11kV Switchgear

Now that we have learned about medium voltage switchgears, let gets into the more specific voltages; what exactly is 11kV switchgears?

What is 11kV Swithgear?

An 11Kv switchgear is a type of medium voltage switchgear and can either be gas insulated or air insulated. It is applied to medium voltage electrical distribution networks such as mall buildings, residential area and airports.

Arrangement

The 11kV switchgear arrangement is made up of several interconnected, functional units. An indoor switchgear usually comprises of the following:

Connection of 11 kV feeders
Bus tie cables
System transformer and distribution transformer circuits to the 11 kV busbar
Isolation and earthing of feeders
VTs, CTs and auxiliary wiring
IEDs for SCS
Port to SCADA of region DCC
Alarm lamps

And other instruments that must be constructed according to IEC 62271-1 and 62271-200.

Assembly

The switchgear is assembled as individually-grounded, compartmentalized steel structures. Each compartment has doors, barriers, and removable access panels to isolate the separate working functions. At the front panel of each switchgear, a diagram showing the main components and their connections must be featured.

The metal cubicles must be protected from dust, water exposure as well as insects. This is to ensure proper function of the switchgear and complete protection of the cabling inside.

What is the difference between 11kV and 33kV voltages?

Both 11kV and 33kV switchgears are medium voltages. However, the voltage differences mean their location and usages are slightly different. Learn about the differences here;

11kV lines are more common in residential areas and feeds local transformers, which is then distributed to consumers’ homes and offices.
33kV on the other hand, involves much higher voltages and is not usually found that close to residential areas. They are used to distribute power from one small sub-station to another.
11kV have higher current component as opposed to 33kV, hence it is usually for shorter distance transmission.

From 33kV to 11kV – What is the Process?

Going from higher to lower voltages require a step down to get to the safe level. The reason why the voltage starts from higher to lower is due to the fact that some transmission gets lost during the process. In the case of longer distances, a much higher voltage is required for the power to be transferred. Then, at the substation, the voltage can be stepped down.

Trivia: Why is the voltage calculated as 11KV and 33KV, and not in 10KV or 30KV?

This interesting designation comes from the fact that the voltage needs to be transmitted over long distance. Consider this situation:

The power generation companies used to generate round figure voltages like 10kV, 20kV, and 60kV, for instance. But during transmission, there is a considerable amount of voltage drop due to the long distance to transmit the power. This drop is being calculated nearly 10% based on Physical factors. That is one of the main reasons why power generation companies add 10% more in their actual target. This will then neutralize the line losses, so the receiving end will get the targeted result.

Example:

Net Voltage = Target Voltage + 10% of Target Voltage

→ 33kV = 30kV + 3kV

→ 11kV = 10kV + 1kV

At EPE Switchgear, we provide safe and reliable switchgears for both 11kV and 33kV uses. To learn more about these two products, head over to our product specifications and their respective details.