In commercial and industrial LED lighting, drivers historically were isolated using transformers to step-down voltage, however there is increasing use of non-isolated drivers.
Understanding Isolated Drivers
An isolated driver is an electrical device that employs a transformer to step down high voltage to a lower one, which is then rectified into DC output. The term “isolated” stems from the fact that the primary coil (high voltage) and secondary coil (low AC voltage output) of the transformer are not directly connected.
Non-Isolated Drivers Explained
A non-isolated driver directly connects the load terminal to the input terminal without using a transformer for voltage reduction. This type of driver introduces high AC voltage directly to the load terminal.
Key Differences
Safety Considerations
Isolated drivers are generally considered safer due to the separation between high-voltage input and low-voltage work area, reducing the risk of electric shock. Non-isolated drivers, however, transmit high voltage directly to the working area terminal, presenting some higher risk of electric shock.
Safety measures for non-isolated drivers:
- Proper connection of Class I grounding with the power supply system
- Greater voltage protection of aluminum substrates (up to 3 KV)
Efficacy
Non-isolated drivers generally offer higher efficiency, leading to better luminaire efficacy compared to isolated drivers.
Luminaire Lifetime
Isolated drivers provide better protection against power surges and spikes, which can extend the life of LED components. The electrical isolation helps prevent high voltage from directly reaching the LED board, reducing the risk of damage.
Cost
Isolated drivers typically cost more due to their more complex AC/DC flyback circuit structure, which allows for multiple outputs. Non-isolated drivers use simpler DC/DC boost or step-down buck circuits, resulting in lower costs. Therefore, non-isolated drivers can lower luminaire first costs, as well as lower operating cost, due to their higher efficacy. Potentially longer isolated driver lifetime can also potentially impact costs. Overall, there are some complex cost trade-offs, with non-isolated drivers better for first costs and energy costs, but isolated drivers potentially better for luminaire lifetime.
Market Trends and Manufacturer Practices
The market has increasingly accepted non-isolated drivers as production technology has matured. Some manufacturers offer both isolated and non-isolated driver solutions in their product lines. Some manufacturers also provide customization options, allowing customers to request isolated drivers or non-isolated ones, based on specific requirements.
When choosing between isolated and non-isolated LED drivers, consider the trade-offs between safety, efficiency, lifetime, and lifecycle costs. While isolated drivers offer enhanced safety and better protect luminaire lifetime, non-isolated drivers provide lower costs and higher efficiency. The choice ultimately depends on the specific application and safety requirements of the lighting project.
Image: https://www.youtube.com/watch?v=l7reLq-y8-k
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