Introduction
When it comes to safeguarding AC and DC equipment against transient voltage surges, correctly sizing surge protection devices (SPDs) is crucial. This article explores the process of correctly sizing SPDs for the protection of AC and DC equipment, To illustrate practical examples, we will refer to the datasheets of a fictional manufacturer, XYZ Surge Protection.
- Sizing Surge Protection Devices for AC Equipment:
When sizing SPDs for AC equipment, several factors must be considered. Begin by assessing the AC system’s requirements, including the maximum system voltage, load characteristics, and expected surge levels. Referring to the datasheet of XYZ Surge Protection’s AC SPD models can provide guidance on the appropriate specifications. - Voltage Protection Level (VPL) Selection:
The voltage protection level, also known as the let-through voltage, is a critical parameter in sizing SPDs. It represents the maximum voltage allowed to pass through to the protected equipment. Referring to the SPD datasheet, the VPL values for both the AC-123 and DC-456 SPDs can be found. For instance, the AC-123 SPD datasheet states a VPL of 1.5 kV for AC equipment, while the DC-456 SPD datasheet specifies a VPL of 800 V for DC equipment. - Nominal Discharge Current (In) Calculation:
To ensure effective surge protection for AC equipment, calculating the nominal discharge current (In) is essential. The In rating represents the SPD’s ability to handle surge currents without compromising its performance. The datasheet of XYZ Surge Protection’s AC SPDs offers guidance on calculating the In based on factors such as lightning flash density and the presence of additional lightning protection measures. - Coordination with AC Equipment:
Proper coordination between the SPD and AC equipment is crucial for comprehensive surge protection. Analyze the AC system’s topology, identify potential surge paths, and strategically position the SPDs at critical points to divert surges away from sensitive equipment. XYZ Surge Protection’s datasheet provides insights on coordination and installation guidelines for AC equipment. - Sizing Surge Protection Devices for DC Equipment:
Sizing SPDs for DC equipment involves similar considerations. Begin by assessing the DC system’s requirements, including the maximum system voltage, load characteristics, and expected surge levels. The datasheet of XYZ Surge Protection’s DC SPD models can serve as a valuable reference for proper sizing. - Voltage Protection Level (VPL) Selection:
Selecting the appropriate VPL for DC equipment is crucial in surge protection. Consult the datasheet of XYZ Surge Protection to determine the suitable VPL for DC applications, considering the sensitivity of the equipment and the surge environment. - Nominal Discharge Current (In) Calculation:
Calculating the In rating for SPDs protecting DC equipment is essential for reliable surge protection. Refer to XYZ Surge Protection’s datasheet to calculate the In based on factors such as the DC system’s exposure to potential surges and the presence of any additional protection measures. - Coordination with DC Equipment:
Coordinate the placement of SPDs with DC equipment to ensure comprehensive surge protection. Consider the DC system’s topology, identify potential surge paths, and position SPDs strategically to redirect surges away from sensitive equipment. XYZ Surge Protection’s datasheet provides installation guidelines and coordination insights for DC equipment.
Practical Example
To give a practical example. Consider this scenario.
It is required to size the SPD for the TINSE Simplicity 3KVA Hybrid Inverter against transient voltage surges, it is crucial to accurately size surge protection devices (SPDs). This exercise focuses on sizing SPDs using Schneider’s Acti 9 series and provides examples of suitable Acti 9 models for specific specifications. The AC input voltage of the TINSE Simplicity 3KVA Hybrid Solar Inverter to be protected is 220 V AC, and the maximum input voltage of the charge controller is 75 V DC.
- Sizing Surge Protection Devices for AC Equipment:
When selecting SPDs for AC equipment, Schneider’s Acti 9 series offers a range of options. For our example, we will consider the Acti 9 iPRC 40kA SPD. This model is specifically designed for AC applications and provides robust surge protection up to 40 kA. It offers a suitable voltage protection level (VPL) for AC equipment operating at 220 V AC, ensuring efficient surge suppression and protection.
- Sizing Surge Protection Devices for DC Equipment:
To protect the inverters’ charge controller, Schneider’s Acti 9 series includes SPDs designed specifically for DC applications. In this case, we can choose the Acti 9 iPRC DC 60 V SPD, which offers reliable surge protection for DC systems. With a maximum voltage rating of 60 V DC, it is well-suited to protect devices operating within the 75 V DC maximum input voltage range of the charge controller. - Coordination and Installation:
To ensure comprehensive surge protection, coordination and proper installation of SPDs are crucial. Follow Schneider’s Acti 9 installation guidelines to determine the optimal placement of the selected SPDs. Usually, the SPD is installed in parallel to the equipment being protected. - Compliance with Standards:
When sizing SPDs, it is important to adhere to industry standards to ensure proper protection. Schneider’s Acti 9 SPDs comply with relevant international standards, such as IEC 61643-1 and UL 1449, providing confidence in their performance and reliability. Following these standards ensures that the selected Acti 9 SPDs meet the necessary requirements for protecting AC and DC equipment.
Conclusion:
Accurate sizing of surge protection devices is essential for effectively safeguarding AC and DC equipment against transient voltage surges. Schneider’s Acti 9 series offers a range of options suitable for different applications. For AC equipment protection at 220 V AC, the Acti 9 iPRC 40kA SPD is recommended, while for DC equipment protection with a maximum input voltage of 75 V DC, the Acti 9 iPRC DC 60 V SPD is suitable. By coordinating the placement of these SPDs and following installation guidelines, comprehensive surge protection can be achieved. Remember to consult professionals and adhere to industry standards to ensure optimal protection for AC and DC equipment using Schneider’s Acti 9 series.
