[A typical grid power system protection for high voltage

Power System Protection Aiding Grid System Distribution & Control

Electricity is needed for almost everything we do. However, the rising demand for power from consumers coupled with limited power generation sources have led engineers to focus more on electrical power grid stability. Understanding the basics of power system protection can help engineers prevent catastrophic power failures.

Grid Power System Protection: An Overview

Electrical grid protection is imperative for mitigating power imbalance problems which can cause equipment damage, lead to fires, and/or threaten the safety of individuals. The following diagram represents a typical power system protection model.

A typical power system protection model

The image shows a basic level protection system for a transmission line with different elements, including a:

  • Circuit breaker (CB)
    A circuit breaker is an electrically operated switch capable of safely making or breaking electrical contact during short circuit conditions. It typically acts as a closed circuit and allows the current to pass through the line under normal conditions. Under abnormal conditions, an associated relay sends the signal and the circuit breaker becomes an open circuit, interrupting the fault to travel further.
  • Current and potential transformers (CT and PT)
    Current and potential transformers reduce high currents and voltages to levels where relay circuits can handle them with ease. The former converts high amperage to the standard output of 1 or 5 amperes. On the other hand, potential transformers reduce high voltage to a standard low voltage of 110V for protective relays.
  • Relay
    A relay consists of both a high and low voltage system separated by a magnetic coil. The high-voltage side acts as a switch to operate circuit breakers. In case of a fault, the low voltage side is activated and sends a DC current through the magnetic coil. The coil now creates a magnetic field that helps close the switch on the high-voltage side. As a result, the circuit breaker trips and the faulty current is sent to the ground.

Apart from these basic power system protection elements, a number of other electronic components are commonly used in the line to offer protection against surge voltages. Power system protection electronics and circuit boards often are comprised of Zener diodes, decoupling capacitors, varistors, triacs, and other switching components. And to be effective, these PCBAs must be adequately grounded as this is the primary method for eliminating unwanted energy from the system.

Requirement of Grounds

Grounding is critical when designing and developing power system protection boards.

There are three types of grounds in PCBA design:

  • Earth ground: earthing of neutral wire to direct any fault currents to the ground
  • Chassis ground: grounding the chassis of a certain device to keep users safe in case of accidental contacts
  • Signal ground: a reference point necessary for the propagation between components and external circuitry

Furthermore, there are three PCB grounding configurations to accommodate the aforementioned PCB ground types:

  • Ground plane(s): a large sheet of copper that functions as a grounding route for components on single-layer boards
  • Ground layer(s): connects vias to the dedicated ground plane in multilayer PCBs
  • Ground trace(s): all groundings are routed through a common trace

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Important High-Voltage Protection Board Design Considerations

In the event of voltage spikes, a large potential difference may occur between any two conductors on the PCB board. If the potential difference is strong enough to break air insulation, or if the clearance has been reduced by debris, arcs may develop, leading to short circuits between the components followed by board failure. Here are some high-voltage PCB design considerations to follow:

  • Optimize creepage and clearance distances as per IEC 60950-1 and/or UL-60950-1 standards.
  • Consider elliptical or circular pads over rectangular pads to ensure more clearance.
  • Select HV PCB materials and substrates to ensure proper safety.
  • Apply the best surface finish to protect boards from debris.
  • Apply conformal coating to protect the board from thermal stress caused by overvoltages and contaminants from harsh environments.

For reliable deployment and operation, designers must overcome certain challenges during the early phase of grid power system design. Regulatory protocols should be strictly followed to ensure your board meets the desired performance criteria. Components must align with correct placement standards, which may otherwise severely affect the board’s functionality during a high-voltage surge. Moreover, consider using a quality management system to ensure boards are free from any design errors and functionality issues.

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Tempo Automation specializes in PCBA turnkey manufacturing for prototyping and low-volume production. Our highly advanced digital thread process acknowledges grounding issues during DFM and suggests necessary changes for faster bringup.

Tempo employs a white-box turnkey PCBA manufacturing process that promotes collaboration and transparency between engineers and CMs. This allows us to quickly deliver high-quality boards for both standard and non-standard designs that meet energy industry criteria for prototyping and on-demand production. We also provide downloadable DRC files in Altium Designer, Cadence Allegro, Mentor Pads, other CAD formats, and Excel.

If you are ready to have your design manufactured, try our quote tool to upload your CAD and BOM files. If you want more information on how we can help you meet power system protection requirements, contact us.

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