Bourns Announces High-Performance AC/DC Surge Protective Device Families
The new devices come equipped with unique precautions to prevent thermal runaway. This article wille examine surges for AC and DC circuitry and look deeper at the two families from Bourns.
To ensure safety and compliance in any electronic circuit design, protection from power surges is a necessity. Especially in high-power electronics like energy generation, EV charging, and battery storage systems where failures could be catastrophic, surge protection is a critical design consideration for any engineer.
Image used courtesy of Adobe Stock
Recently, Bourns released two families of surge protective devices: one for AC circuits and one for DC circuits. While both devices share similarities in operation and form factor, there are notable differences between the two.
AC Vs. DC Surges
A surge, or transient voltage, is a sudden increase in voltage that significantly exceeds the designated level in a circuit. In both AC and DC circuits, surges can be harmful to electronic devices and systems, potentially causing damage or failure. However, the nature and impact of these surges can differ between the two due to their inherent characteristics.
A DC versus AC waveform. Image used courtesy of Matsusada Precision
In AC circuits, the voltage oscillates between positive and negative values, typically in a sinusoidal waveform. A surge in an AC circuit can occur due to various reasons, such as lightning strikes or switching heavy loads. Hence, surge protection devices for AC circuits are designed to handle these sudden increases in voltage and protect the connected devices.
In DC circuits, the voltage is constant and does not alternate. However, surges can still occur due to reasons like lightning strikes or rapid changes in load current. The impact of a surge in a DC circuit can be more damaging because the voltage does not naturally fall back to zero as it does in an AC circuit. Therefore, surge protection in DC circuits is crucial and often involves devices that can absorb the surge energy and protect the circuit components.
AC Surge Protectors
The first of the two surge protective families launched recently from Bourns is for AC devices.
The Bourns Model 1250A Series is general-duty surge protective devices (SPDs) meant to protect branch panels and high-risk electrical service entrances. Intended to be installed in the main switchboard near sensitive terminals, the devices come in a DIN Rail pluggable/replaceable format.
Diagram of the 4P family offering. Image used courtesy of Bourns
Rated for surges up to 50 kA, the devices are UL-recognized Type 4, Type 2 Location SPDs, passed short circuit current ratings up to 200 kArms without external fuse, and feature a maximum operating voltage rating of up to 690. Notably, the device also features a unique advanced thermal disconnector (TD+) feature, which has a self-extinguishing mechanism to reduce the risk of fire after a catastrophic event.
DC Surge Protectors
Following the launch of their AC line of surge protective devices, Bourns also announced the launch of a line of DC surge protective devices.
The Model 1420A Series is designed to protect power systems, such as photovoltaics systems and EV chargers, from damage from lightning, transients, and power surges. To do this, the device is rated for a network voltage of 1500 VDC, has a UL voltage protection rating of <4.0 kV, and has a short-circuit current rating of 50 kA. For ease of installation, the device comes in a DIN Rail mountable SPD design with pluggable/replaceable modules.
Electrical diagram of the 1420A series. Image used courtesy of Bourns
Like the 1250A family, the 1420A family also features a dedicated advanced thermal disconnector. Additionally, the family comes with an additional window fault indicator which enables the external monitoring of the device’s status.
