Learn the basic definition of high voltage connectors.
Explore pressing challenges in high voltage connector design.
Improve safety and compliance with reliable tips for working with high voltage connectors.
High voltage connectors for electrical systems
High voltage connectors are a common feature in the medical, automotive, manufacturing, and communication fields. Unlike their low voltage counterparts, high voltage connectors pose considerable challenges to hardware engineers. You can’t afford mistakes in high voltage designs, as they could lead to safety and fire risks.
What Are High Voltage Connectors?
High voltage connectors refer to interconnects that channel electrical current beyond a certain voltage limit. The IEC defines high voltage as voltages above 1,000 VAC or 1,500 VDC. However, it is a mistake to categorize high voltage connectors purely with IEC standards.
A connector is considered high voltage if it conducts electrical current that poses safety risks to humans or triggers electric arcs. For example, an electrical current beyond 50V may trigger a sudden increase in heart rate. Connectors carrying 120V can cause arcing when the conductors are near to each other.
You’ll find high voltage connectors in various shapes and sizes. For example, they are available as single pins, multi-pins, in-line, and panel mounts. Some applications that use high voltage connectors operate in harsh environments such as extreme temperature or pressure.
High Voltage Connector Design Challenges
You must approach high voltage connectors with a different perspective from low voltage designs. At a higher voltage, the mechanical composition, operating environment, and design of the connectors might trigger the following issues.
Corona discharge happens when the surrounding air around the high voltage conductors is highly charged and ionized. This phenomenon can happen for voltages as low as 300V. Corona discharge leads to the formation of a conductive region between the high voltage conductor and adjacent pins.
While corona discharge does not cause arcing, it leads to the gradual degradation of the dielectric in the insulator. You’ll also want to pay attention to the connector geometry, as corona discharge is more prevalent in insulators with air gaps. Corona discharge might cause safety hazards after the product is deployed.
Arcing is an immediate repercussion when two highly charged conductors are placed in close proximity. In high voltage conductors, arcing happens when the electrical stress breaks down the molecular structure of a dielectric. When the insulator fails, current flows between the high voltage conductor to the ground and results in electrical sparks. Even if the electrical arc is not destructive, it may cause electromagnetic interference (EMI) to adjacent circuits.
Design Considerations for High Voltage Connectors
PCB-mounted high voltage connectors
The risks of fire hazards and safety is real when it comes to high voltage connector designs. As such, you’ll want to take the following design suggestions into consideration when working with high voltage connectors.
As high voltage can compromise insulators, you’ll want to choose a connector that is made with dielectric with high electrical strength. For example, PTFE and silicone rubber are more resistant to electrical breakdown. Also, it is important that the insulator does not have a porous surface to prevent corona discharge.
Creepage and Clearance
Creepage refers to the shortest distance between conductors along the insulator while clearance is the shortest path between conductors along with the air. Both parameters are important to prevent arcing and corona discharge. When choosing a connector, ensure that it has sufficient creepage and clearance for the designated voltage.
The presence of foreign particles and water moisture in the air can aggravate arcing and corona discharge. Even if you are using a connector that works reliably in the lab environment, you can’t assume the same degree of safety when deployed. High voltage connectors are classified according to their pollution degree, which ranges from 1 to 4. If you are deploying the product in a polluted environment, you will need to use a connector with a higher pollution degree to comply with safety standards like UL and IEC.
Ensuring safety in high voltage designs doesn’t stop at choosing the right connectors. In an electronics product, the PCB layout becomes an important factor in ensuring the safety and reliability of the circuit. Here are a few basic rules to adhere to when designing with high voltage connectors or terminal blocks on a PCB:
- Ensure a sufficient clearance between the high voltage and adjacent traces.
- Avoid sharp edges on the high voltage trace to prevent arcing.
- Incorporate safety measures, such as a fuse, in case of a short circuit.
- If the trace also carries a high current, ensure that it has sufficient thickness and width.
Cadence offers design and analysis tools that can help you strike the balance between functionality, safety, and manufacturability. Our software allows you to specify rules and constraints to meet the stringent standards of high voltage connector designs in electronics products.
If you’re looking to learn more about how Cadence has the solution for you, talk to us and our team of experts.