NOJA Power OSM Reclosers used in capacitor switching applications

Electrical switchgear manufacturer NOJA Power today announces that its OSM Automatic Circuit Reclosers (ACRs or “reclosers”) are being successfully utilised as capacitor switches in Colombia.

NOJA Power reclosers can be utilised in situations beyond the traditional protection grading and rapid restoration of power supply after a fault. One such application is the protection and control of capacitor banks in the distribution network.

Capacitor banks are installed in power networks to minimise losses resulting from reactive power, subsequently lowering operating costs. As capacitor banks alone cannot be controlled to meet the requirements of the power network, a basic capacitor bank installation can be improved by adding a switch between the capacitor bank and substation. This allows the power utility to connect or disconnect the capacitor bank from the network.

Basic capacitor bank installations can be upgraded into switched capacitor banks by including a NOJA Power recloser between the capacitor bank and the substation. In an outdoor installation, the recloser could simply be mounted above the capacitor bank, with minimal changes to the existing installation. By using reactors in series with the capacitors, switching transients can be minimised to ensure safe operation of the recloser.

All NOJA Power reclosers are connected to RC-10 controllers allowing for communications back to a SCADA master station. A variety of communication protocols are supported for control and interfacing with NOJA Power reclosers including DNP3, IEC60870-5 and IEC61850. Network operators can easily connect or disconnect the capacitor bank from the substation through a remote command from the SCADA master station, or by using the logic functionality or protection capabilities of the RC-10 Controller.

It is possible to extend the basic capacitor switch application to create a switched capacitor bank by using multiple NOJA Power Reclosers and capacitor banks. Switched capacitor banks allow the capacitance to be varied in a number of stages as required, in order to control the reactive power flow through the network. This is achieved by connecting multiple capacitor banks together, each with a NOJA Power Recloser. The total capacitance can be controlled by opening and closing the desired reclosers.

Switched capacitor banks are useful in locations where there is large variation in the reactive power, such as at the connection points for various forms of renewable energy generation. By using the inbuilt protection and logic functionality of the RC-10 Controller or NOJA Power’s Smart Grid Automation application, advanced automation schemes can be created to automatically control all NOJA Power reclosers in the switched capacitor bank.

A four stage switched capacitor bank was installed at a hydroelectric power plant in Colombia. The switched capacitor bank was made from four individual capacitor banks connected in parallel, each controlled by a NOJA Power Recloser. Reactors are still required for the capacitors connected to each phase in each capacitor bank in order to prevent overvoltage conditions during switching.

With this capacitor switching application, NOJA Power has once again demonstrated the versatility of NOJA Power reclosers and the RC-10 Controllers, establishing why they are world class market leading products. This application is just one of the ways that NOJA Power is fulfilling the vision of being a world leader in medium voltage pole mounted switchgear. With the vast array of internal protection functions, communication protocols, and the Smart Grid Automation features, NOJA Power Reclosers can be implemented to meet a range of needs in complex power networks across the globe.