Created by: Glen Zhu | Updated Date: November 19th, 2024
LSP, as a professional surge protective device (SPD) manufacturer, we focus on surge protective device (SPD) products comply to IEC/EN standards.
So we will focus on explaining from the perspective of a surge protective device manufacturer what is the surge protective device (comply to IEC/EN standards) that we understand like?
Note: this article explained the surge protective device (SPD) base on standard IEC/EN 61643, not UL 1449.
There are several parts about what is surge protective device (SPD):
Surge Protective Device (SPD) is an important device used to protect electrical equipment from transient surge impacts. Surges refer to short-term over-voltages or peak currents that exceed normal operating voltages for a moment, usually caused by lightning strikes, equipment switch operations, power system faults and other reasons.
The main function of the surge protector is to limit transient over-voltages, prevent damage to electrical equipment, thereby increasing the service life of the equipment and the reliability of the system.
Standards for surge protective device from a market perspective, there is two main market:
In application of power distribution boards, they can be classified as follows:
More about Differences in Surge Protective Device Classification, Parameters and Test Methods: UL 1449 vs. IEC 61643, visit our webpage https://lsp.global/differences-in-surge-protective-device-classification-parameters-and-test-methods-ul-1449-vs-iec-61643/
Related IEC standards for low-voltage surge protective devices:
Standards | Description |
IEC 61643-01:2024 | Low-voltage surge protective devices – Part 01: General Requirements and test methods |
IEC 61643-11:2011 | Low-voltage surge protective devices – Part 11: Surge protective devices connected to low-voltage power systems – Requirements and test methods |
IEC 61643-12:2020 | Low-voltage surge protective devices – Part 12: Surge protective devices connected to low-voltage power systems – Selection and application principles |
IEC 61643-21:2000+AMD1:2008 CSV | Low voltage surge protective devices – Part 21: Surge protective devices connected to telecommunications and signalling networks – Performance requirements and testing methods |
IEC 61643-22:2015 | Low-voltage surge protective devices – Part 22: Surge protective devices connected to telecommunications and signalling networks – Selection and application principles |
IEC 61643-31:2018 | Low-voltage surge protective devices – Part 31: Requirements and test methods for SPDs for photovoltaic installations |
IEC 61643-32:2017 | Low-voltage surge protective devices – Part 32: Surge protective devices connected to the d.c. side of photovoltaic installations – Selection and application principles |
IEC 61643-41:2024 | Low-voltage surge protective devices – Part 41: Surge protective devices connected to DC low-voltage power systems – Requirements and test methods |
IEC 61643-42:2024 | Low-voltage surge protective devices – Part 42: Surge protective devices connected to DC low-voltage power systems – Selection and application principles |
Related IEC standards for components for low-voltage surge protection:
IEC 61643-311:2013 | Components for low-voltage surge protective devices – Part 311: Performance requirements and test circuits for gas discharge tubes (GDT) |
IEC 61643-312:2013 | Components for low-voltage surge protective devices – Part 312: Selection and application principles for gas discharge tubes |
IEC 61643-321:2001 | Components for low-voltage surge protective devices – Part 321: Specifications for avalanche breakdown diode (ABD) |
IEC 61643-331:2020 | Components for low-voltage surge protection – Part 331: Performance requirements and test methods for metal oxide varistors (MOV) |
IEC 61643-332:2024 | Components for low-voltage surge protection – Part 332: Selection and application principles for metal oxide varistors (MOV) |
IEC 61643-341:2020 | Components for low-voltage surge protection – Part 341: Performance requirements and test circuits for thyristor surge suppressors (TSS) |
Surge Protective Device (SPD) is a critical power protection device, mainly used to limit transient overvoltage and conduct surge current to protect electrical or electronic systems from damage caused by lightning or operational overvoltage and surges.
How do SPD works?
In brief, surge protective device working principle is to guide the overvoltage to the ground through internal nonlinear elements in an instant, thereby avoiding damage to equipment caused by excessive voltage.
To be specific, the working principle of surge protective device is through their internal nonlinear elements such as metal oxide varistors (MOV), gas discharge tubes (GDT), or semiconductor devices (such as TVS diodes). When the voltage exceeds its specified value, it quickly conducts electricity and converts overvoltage into current leakage to ground, thereby limiting the voltage peak at the device end. This design allows surge protective device to divert surges in a very short period of time and avoid damage to other devices in the circuit.
