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Novembre 2011November 2012

Surge Protection for LED Lighting

Christian MacandaCITEL Product Manager

Christian MacandaThis document could not be transmitted or used, even partially, without CITEL-2CP’s prior agreement


LED lighting surge protection The needs of surge protection

The choice of LED lighting technology is often driven by the need of long duration operation. But the LED technology faces threats due to lightning surges which could reduce drastically the life duration.

Due to its external location and its connection to wide AC network, the risk of surge on LED lighting system must be really taken in account.

2 mains risks :

Ageing of LED components Lighting efficiency decay Failure of LEDs and Power Supply Loss of the LED system


Surge Voltages due to Ligthning is the main risk of failure


All luminaires are connected to earthing systems. During near-by ligthning strike, partial impulsecurrents can reach every street lights and will risethe earth potential to huge values. Heavy surges voltage differences will occur on AC network, between active wires and Earth (Class I) or Functional Earth (Class II). Destruction of Drivers and LEDs


Indirect effects of lightningon LED lighting network

Effect of near-by ligthning strike


Analysis:Lighting LED manufacturers facing failures due to surge voltages(Germany)

36%

50%

14%

1. yes

2. no

4. no answer




Surge damages :Typical damages on Power supply.

• Destruction of the input components

• Failure of the PCB tracks

• Failure of the internal MOV

• Failure of the internal line fuse



Surge damages :Typical damages on LEDs.

• Switch off of the LEDs (reset if power supply turns off/on

• Partial Failure of the LEDs


Summary

• High sensitivity of LED systems to surges

• Extended distribution network (maximum risk)

• Compliance to standards

• Expensive maintenance cost

• Dissatisfaction of the Final Customer



CONCLUSION

The implementation of dedicated Surge Protectors (SPDs) at the entrance of the LED system (inside the fixture) is necessary to improve safety and efficiency on the long duration required for lighting equipment.



The selection of the Surge Protectors for LED lighting system could be done following existing installation guides :

• IEEE C62.41.2 (USA)

• IEC 60364 (International)

LED lighting surge protection Selection of SPD


• Following IEEE C62.41.2 (USA), 2 levels of withstand are required, depending of location C (external) :

- Low exposure : 6 kV/3 kA test - High exposure : 10 kV/10 kA test




Locations following IEEE C62.41.2


Following IEC 60364-4-443 (International) , SPD are required at the entrance of the installation if :

• Installation connected to overhead distribution linesOr

• Lightning density of the area (Ng=strike/year/km²) > 2.5

Following IEC 60364-5-534 (International) , the choosen SPD must comply IEC 61643-1 std and provides a nominal discharge current (In) > 5 kA.




Without SPD, a SMPS (Swiching Mode Power Supply) used for LED system has an impulse withstand (@ 1.2/50 µs) from 2.5 to 5 kV, depending of the technology. a Surge protection is required to withstand the standards and the real phenomena ( 10 kV).

Solutions• 1st solution : Improve the dielectric strength of the devices

• 2nd solution : Include internal surge protection components

• 3rd solution : Use a external SPD



1st solution :increase the common mode withstand of the SMPS

Problem : the LEDs are mounted on a heat sink which is connected to ground : the voltage insulation will be low…

2nd solution :Another (and common) solution to improve the surge withstand could be to include internal MOV but….

1st Problem : Compliance TestAC electrical strength test (IEC60598-1 type) must be also applied to the SMPS and are generally from 1.5 to 3 kVac therefore internal MOVs could not becompatible.Solution external SPD (which will be removed during AC strength test).



2nd Problem : MaintenanceMOVs could sacrifice itseft in case of huge surge. If MOV is included insidethe power supply, the full remplacement of SMPS is required.Solution external SPD (in case of failure, SPD remplacement only).

3rd Problem : SafetyIn case of internal MOV failure, short circuit will occur and no clearinformation will be given about the nature of the failure.Solution external SPD (equipped with disconnector, status indicator and remote signalling

device (option)).



Conclusion

Implementing external SPD is the solution.SPD connected upstream the LED device allows :

• Compliance to standards• Better safety• Easier maintenance• Eliminates the need of high voltages withstand on the wires, connectors, and LED-to-heat sink interface.


LED lighting surge protection IEC 60598-1 Standard

General Requirements and Tests for Luminaires

This Part 1 of International Standard IEC 60598 specifies general requirements for luminaires, incorporating electric light sources for operation from supply voltages up to 1 000 V. The requirements and related tests of this standard cover: classification, marking, mechanical construction and electrical construction.Attention is drawn to the fact that this Part 1 covers all aspects of safety (electrical, thermal and mechanical).


LED lighting surge protection IEC 60598-1 Standard

IEC 60598-1What about the Surge Protection in this standard ?

- Surge Protective Devices (SPD) must be in compliance withIEC 61643-1 standard (standard for low voltage SPD).

- Surge Protective Devices (SPD) are connected to earth, only for fixed luminaires.

- Surge Protective Devices (SPD) can be disconnected during the electrical strength test, but only for Class I luminaires.

Comments : for Class II luminaires, SPDs can be connected between live conductors and metal parts but they cannot be removed during the electrical strength test (and they must withstand it…)


LED lighting surge protection IEC 60598-1 Standard Electrical strength testFor Class II, the SPD is not removed during the test and must withstand 2920 Vac (4U+2000V) in common mode (Live/Ground) during 1 min.


LED lighting surge protection SPD in compliance with IEC 60598-1 Standard The SPD For Class II, the SPD is not removed during the test and must withstand 2920 Vac (4U+2000V) in common mode.

Reference Standard

In (Nominal

Discharge current)

Connection to ground point

SPD for

Class I luminaire

IEC 61643-11 > 3 kA (IEEE)

> 5 kA (IEC)

Yes

SPD for

Class II luminaire

IEC 61643-11 > 3 kA (IEEE)

> 5 kA (IEC)

No (L/N protection only)

or

Possible only if withstand to 3000 Vac test


LED lighting surge protection CITEL Range MLP

Description

Dedicated range of Surge Protective Devices (SPD) for implementation in the LED fixture.


LED lighting surge protection MLP Range from CITEL

Description

• More than 48 versions possible

• Class I and Class II insulation version

• Very compact dimensions

• IP65 version

• Combined AC/Data version (DALI or RS422)

• Wire or screw terminal output

• Max. discharge current 10 kA

• Remote status signalling (option)

• IEC 61643-1 / EN 61643-11 standard compliance

• Safe end of life (line disconnection or protection disconnection)


LED lighting surge protection MLP Range

Description :

Different applications=

Different schemes

3 main segments :•Streets, roadways•Highways•Tunnels


LED lighting surge protection Installation

In order to provide a safe operation of the LED lighting network, these points must be follow :

• SPD on AC input of each LED lighting system

• SPD on control line of each LED lighting system, if any

• SPD on general AC cabinet


LED lighting surge protection Installation



THANK YOU

Engineering

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