Experimental Investigation of the Withstand Capability of Class I SPDs under 10/350μs and 8/20μs Impulse Currents
Surge protective devices (SPDs)are required to be tested under impulse discharge currents mainly with waveforms of 8/20 ms and 10/350 ms. However, with the improvement of SPD products, the performance and withstand capability of SPDs under such standard test currents need more investigation. In order to investigate and compare the withstand capability of SPDs under 8/20 ms and 10/350 ms impulse currents, experiments are carried out on three types of typical metal-oxide varistors (MOVs) that are used for class I SPDs. The results show that the MOVs with higher limiting voltage have better withstand capability under 8/20ms impulse current, while the conclusion under 10/350ms impulse current is opposite. Under 10/350 ms current, the MOV failure is related to the absorbed energy per unit volume under single impulse. Crack is the main damage form under 10/350ms current, which can be described as one side of the MOV plastic encapsulation and the electrode sheet peeling off. Ablation of the ZnO material, caused by the flashover between the electrode sheet and ZnO surface, appeared near the MOV electrode.
Surge protective devices (SPDs) connected to lowvoltage power systems, telecommunication and signal networks are required to be tested under requirements of IEC and IEEE […]
Lightning Protection Zone (LPZ)
In IEC standard, terms like type 1/2/3 or class 1/2/3 surge protective device is very popular. In this article, we are going to introduce a concept that is highly related to the previous terms: lightning protection zone or LPZ.
What is lightning protection zone and why does it matters?
The lightning protection zone concept is originated and described in the IEC 62305-4 standard which is an international stand for lightning protection. The LPZ concept is based on the idea of gradually reducing lightning energy to a safe level so that it won’t cause damage to terminal device.
Let’s see a basic illustration.
So what does the different lightning protection zone means?
LPZ 0A: It is a unprotected zone outside the building and it’s exposed to direct lightning strike. In LPZ 0A, there is no shielding against electromagnetic interference pulses LEMP (Lightning Electromagnetic Pulse).
LPZ 0B: Like LPZ 0A, it is also outside the building yet LPZ 0B are protected by the external lightning protection system, normally within the protection area of the lightning rod. Again, there is no shielding against LEMP too.
LPZ 1: It is the zone inside the building. At this zone, it is […]
As we know, surge protective device will degrade or even come to end of life over time due to repeated small surges, a single strong surge or sustained overvoltage. And when surge protective device fails, it may create a short circuit condition and cause safety problem in the power system. Thus proper overcurrent protection device is needed to work together with surge protective device.
There are normally two types of overcurrent protection device that used together with SPD for backup protection: circuit breaker and fuse. So, what are their Pros and Cons respectively?
- Can be repeatedly used and thus lower the maintenance cost.
- Have a greater voltage drop when experiencing surge current and thus will lower the SPD’s protection level
- Less likely to malfunction
- Lower voltage drop at surge current
- The product itself is more cost effective especially for great short circuit current situation
- After it functions, the fuse has to be replaced and thus increase maintenance cost
So in practice, both devices are used depending on the specific situation.
The Impact of Cable Length on the Protection Level of Surge Protective Device
The subject of SPD installation is rarely mentioned in our discussions. There are two reason:
- The installation of surge protective device should be conducted by an qualified electrician. We don’t want to mislead that this should be done by users. And if the SPD is incorrectly wired, it may cause hazzard.
- There are many videos on Youtube demonstrating how to install a surge protective device. It is much simple and straightforward than reading text instructions.
Yet still, we notice a very common mistake in SPD installation, even made by professional. So in this article, we are going to discuss an very important guideline in installing a surge protection device: to keep the cable as short as possible.
Why is the cable length important?
You may ask yourself this question. And we are sometimes asked by customers that why can’t you make the SPD’s cable length longer? If you make the cable length longer, then I can install the SPD a little far away from the circuit panel. Well, that’s the opposite of any SPD manufacturer want you to do.
Here we introduce a parameter: VPR (Voltage […]
SPD Application in High Altitude Areas
As an international player in surge protection filed, Prosurge has a very extensive clientele around the world. For example, we have many customers in the South America where is very famous for its plateau. Sometimes, we have customers asked us: We need to install the surge protection device in a area with altitude above 2000m, will it affect the performance of the SPD?
Well, this is a very practical question. And in this article, we are going to talk about this topic. We are going to introduce some opinions from various professionals yet kindly note that this area is still need to be explored further and thus the information we present only serve as a reference.
What’s Special about High Altitude?
The issue of surge protection / lightning protection in high altitude areas has always been a practical topic. In the ILPS 2018 (International Lightning Protection Symposium), surge protection professionals also have a discussion on this topic. So what’s special about high altitude area?