To learn more about surge protective device (SPD) working principle, Please visit https://lsp.global/how-does-surge-protection-work/
The components inside the Surge Protective Device (SPD) mainly include the following: nonlinear elements such as metal oxide varistors (MOV), gas discharge tubes (GDT), or semiconductor devices (such as TVS diodes).
Metal Oxide Varistor (MOV):
MOV is a resistor device with nonlinear volt-ampere characteristics. When the voltage is below a certain value, the MOV is in a high resistance state, almost non-conductive; but when the voltage exceeds this value, the MOV quickly becomes a low resistance state, allowing large currents to pass through, thereby limiting overvoltage to safe levels.
Metal Oxide Varistor (MOV)
Symbol – Metal Oxide Varistor (MOV)
Gas Discharge Tube (GDT):
GDT uses inert gas filled in a sealed tube. When the voltage rises to the breakdown voltage of the gas, gas ionization forms a low-resistance channel to divert surge currents. GDT is usually used for protection against higher energy surges.
Gas Discharge Tube (GDT):
Symbol – Gas Discharge Tube (GDT)
Transient Voltage Suppression Diode (TVS):
TVS diodes are in a high impedance state under normal operating voltages. When the voltage exceeds its breakdown voltage, it quickly conducts and clamps overvoltage to safe levels. TVS diodes are mainly used for protection against low-energy surges.
Transient Voltage Suppression Diode (TVS)
Symbol – Transient Voltage Suppression Diode (TVS)
Key to Symbols used in Basic Circuit Diagrams of Surge Protective Devices
| Symbol | Description |
 | Spark Gap |
 | Horn Gap |
 | Graphite Spark Gap |
| Gas Discharge Tube (GDT) |
| Varistor |
 | Resistor |
 | Fuse |
 | Inductor |
 | Thermal Disconnector |
 | Thermo Dynamic Control |
| Suppressor Diode |
 | Socket and Plug Connector |
Surge protective devices can be classified according to the characteristics of nonlinear elements, mainly into the following types:
Voltage switch type surge protective device:
high impedance when there is no surge, suddenly changes to low impedance when a surge occurs, usually using discharge gaps, gas discharge tubes, silicon controlled rectifiers or bidirectional thyristors.
Limiting voltage type surge protective device:
high impedance when there is no surge, continuously decreases impedance as the surge current and voltage increase, usually using varistors or suppression diodes.
Combination type surge protective device:
composed of voltage switch type elements and limiting voltage type elements with characteristics that change with the added voltage.
Surge protectors can be classified based on installation location and application scenarios as follows:
Power SPD: Used for power system protection, installed at various levels of the power distribution system, such as distribution boxes, control cabinets, etc.
Signal SPD: Used for signal line protection, suitable for communication lines, data lines, video lines, etc.
Combination SPD: Integrates power and signal protection in one device, suitable for scenarios that require both power and signal protection.
Power surge protectors can be categorized into the following types based on their installation location and protected objects:
Type 1 surge protective device: Type 1 SPD, also known as Class I SPD, installed at the service entrance of an electrical system, is designed to withstand high-energy surges, protecting severe transient events for equipment and circuits within the electric system.
Type 2 surge protective device: Type 2 SPD, or Class II SPD, is typically installed downstream from type 1 or at distribution panels. It offers protection against residual surges and lower-energy transients, working in combination with the type 1 surge protective devices.
Type 3 surge protective device: Type 3 SPD, or Class III SPD, is installed at the point of use, near or within significant or sensitive individual devices, providing accurate and localized surge suppression against low-energy surges that is relatively minor but may enough to damage specific equipment as well.
To learn more about Type 1, Type 2, Type 3, Please visist https://lsp.global/spd-type-1-vs-type-2-vs-type-3/
The main equipment for the type test of the surge protective device include:
The surge protective device (SPD) under IEC/EN standards, is a destructive test, or a test of extreme performance.
The main test items of SPD type test include:
Type 1 Test Purpose
Use the Impulse Current Generator (10/350μs) to test SPD, get the value of Iimp, this part is called Type 1 (T1).
