voltage switchboard -  UniPack low voltage distribution board (LVS)
-  Incomer – Molded Case Circuit-Breakers (MCCB) or Air Circuit Breaker (ACB)
-  Distribution – fuse switch disconnector or MCCB
Rated voltage low voltage up to 800 VAC
Standards IEC62271-212
IP class MV LV/TR (up to) IP54/XX
Applications Ideal for a site with limited access for the general public, mainly for industrial or renewable energy sites, being a step-up unit in a solar site with a 175-185kW string inverter topology, datacenter and industrial application.

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FREQUENTLY ASKED QUESTIONS

Secondary Skid Unit (SSU) is part of ABB’s integrated secondary solutions. It offers is a type tested, and arc tested assembly solution comprising an enclosure containing medium voltage (MV) switchgear, distribution transformers, low voltage (LV) switchboards, connections and auxiliary equipment to supply low voltage energy from medium voltage systems and vice versa. Secondary Skid Solutions (SSU) offers a prefabricated semi open design for secondary solutions. It is ideal for a site with limited access for the general public. It fits transformers up to 7,500 kVA.

Secondary Skid Solutions (SSU) offers a prefabricated semi open design for secondary solutions. It is ideal for a site with limited access for the general public. It fits transformers up to 7,500 kVA. Selected variants of Secondary Skid Unit (SSU) are designed and tested to IEC 62271-212 with IAC-A 20kA 1s for maximum operator and public safety. ABB offers small single structure to large multiple structure solutions. SSU may include an oilpit. ABB components ensure long service life, high reliability, and resilience to grid disturbances.

All three solutions offer an enclosure containing medium voltage (MV) switchgear, distribution transformers, low voltage (LV) switchboards, connections and auxiliary equipment to supply low voltage energy from medium voltage systems and vice versa. Key differences are:

  • UniPack is compact secondary solution type tested per IEC62271-202 for safety of personnel and general public. It offers electrical segregation between compartments and oil containment features. UniPack’s enclosure can be steel or GRP material for harsh environments and it is suitable for urban sites. UniPack fits transformers up to 3,500 kVA. 
  • EcoFlex offers standard ISO transportation dimension & certification for secondary solutions. EcoFlex is optimized for simple economical transport (sea, rail, road), robust and relocatable. It may include an oilpit. It is optimal with 330-350 kW string inverter setup and fits transformers up to 6,300 kVA. 
  • Secondary Skid Solutions (SSU) offers a prefabricated semi open design for secondary solutions. It is ideal for a site with limited access for the general public. It fits transformers up to 7,500 kVA.