About surge protective devices Standard——IEC/EN 61643
IEC 61643 is a series of international standards developed by the International Electrotechnical Commission (IEC). These standards define the requirements and testing methods for surge protective devices (SPDs) used in low-voltage power systems, telecommunications, and signal networks.
The purpose of these standards is to ensure the safety, performance, and reliability of SPDs when protecting electrical equipment from overvoltage surges caused by lightning strikes or switching operations.
About IEC/EN 61643：
IEC/EN 61643-11:
Low-voltage surge protective devices – Part 11: Surge protective devices connected to low-voltage power systems – Requirements and test methods
IEC/EN 61643-12:
Low-voltage surge protective devices – Part 12: Surge protective devices connected to low-voltage power systems – Selection and application principles
IEC/EN 61643-31：
Low-voltage surge protective devices – Part 31: Requirements and test methods for SPDs for photovoltaic installations
IEC/EN 61643-32：
Low-voltage surge protective devices – Part 32: Surge protective devices connected to the d.c. side of photovoltaic installations – Selection and application principles
IEC/EN 61643-21:
Low voltage surge protective devices – Part 21: Surge protective devices connected to telecommunications and signaling networks – Performance requirements and testing methods
IEC/EN 61643-22:
Low-voltage surge protective devices – Part 22: Surge protective devices connected to telecommunications and signalling networks – Selection and application principles
What are the differences between Listed and Recognized Types of Surge Protective Devices (SPDs) in UL 1449?
The SPD Types described below are in accordance (paraphrased from) with UL 1449
Third Edition, as follows:
Type 1 SPDs (Listed) – Permanently connected, hard-wired SPDs intended for installation between the secondary of the service transformer and the line side of the main service equipment overcurrent protective device, as well as the load side of the main service equipment.
Type 1 SPDs include watt-hour meter socket enclosure type SPDs. Being on the line side of the service disconnect where there are no overcurrent protective devices to protect an SPD, Type 1 SPDs must be listed without the use of an external overcurrent protective device. The Nominal Discharge Current Rating for Type 1 SPDs is either 10kA or 20kA.
Type 2 SPDs (Listed) – Permanently connected, hard-wired SPDs intended for
installation on the load side of the main service equipment overcurrent protective device.
These SPDs may also be installed at the main service equipment, but must be installed on the load side of the main service overcurrent protective device. Type 2 SPDs may or may not require an overcurrent protection device per their NRTL listing. If a specific overcurrent protection is required, the SPD’s NRTL listing file and labeling/instructions are required to note the size […]
Selectivity between overcurrent protective device (OCPD)
Understanding OCPD Selectivity: What Is OCPD Selectivity?
Selectivity refers to the proper coordination between overcurrent protective devices so that only the affected device trips during a fault, leaving other parts of the system operational.
If one or both of OCPD is a circuit breaker, then their tripping characteristics must be compared with each other or with fuse characteristics,
If Upstream circuit-breaker and downstream fuse
Selectivity is obtained by comparing time-current characteristics.
It is advisable to maintain a safety margin between the maximum tripping time of the fuse characteristic and the minimum tripping time of the circuit-breaker characteristic.
Generally, a delta time ≥ 1s is enough for thermal-magnetic breakers and 100 ms in case of electronic trip units.
More selectivity technical issue please refer to OCPD device manufacture’s manual
Prosurge’s SPD overcurrent protective device -SCB
PROSURGE SCB provides backup over-current protection for the SPD, which is fully coordinated with the surge protective device according to the choice of different models.
Comparing to normal backup circuit breaker/fuse, the PROSURGE SCB achieve a better balance between surge withstand performance (no tripping while expected surge occurs) and sharp reaction against short circuit and abnormal leakage current.
Comparison […]
Parallel vs. Series Connection for SPDs: Which Is Better?
When selecting between parallel or series connection methods for surge protectors (SPDs), the decision should be based on specific application scenarios and requirements. Both parallel and series connections are common configurations, each offering distinct advantages and suitable applications.
