When electrical requirements exceed available switchgear space

Modern MV installations increasingly encounter situations where electrical requirements exceed the physical limitations of switchgear cable compartments. As transformer ratings increase, multiple parallel cables per phase may be required to satisfy current-carrying capacity and short-circuit requirements.

However, switchgear cable compartments do not always provide sufficient space for all required cable terminations. Physical space limitations, termination constraints and cable bending radius requirements can make direct connection difficult.

The challenge

A common example is the connection of large power transformers to MV switchgear. While the electrical design may require multiple parallel cables per phase, the switchgear incomer cubicle may only provide limited space for cable terminations or may not permit multiple cable lugs to be mounted correctly on the same terminal pad.

For example, an installation may require two parallel cables for each phase. Instead of a single L1, L2 and L3 conductor, six cables need to be terminated inside the switchgear. While the electrical design provides the required capacity, available switchgear space and cable bending radius requirements may prevent all cables from being connected as intended.

Where this challenge occurs

Space constraints in MV switchgear can occur across a wide range of medium-voltage infrastructure projects where increasing power requirements must be integrated into existing installations.

Battery Energy Storage System (BESS) connection and retrofit

Battery energy storage systems are increasingly connected to existing medium-voltage grids to support grid stability and energy balancing. In both new BESS connection projects and BESS retrofit projects, higher cable capacities may be required while existing switchgear remains in service. In these situations, available termination space can become a limiting factor.

Grid expansion and transformer upgrades

Grid expansion projects and transformer upgrades may require multiple parallel cables per phase to satisfy increasing power demands. In these situations, switchgear cable compartments may not provide sufficient space for all required terminations.

Renewable energy transformer stations

Large renewable energy transformer stations increasingly require higher cable capacities and more complex cable layouts. Physical limitations within switchgear can therefore become an important engineering consideration during project design and implementation.

More about Joints for Renewables

Conventional approaches and their limitations

When switchgear cannot accommodate the required number of cable terminations, several options may be considered.

Replace the switchgear

Replacing the switchgear provides a permanent solution but may involve high costs, long lead times, redesign work and extended project schedules.

Modify the cable compartments

Existing switchgear can sometimes be modified to create additional space. However, modifications may require approval, significant site work and additional engineering effort.

Operate with fewer parallel cables

Reducing the number of parallel cables can simplify installation, but may reduce current-carrying capacity and potentially conflict with the original electrical design requirements

An alternative approach

A branch joint can be used as a cable consolidation point outside the switchgear. Instead of bringing all parallel cables directly into the cable compartment, two parallel conductors can be combined into a single outgoing conductor before entering the switchgear. This reduces the number of required terminations while maintaining the intended current-carrying capacity.

By consolidating conductors before they enter the switchgear, cable compartment congestion can be reduced without modifying the existing switchgear. At the same time, cable bending radius requirements can be maintained and the original electrical design can remain unchanged.

Key benefits: