All You Need to Know About Surge Protectors

May. 21, 2019

All You Need to Know About Surge Protectors

The dysfunction of technical installations, systems and electronic equipment in commercial and residential buildings can be super annoying and unpleasant. These failures can cost you fair amount of money. Hence, flawless and faultless operation of devices and appliances must be ensured both during the normal usage and thunderstorms. The number of annually registered lightning mishaps and activities is quite huge and keeps on increasing over years. The damage statistics of insurance companies evidently show the deficient preventative and protective measures in both commercial and residential sectors.

In order to avoid such incidents that can sometimes prove fatal a professional solution is devised. This preferably allows to take significant protection measures. Of many such answers Surge Protection Devices are one. Surges that happen during a thunderstorm are due to a direct lightning stroke or remote lightning stroke. When the light strikes the resultant voltage is extremely dangerous and hazardous for the electrical devices and installation.

Surge Protection Devices

A device which diverts or limits surge current or voltage is known as Surge Protection Device. The head job of the system defending against surges is to protect electronic equipment from "surges." A surge or transient voltage is an increase in current that is significantly greater than a specified level in the current.


SPD is utilized to constrain transient over voltages of air or Switching Surge and offers way to the extreme flow to earth subsequently restrain the overvoltage to a worth that isn't dangerous for the electrical establishment.

Protection Modes

There are three protection modes available

Differential Mode (L-N)

Common Mode (L-PE)

Common Mode (N-PE)

Reasons of Surges


• External Surge:

Lighting Electromagnetic Pulse (LEMP)

• Direct lightning strike

• Indirect lightning strike caused by lightning currents

• Indirect lightning strike (reaction caused by earth connection or electromagnetic induction)

• Internal Surge: Switching Electromagnetic Pulse (SEMP): Switching on/off of inductive loads.

Tripped circuit breakers and fuses.

Short circuits.

Malfunctions caused by the power company.

Insulation Failures: Arcing Ground: Ignition and interruption to electric arc.

Switching in the grid

Earth fault or short circuit

Triggering of a fuse

Electrostatic discharge

Classification of SPDs

These security gadgets are ordered by their capacities. They are available in 10kV surge protectors, 15kV surge protectors.


• Surge Protectors for Class I Luminaires

SPD which can release fractional lightning current with an average waveform 10/350 μs. Normally utilizes flash hole innovation. This, whenever required, will be introduced in the essential dissemination 5KA led Surge protector board at the root of the electrical establishment. A Type 1 SPD does not in itself offer the required security level and should be utilized related to compose sort 2 gadgets. An establishment with a lightning assurance framework will require a Type 1 SPD. They ground the extra voltage.



• Surge Protectors for Class II Luminaires

SPD which can avoid the spread of over voltages in the electrical establishments and ensures hardware associated with it. It more often than not utilizes metal oxide varistor (MOV) innovation and is described by a 8/20 μs current wave. This gadget would typically be in sub-circulation sheets and in the essential dispersion board if there was no prerequisite for a sort 1 gadget.


•  Type 3

These SPDs have a low release limit. They should in this manner just be introduced as an enhancement to Type 2 SPD and in the region of touchy burdens. Type 3 SPD's are described by a mix of voltage waves (1.2/50 μs) and current waves (8/20 μs).

Specialized Information

The specialized information of these gadgets involve data characterizing their states of utilization as indicated by:


• Use (for example establishment, control supply conditions, temperature)

• Execution if there should be an occurrence of impedance (for example drive current release limit, pursue current dousing capacity, voltage insurance level, reaction time)

• Execution during the task (for example ostensible current, weakening, protection obstruction)

• Execution if there should be an occurrence of disappointment (for example reinforcement meld, separation gadget, safeguard, remote flagging choice).


Breaking capacity, follow current extinguishing capability Ifi

The breaking limit is the uninfluenced (imminent) r.m.s. estimation of the mains pursues current which can consequently be smothered by the surge protection gadget when interfacing UC.

Disconnecting time ta

The disconnecting time is the time passing until the automatic disconnection from power supply in case of a failure of the circuit or equipment to be protected. The disconnecting time is an application-specific value resulting from the intensity of the fault current and the characteristics of the protective device.

Energy coordination of SPDs

Energy coordination is the selective and coordinated interaction of cascaded protection elements (= SPDs) of an overall lightning and surge protection concept. This means that the total load of the lightning impulse current is split between the SPDs according to their energy carrying capability. If energy coordination is not possible, downstream SPDs are insufficiently relieved by the upstream SPDs since the upstream SPDs operate too late, insufficiently or not at all. Consequently, downstream SPDs as well as terminal equipment to be protected may be destroyed

Lightning impulse current Iimp

The lightning impulse current is a standardized impulse current curve with a 10/350 μs wave form. Its parameters (peak value, charge, specific energy) simulate the load caused by natural lightning currents. Lightning current and combined arresters must be capable of discharging such lightning impulse currents several times without being destroyed.

Maximum transmission capacity

The maximum transmission capacity defines the maximum high-frequency power which can be transmitted via a coaxial surge protective device without interfering with the protection component.

Nominal discharge current In

The nominal discharge current is the peak value of a 8/20 μs impulse current for which the surge protective device is rated in a certain test program and which the surge protective device can discharge several times.

Nominal Load Current (nominal current) IL

The nominal load current is the maximum permissible operating current which may permanently flow through the corresponding terminals.

Nominal voltage UN

The nominal voltage stands for the nominal voltage of the system to be protected. The value of the nominal voltage often serves as type designation for surge protective devices for information technology systems. It is indicated as an r.m.s. value for AC systems.