Parallel Connection
In a parallel configuration, multiple SPDs are connected simultaneously to the power lines of the protected equipment. This approach provides:
1.Higher current capacity and lower grounding resistance
2.Better distribution and mitigation of lightning surges
3.Enhanced overall lightning protection for the system
4.Redundancy and failover capability: If one SPD fails, others continue to protect the equipment.
Series Connection
In a series configuration, multiple SPDs are connected sequentially along the power lines. This method offers:
1.Higher voltage withstand capability for high-voltage scenarios
2.Cascaded protection, where each SPD handles a portion of the surge energy
Factors to Consider When Choosing Between Parallel and Series Connections
Applications for Parallel Connections
1.Low-voltage power systems
Parallel-connected SPDs are commonly used in low-voltage systems to share surge energy and protect equipment from lightning damage.
2.Communication systems
Multiple SPDs are often installed on telephone or network lines to shield communication devices.
3.Voltage-sensitive electronics
Parallel configurations protect sensitive equipment like computers and servers by optimizing surge energy distribution.
Applications for […]
Understanding SPD Failure Modes: Open-Circuit vs. Short-Circuit and Their Impact on System Protection
Surge Protection Devices (SPDs) are critical components in safeguarding electrical systems from voltage spikes and surges. However, like any other device, SPDs can fail. Understanding the failure modes of SPD open-circuit and short-circuit—is essential for ensuring continuous protection and system reliability.
Open-Circuit Failure in SPDs
Open-circuit failure is a common mode of failure in SPDs, particularly those with varistors. This type of failure typically occurs due to the natural ageing process or thermal protection mechanisms. When an SPD reaches the end of its life, an internal disconnector is activated, rendering the SPD inoperative. This disconnector is designed to disable the SPD to prevent further damage.
In SPDs with gas discharge tubes, internal disconnectors (thermal protection) may also be used to protect against abnormal overheating caused by unexpected follow currents or surge currents. It’s important to note that thermal runaway, a common cause of failure in varistor-based SPDs, does not apply to SPDs with gas discharge tubes or encapsulated spark gaps.
A spark gap, another type of SPD, may fail in an open-circuit mode when it can no longer ignite an arc due to electrode wear or a faded electronic ignition circuit. In this state, the SPD becomes permanently open, leaving the system […]
What is Iimp—Iimp of Class I SPD
impulse discharge current for class I test imp
The impulse discharge current passing through the device under test (SPD) is defined by the crest value Iimp, the charge Q and the specific energy W/R. The impulse current shall show no polarity reversal and shall reach Iimp within 50 µs. The transfer of the charge Q shall occur within 5 ms and the specific energy W/R shall be dissipated within 5 ms.
The impulse duration shall not exceed 5 ms
Preferred values of impulse discharge current Iimp for class I SPD Iimp：1，2，5，10， 12,5，20 and 25 kA
specific energy for class I test W/R
energy dissipated by a unit resistance of 1 Ώ with the impulse discharge current Iimp
NOTE：This is equal to the time integral of the square of the current (W/R = ∫ i 2 d t).
Q (As) and W/R (kJ/W) for given values of Iimp (kA).
Q = Iimp × a， where a = 5 × 10-4 s
W/R = Iimp2 x b， where b = 2.5 × 10-4 s
The IEC 62305 standard, defines “protection levels” as specific categories of lightning protection systems, each designed to provide a […]
Why you choose Prosurge– About PROSURGE SPD technology
①High energy MOV technology
Voltage limiting type SPD per IEC 61643
High energy AC/DC MOV is employed for PROSURGE’s class I, Class II and Class III AC/DC/PV SPD with compact size.
Advantage of MOV (Metal oxide varistor)
*Higher lightning & surge current discharge capacity
*Wide voltage range to cover AC/DC/PV application
*Fast response
*Wide working temperature
*No follow current in case of surge events
*End of life through thermal runaway, make thermal protection possible
*Stable performance in a long period time.
