Surge Protection for LED Street Lights

Oct 20, 2018 12:11:00 AM

Surge Protection for LED Street Lights

New LED Street Lights are being installed in street and highways and replacement of conventional luminaries is also in progress because LEDs consumes less power and offer a good lifespan. Outdoor public installations are more exposed to the environment and are located where continuous service is essential. Although there are many advantages of LED lights but one major drawback of LEDs is that their repairing and replacement cost of components is relatively higher than that of conventional luminaries and LEDs gets easily affected by surges. To avoid unnecessary maintenance and long life, you must install Surge Protection for LED Street Lights.

LED Street Lights are affected by surges due to below major causes:

  1. Lightning strike, direct lightning strike to LED street light. Very long distance outdoor power distribution lines are susceptible to lightning strikes and a large current can be conducted through power lines due to lightning, cause damage to street lights.
  2. Indirect lightning strike causes interference in the supply line.
  3. High voltage surges from a power line, from switching operations, earth problems etc.

Voltage Surge is a very High Voltage Spike mainly of several Kilo-Volts, for a very small interval of time, a few microseconds. That’s why you need Surge Protection for LED Street Lights.

Voltage Surge

Many LED lighting manufacturers and suppliers notice that once LED street lights are struck by a surge, different components i.e. power supply, LED chips even sometimes full module got damage and must be replaced and the process of uninstalling the luminaire from the pole is a very difficult procedure. Although experts in lighting industry research a lot for this problem and developed some drivers with higher dielectric strength; but these drivers are very expensive and there is still a fair chance of damage in case of a surge. Again this explains the importance of surge protection for led street lights.

Investing a small amount in protection can extend the lifetime of Street Lights and reduce the overall cost of operations and infrastructure

Now the question arises is, how can we provide Surge Protection for LED Street Lights? This can be done by installing protective devices called surge arrestors on the main line and connecting it in series or parallel configuration. When connected in parallel, LED light will still work if the surge protection device is damaged because of the parallel connection.

Surge protection device (SPD) will act as a voltage controlled switch which will remain passive till system voltage is lower than its activation voltage. When the system (input voltage in case of LED street lights) increases SPDs activation voltage, SPD will divert the surge energy protecting the luminaire. Lightning is very important when installing SPDs, choose a device which can withstand maximum impulse voltage.

Installation of Surge Protection for LED Street Lights:

Below figure show places where surge protection devices can be installed on the LED street light:

  1. Directly into the street light, installed inside driver cabinet.
  2. Installed inside the distribution board.

Surge Protection for LED Street Lights

The distance between the luminaire and surge protection device must be kept minimum to ensure proper protection, it should be kept as short as possible. If the distance between the light and distribution board is more than 20 meters, use of secondary protection device is recommended in the majority of cases.

IEC Standards for Surge Protection: According to IEC61547, all outdoor lighting products must be protected from surges up to 2kV in common mode.  But surge protection up to 4kV is recommended. Out of the causes mentioned in International Protection standards, the cause which affects most outdoor street lights is a direct lightning strike on distribution lines (surge conducted through power lines). Installation area must be properly checked and accessed for the possibility of lightning strikes and the chances of a lightning strike are higher, protection of 10kV is recommended.