Type 2 Test Purpose
Use the Impulse Current Generator (8/20μs) to test SPD, get the value of In and Imax, this part is called Type 2 (T2).
Type 3 Test Purpose
Use the Combination Wave Generator (1.2/50μs & 8/20μs) , get the value of Uoc, this part is called Type 3 (T3).
Thermal Stability Test
Use the AC Thermal Stability Test Device to test SPD, the purpose of the experiment was to check whether the internal disconnector of SPD would misoperate at a non-threatening temperature.
TOV Test
The main purpose of the TOV test for surge protective devices (SPD) is to evaluate their performance and reliability under temporary overvoltage (TOV) conditions. The TOV test simulates temporary overvoltage situations caused by power system faults or operations to verify the protection capability and failure modes of SPDs under extreme conditions, ensuring their safety and effectiveness in practical use.
Operating Duty Test
The main purpose of the operating duty test for surge protective device is to ensure their thermal stability and reliability under operating conditions. The action load test consists of pre-treatment tests and action load tests.
Maximum continuous operating voltage (UC)
maximum r.m.s. voltage, which may be continuously applied to the SPD’s mode of protection.
Impulse discharge current (Iimp) – for class I (Type 1) test
crest value of a discharge current through the SPD with specified charge transfer Q and specified energy W/R in the specified time.
Nominal discharge current (In) – for class II (Type 2) test
crest value of the current through the SPD having a current waveshape of 8/20μs.
maximum discharge current (Imax) – for class II (Type 2) test
crest value of a current through the SPD having an 8/20μs waveshape and magnitude according to the manufacturers specification. Imax is equal to or greater than In.
Open circuit voltage (UOC)
open circuit voltage of the combination wave generator at the point of connection of the device under test.
Voltage protection level (Up)
maximum voltage to be expected at the SPD terminals due to an impulse stress with defined voltage steepness and an impulse stress with a discharge current with a given amplitude and waveshape.
LSP’s wide range of surge protective devices (SPDs) for photovoltaic, energy storage systems, solar farm, cell sites, industrial sites, security systems, water treatment facilities, datacenter etc.
As demand for electricity becomes ever greater, the need to store energy (as well as produce it) also does. Like all electrical installations, energy storage systems need application-specific protection.
Energy Storage Systems (ESS) are now a mature technology. ESS is installed at sites to improve energy management control, such as peak management or frequency regulation, or for renewable energy storage for photovoltaic or wind-generated energy applications.
The importance of such equipment makes interruption of their service unacceptable, so measures must be taken to limit damage due to external influences. One of the risks to be taken into account is possible damage due to transient over-voltages generated by lightning or by switching operations.
The deployment of ESS has demonstrated the limited robustness of these equipment, including battery systems. Specialists in this technology have ascertained that their low impulse voltage withstands (Uw) may lead to critical system failure.
To learn more, please visit https://lsp.global/surge-protection-for-enegy-storage-systems-ess/
Unprotected PV systems will sustain repeated and significant damage in areas where lightning strikes frequently. This can result in a significant repair and replacement costs, system downtime, and revenue loss.
Solar surge protection(SPD) is designed to limit the transient overvoltages and divert the waves of current to the earth. Additionally, it restricts the overvoltage’s amplitude to a value that is safe for the electrical infrastructure and switchgear.
To learn more, please visit https://lsp.global/surge-protection-device-for-solar-application/
A surge protection device (SPD), previously known as a transient voltage surge suppressor (TVSS) is designed to protect electrical systems and equipment from surge events by limiting transient voltages and diverting surge currents.
Industrial SPD, literally speaking, is specially designed to protect machinery in the industrial field. These devices can safeguard machinery and systems in factories and other industrial settings, including telecommunications, control systems, and safety interlock circuits.
Industrial surge protection devices are typically fitted in a panel on a DIN rail mount.
To learn more, please visit https://lsp.global/industrial-surge-protection/
LSP’s reliable surge protection devices (SPDs) are designed to meet the protection needs of installations against lightning and surges. Contact our Experts!
Copyright © 2010-2024 Wenzhou Arrester Electric Co., Ltd. All Rights Reserved. Privacy Policy