*Compact size
*Not influenced by various environmental factors while well encapsulated, especially suitable for application in higher altitude，offshore(e.g. offshore windfarms), dust, hot and moisture circumstances
The heat generated by a MOV in end-of-life conditions can be sufficient to cause dangerous overheating of the SPD and even cause the SPD to catch fire.
To keep the SPD and system protected safe, thermal protection is used in all PROSURGE’s MOV type SPD
②PROSURGE patented thermal protection technology
√ Fast response to abnormal heat of MOV body
√ Surge withstand coordination with the SPD surge rating
√ Fast disconnect and cutoff the circuit in case of SPD failure
③PROSURGE patented arc-extinguish technology
Because of an arc between contact may happen while thermal disconnector open, even the arc current lasts for a short time, that […]
the selection and installation of photovoltaic surge protectors
Photovoltaic power generation is another renewable clean energy besides wind power generation, and is widely used in various countries and regions. It has the characteristics of simple installation, scalability, stability, and long life. Lightning strikes and surges are also a major disaster for photovoltaic power generation systems. Prosurge provides a comprehensive and efficient lightning protection solution for photovoltaic power generation systems.
PV installation with an external LPS when the separation distances is maintained (excluding multi-earthed solar systems, such as PV power plants)
Class II/T2 PV SPD is suggested to used at DC side of invertor
PV installation with an external LPS when the separation distances is maintained (excluding multi-earthed solar systems, such as PV power plants)
Class II/T2 PV SPD is suggested to used at DC side of invertor
PV installation with an external LPS where the separation distances can not be maintained (including multi-earthed systems, such as PV power plants)
Class I/T1 PV SPD is suggested to used at DC side of invertor
Surge protective device – do you know its types?
Surge Protection Device (SPD) is an electronic device that provides safety protection for various electronic devices, instruments, and communication lines. It is suitable for power supply systems with AC 50/60Hz and rated voltage of 220V/380V. The types and structures of surge protectors vary according to their different uses, but they can generally be classified in the following ways:
一、 Classified by working principle
- Voltage switch type: It is in a high impedance state when there is no instantaneous overvoltage, and suddenly changes to a low impedance state when a surge occurs, effectively diverting the surge current to ground and protecting the equipment from overvoltage damage. Commonly used nonlinear components include discharge gaps, gas discharge tubes, thyristors, etc.
- Voltage limiting type: It exhibits a high impedance state when there is no surge, but as the surge current and voltage increase, the impedance will continuously decrease, limiting the voltage to a safe level. Its current voltage characteristics are strongly nonlinear, thus avoiding damage to equipment caused by overvoltage. Commonly used nonlinear components include zinc oxide, varistors, suppression diodes, avalanche diodes, etc.
- Combination type: Combining voltage switch type and voltage limiting type SPDs together, it has both voltage switch function […]
Do you know the Up value of surge protectors?
Surge protectors, as an important protective device, play a crucial role in protecting equipment from surge currents. When choosing a surge protector, an important parameter is the Up value. So, do you really understand the Up value of a surge protector?
Up: voltage protection level
parameter that characterizes the performance of the SPD in limiting the voltage across its terminals, which is selected from a list of preferred values. This value is greater than the highest value of the measured limiting voltages
After determining the limit of the Up value according to the national standard requirements, according to the standard specification 5.5.3.2 of GB/T 18802.12-2014 Selection and Use Guidelines for Surge Protective Devices in Low Voltage Distribution Systems, the Up value should be equal to or greater than the highest value of the measured limit voltage, and can be selected from the following preferred values:
Preferred values of voltage protection level Up (IEC61643-11)
0.08; 0.09; 0.10; 0.12; 0.15; 0.22; 0.33; 0.4; 0.5; 0.6; 0.7; 0.8; 0.9;
1.0; 1.2; 1.5; 1.8; 2.0; 2.5; 3.0; 4.0; 5.0; 6.0; 8.0 and 10 kV
A small Up value is beneficial for protecting equipment, but it is not necessarily better to have […]