Integrated switchgear system vs discrete components: what's better?
When selecting pole-mounted switchgear, power systems engineers face a choice between integrated systems and discrete components.
Integrated systems are a complete switchgear and control system assembly, including protection relays, instrumentation, SCADA RTUs (supervisory control and data acquisition remote terminal units) and the primary switchgear or circuit breaker.
Discrete systems involve buying separate circuit breakers, relays, RTUs and instrumentation.
While varying degrees of discretisation exist, for this article scope we’ll consider an integrated system as a full primary and secondary system scope from a single manufacturer, and a discrete system where the switchgear and controls are sourced from different manufacturers.
The primary benefit of a discrete system is a high level of customisation, but with the flexibility of modern integrated switchgear systems, the difference is minor.
Conversely, there are many compelling reasons why an integrated switchgear system outperforms discrete components. Here we explore 3 key reasons why that is so.
An integrated switchgear and control system ships from a factory fully tested. The entire system requires no further internal wiring, other than connection to the grid in installation. This offers multiple cost savings. Firstly, the installation procedure requires minimal electrical wiring, reducing the installation cost. Secondly, any manufacturing or wiring issues are identified at the point of manufacture, mitigating the risk of failures at the delivery site during costly outages. Thirdly, the end-to-end testing conducted on the switchgear and control system at the factory mitigates the need for extensive onsite testing.
Devices are shipped with a Routine Test Certificate proving performance, and reducing the site scope of testing to confirmation of settings and checks for transit damage.
Better sensing performance
Unlike discrete systems, which require wiring from the primary switchgear to the control system, integrated switchgear is designed and tested with the entire signal path under control. By controlling the signal path, the electronics design team can adapt the controller performance to the frequency response of the sensors. With the full understanding of the impedance characteristics of the signal path, integrated switchgear designs offer superior sensitivity and precision over discrete selections.
Integrated systems offer advantages in reliability. When the entire switchgear and control system can be built and connected in a clean, factory environment, the system performance improves.
Furthermore, since the entire system is end-to-end tested at the factory, this also improves quality control on the entire installation.
Discrete systems testing is limited by design to functional testing of the scope of the product. A circuit breaker is tested in isolation, generally not with the end installation protection relay. Likewise, protection relays are tested individually, not necessarily in situ with the final switchgear, wiring and terminations.
Integrated products, such as NOJA Power’s OSM Recloser system, are tested both at the module level and at the final system assembly level. This provides additional assurance for product quality and reliability.
To learn more about applications for integrated switchgear solutions, visit www.nojapower.com.au.
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