PV DC SPD
The core feature of the photovoltaic direct current overcurrent protector lies in that it is specially designed for the special working condition of the DC side of the photovoltaic system without zero-crossing points. It adopts special arc extinguishing technology and thermal trip device to forcibly extinguish the DC arc, ensuring safety. In terms of selection, its maximum continuous working voltage (Uc) must be higher than the system rated voltage (Un) to cope with voltage fluctuations caused by changes in light intensity, and strictly follow specific standards such as IEC 61643-31. The product adopts a modular plug-in design and features high-energy varistor (MOV) technology, nanosecond-level response speed, thermal protection, failure indication, etc. In addition, it needs to adapt to the harsh outdoor environment of to provide reliable protection at key positions such as the combiner box and inverter.
PV DC SPD
The photovoltaic DC surge protector (SPD) is a protection device specifically designed for photovoltaic (PV) systems. Compared with ordinary surge protectors, it has significant differences in electrical performance, safety standards, and application environments.
PV DC SPD->DC Power SPD
Un(V) :
DC600V/1000V/1200V/1500V
Uc(V) :
DC670V/1200V/1500V/1800V
In (8/20 μs):
20kA
Imax(8/20 μs):
40kA
Reference Standards:
IEC 61643-31OEM/ODM Acceptable
Additional Function:
Thermal Tripping Protection, Status Indicator, and Remote SignalingWhat is Surge Protective Device?
A surge protective device, also known as a surge protector or SPD, is designed to safeguard electrical components against surges in voltage that might happen in the electrical circuit.
Whenever a sudden increase in current or voltage is produced in the electrical circuit or communication circuit as a consequence of outside interference, the surge protection device may conduct and shunt in a very short period of time, preventing the surge from damaging other devices in the circuit.
Surge protective devices (SPDs) are a cost-effective method for preventing outages and enhancing system reliability.
They are typically installed in the distribution panels and play an important role in ensuring the smooth and uninterrupted operation of electronic devices in a wide range of applications by limiting transient overvoltage.
How Does Surge Protective Device Work?
The basic principle behind SPDs is that they provide a low impedance path to ground for excess voltage. When voltage spikes or surges occur, SPDs work by diverting the excess voltage and current to the ground.
In this way, the magnitude of the incoming voltage is lowered to a safe level that doesn't damage the attached device.
To work, a surge protection device must contain at least one non-linear component (MOV or GDT), which under different conditions transitions between a high and low impedance state.
Their function is to divert the discharge or impulse current and to limit the overvoltage at the downstream equipment.
Surge protection devices function under the three situations listed below.
A. Normal Condition (absence of surge)
In case of no surge conditions, the SPD has no impact on the system and acts as an open circuit, it remains in a high impedance state.
B. During voltage surges
In case of voltage spikes and surges, SPD moves to the conduction state and its impedance decreased. In this way, it will protect the system by diverting the impulse current to the ground.
C.Back to normal operation
After the overvoltage has been discharged, SPD shifted back to its normal high impedance state.
SOLUTIONS
Experimental Facilities
Cresin is equipped with professional-level surge protection device (SPD) comprehensive performance testing equipment, which can fully adapt to the performance testing and trial research of all categories of T1 and T2 level power surge protection devices.
Large constant temperature and humidity equipment
High current generator equipment
RF network analyzer
PV DC SPD Operating Principle
Normal high-resistance open circuit; during surge, it instantly conducts and discharges the current, limiting the voltage; after failure, it quickly mechanically disconnects, cutting off the continuous DC arc and preventing the junction box from catching fire.
Normal operating condition (no lightning)
Basic structure
Core components: Zinc oxide varistor (MOV) + thermal trip-off device + short-circuit protection. The circuit provides protection for both DC positive and DC negative poles with ground.
The DC photovoltaic circuit maintains a high DC voltage of 1000V/1500V for a long time.
The varistor exhibits extremely high insulation impedance, with only microampere-level leakage current, almost not consuming electrical energy, equivalent to an open circuit, and does not affect the normal photovoltaic power generation.
When lightning overvoltage arrives
The lightning induction generates a transient high voltage, exceeding the threshold voltage of the varistor:
The varistor instantly changes from high resistance to low resistance, discharging the large current of the lightning to the ground, clamping the line voltage to a safe level, and protecting the DC module of the inverter from being broken down.
FAQ
What is the difference between PV DC SPD and ordinary DC SPD?
PV DC SPDs are specifically designed for photovoltaic systems with high DC voltage, outdoor exposure, and special fault conditions. Ordinary DC SPDs may not be suitable for PV applications unless they are tested and rated for PV systems.
How do I select the voltage rating of a PV DC SPD?
The voltage rating should be higher than the maximum open-circuit voltage of the PV string under the lowest expected temperature. Common options include 600V, 1000V, 1200V, and 1500V DC.
Where should PV DC SPDs be installed?
PV DC SPDs should be installed in PV combiner boxes, near inverter DC inputs, and in DC distribution cabinets. For long cable runs, SPDs may be needed at both the PV array side and inverter side.
Why does the DC side of a PV system need surge protection?
What is a PV DC SPD?
A PV DC SPD is designed to protect the DC side of a photovoltaic system from surge voltage. It is usually installed between the PV strings and inverter, or inside PV combiner boxes.
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