Protective circuit

Protective circuits are multi-stage, cascaded protective devices. The individual protection stages may consist of spark gaps, varistors, semiconductor elements and gas discharge tubes (see energy coordination).

Remote signaling contact

A remote signaling contact allows easy remote monitoring and indication of the operating state of the device. It features a three-pole terminal in the form of a floating changeover contact. This contact can be used as break and / or make contact and can thus be easily integrated in the building control system, controller of the switchgear cabinet, etc.

Response time tA

Response times mainly characterize the response performance of individual protection elements used in arresters. Depending on the rate of rise du/dt of the impulse voltage or di/dt of the impulse current, the response times may vary within certain limits.

Return loss

In high-frequency applications, the return loss refers to how many parts of the “leading“wave are reflected at the protective device (surge point). This is a direct measure of how well a protective device is attuned to the characteristic impedance of the system.

Total discharge current Itotal

Current which flows through the PE, PEN or earth connection of a multipole SPD during the total discharge current test. This test is used to determine the total load if current simultaneously flows through several protective paths of a multipole SPD. This parameter is decisive for the total discharge capacity which is reliably handled by the sum of the individual paths of an SPD.

Voltage protection level UP

The voltage protection level of a surge protective device is the maximum instantaneous value of the voltage at the terminals of a surge protective device, determined from the standardized individual tests:

•  Lightning impulse spark over voltage 1,2/50 μs (100%)

•  Spark over voltage with a rate of rise of 1 kV/μs

•  Measured limit voltage at a nominal discharge current In

The voltage protection level characterizes the capability of a surge protective device to limit surges to a residual level.

Wave breaker function

Due to the technical design of type 1 SPDs, energy coordination of SPDs considerably varies. Experience has shown that even small amplitudes of the 10/350 μs lightning impulse current overload downstream SPDs or even destroy them if varistor-based type 1 lightning current arresters are used. In case of spark-gap-based type 1 arresters, in contrast, virtually the total current flows through the type 1 arrester. Similar to a wave breaker the energy is reduced to an acceptable level. The advantage is that the time to half value of the 10/350 μs impulse current is reduced due to the reduction of the impulse time and the switching behavior of type 1 SPDs. This considerably relieves downstream SPDs

Thermal disconnector

Surge protective devices for use in power supply systems equipped with voltage-controlled resistors (varistors) mostly feature an integrated thermal disconnector that disconnects the surge protective device in case of overload and indicates this operating state. The disconnector responds to the “current heat” generated by an overloaded varistor and disconnects the surge protective device if a certain temperature is exceeded. The disconnector is designed to disconnect the overloaded surge protective device in time to prevent a fire.


They cover vast areas of applications and find many uses in medical field, military and industry. But they are specifically used to protect the LED luminaires and LED drivers. They are employed at street lightings, traffic lightings and signages. They are mainly used to protect the outdoor lighting systems.

Standards for Safety

GB- 18802.1 certified products

IEC- 61643. 11 Internationally recognized devices.

UL 1449 Third Edition is a set of safety standards for surge protective devices (SPDs).

 UL 1449 Second Edition standards apply to devices that are designed to limit repeated transient voltage surges.


Most SPDs have a sign window that they are operational. On the off chance that the pointer is green they are giving assurance. But if they happen to be red, at that point they have come to 'end of life' and will need supplanting. Frequently there is a replaceable cartridge which can just be pulled back and supplanted with another operational gadget.

 How do Surge Protection Devices Work?

A standard surge protector defends the electric current from the output to several electrical and electronic devices connected to the power strip. If the voltage of the outlet increases or increases (above the accepted level), the overvoltage shield diverts additional electricity to the grounding link of the outlet.

In the most common type of defending against surges, a component called metal oxide varistor, or MOV, deflects the additional voltage. An MOV forms a connection between the high voltage line and the ground line. An MOV has three parts: a piece of metal oxide material in the middle, connected to the power line and grounded by two semiconductors.

These semiconductors have a variable resistance that depends on the voltage. When the voltage is below a certain level, the electrons in the semiconductors flow in such a way that they create a very high resistance. When the voltage exceeds that level, electrons behave differently, creating a much lower resistance. When the voltage is correct, a MOV does nothing. When the voltage is too high, a MOV can conduct a lot of current to eliminate the additional voltage. When the additional current is diverted to the MOV and to the ground, the voltage in the hot line returns to a typical level, so the resistance of the MOV trips again. In this way, the MOV only deflects the overvoltage current, while allowing the standard current to continue feeding any machine that is connected when defending from overvoltage.

Why do one use Surge Protection Devices?

Open-air lights are vulnerable to transient spikes by lightning strikes that are inductively coupled onto electrical cables. Surges can be brought about by direct lightning, aberrant lightning or turning OFF/ON of mains supply.

Other than surges, if HV line contacts LV line or if the neutral association is frail or gliding the stage Neutral voltages can go higher than recommended cutoff points of a luminaire. These surge voltage can annihilate LED power supplies just as the LED's themselves. Because of the delicate buildup of LED lights, we have to give over-voltage, over current, surge security for LED lighting frameworks, the most widely recognized sort of surge defender contains a segment called a metal oxide varistor or MOV, which occupies the additional voltage and vitality away from the gadget it is ensuring. On account of LED Lights, it will ensure LED Driver or LED itself.

QIYU tech gives SPD modules which will give security in abundance of 10kV, 15kV and 20kV. This security is there between Phase-Neutral, Neutral-Earth, and Phase-Earth. We offer these modules inbuilt inside the open-air luminaires, for example, road lights, floodlights and so on.

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