First of all, let’s look at the major climatic environment characteristics of high altitude areas:
- low temperature and radical change;
- low air pressure or […]
Whole House Surge Protection / Whole Home Surge Protection
Today, the concept of whole house surge protection or whole home surge protection is becoming more and more popular. One of the important reasons is that today there are too many electronic devices that are very expensive yet very vulnerable to power surges. It is estimated that an average house contains more than USD 15000 electronic and electrical products that are unprotected from surges. A typical surge attack may leave all the electronic and electric devices paralyzed and that’s the case you never want to experience.
So in this article, we are going to talk about this subject: whole house surge protection.
Why we need whole house surge protection?
Surge is a very common danger to home appliances. If you live in a area with frequent lightning strikes, you may already suffer from the damages it brings. Here are the stories from two victims. Does it sound similar to you?
July 2016 We experienced a power surge one week ago. Our oven (electronic board burned out). Our surround sound burned out also, as well as our Dish receiver. The transformers on the telephones, […]
We all know that it is not so easy to choose a proper surge protection device. The parameter of a surge protective device is not like the parameter of a smartphone which is obvious and easy to understand for most people. There are a lot a misunderstandings when selecting a SPD.
One of the common misunderstanding is that the bigger surge current capacity (measured in kA per phase ), the better the SPD. But first of all, let’s introduce what do we mean by surge current capacity. Surge current per phase is the maximum amount of surge current that can be shunted (through each phase of the device) without failure and is based on the IEEE standard 8×20 microsecond test waveform. For example, when we talk about a 100kA SPD or 200kA SPD. We are referring to its surge current capacity.
Surge current capacity is one of the most important parameters for a SPD. It offers a standard to comprar different surge protection device. And SPD manufacturers are required to list the surge current capacity of their SPDs. And for customer, they also understand that a SPD installed at service entrance should have a higher surge current capacity comparing the […]
Surge Protection Device Classifications
In a previous article, we introduced the one of the classification of surge protection device, that is, by type or class. Type 1/2/3 is the most common SPD classification either in UL standard or IEC standard. You can review this article via this link:
And in this article, we are going to talk more about other classifications which are not introduced at the above article.
AC SPD & DC/PV SPD
Evidently, AC SPD is much more common than DC SPD as we all live in a society in which most electrical products are powered by AC current thanks to Thomas Edison. Maybe that’s why the IEC 61643-11 standard only applicable for AC surge protective device for quite a long time there is no applicable IEC standard for DC surge protective device. DC SPD become popular as the rise of the solar power industry and people notice that PV installation is a common victim of lightning as it is normally located in open area or on rooftop. So the need of surge protection devices for PV application is growing rapidly during the past 10 years. PV sector is the most common […]
Surge Protection Device
Surge protection device (or abbreviated as SPD) is not a product that known to the public. The public do know that power quality is a big problem in our society in which more and more sensitive electronics or electrical products are been used. They know about UPS which can provide uninterrupted power supply. They know voltage stabilizer which, as its name suggest, stabilize or regulate the voltage. Yet most people, enjoying the safety that surge protection device brings, don’t even realize its existence.
We’ve been told since childhood that plug off all electrical appliance during thunderstorm otherwise the lightning current may travel inside the building and damage the electrical products.
Well, lightning is indeed very dangerous and harmful. Here is some pictures showing its destruction.
Index of this presentation
Well, this is about lightning. How does lightning related to the product surge protection device? In this article, we will give a thorough presentation on this topic. We are going to introduce:
Lightning Protection VS Surge Protection: Related yet Different
- What is surge
- What cause surge
- The effects of surge
Surge Protective Device (SPD)
- Components: GDT, MOV, […]
Surge Protective Devices (SPD) are used to protect electrical equipment against surges (overvoltages) caused by lightning or switch of heavy duty machines (many people may ignore this). It may take some technical background when selecting a proper surge protective device as there are various technologies and regulations.
The IEC 61643 standard defines 3 types of surge protective devices for low voltage electrical system.
Type 1 or Class I: Type 1 SPD can discharge strong lightning current and are installed in the main electrical switchboard when the building is protected with lightning protection system (lightning rod, down conductor and grounding).
Type 2 or Class II: These surge protective device (SPD) is designed to discharge current generated by indirect lightning hit which caused induced overvoltage on the power distribution network. Typically, they are installed at the main distribution switchboard. Type 2 SPD are the most popular SPD on the market and Prosurge is offering them with different certificates.
Type 3 or Class III: Type 3 SPDs are designed to reduce the overvoltage at the terminals of sensitive equipment and therefore has a relative limited discharge current capacity.
Where should SPD be installed?
Type 2 surge protective device will be installed in the […]