SSAC BKON tower light flasher

Tower light outages are fairly typical in this business and I have spent a fair amount of time at various tower bases poking around in the junction boxes looking for trouble. Over the years, I have replaced several old mechanical tower light flashers with these SSAC solid state units. The SSAC units are nice, in that they have a zero voltage turn on, which tends to extend the service life of incandescent bulbs.

This unit appears to have taken the brunt of a lightning strike:

SSAC BKON FS155-30T tower light flasher
SSAC BKON FS155-30T tower light flasher

I would hazard a guess that lightning struck the top part of the beacon housing where the bulb socket is located, then traveled down the AC line to this device.  Luckily, it appears the the wire insulation inside the conduit to the beacon fixture is still intact.  Sometimes, under high stress, wire insulation can fail, as it is most often rated for 600 volts maximum.  I have also seen that happen on more than one tower, especially if water has made its way into the conduit.

SSAC BKON tower light flasher
SSAC BKON tower light flasher

Side view, this was mounted on a hot AM tower, but was not the unit designed for high RF environments. Those units are denoted with an “RF” suffix. The difference between the two, the RF models have bypass capacitors installed internally.

SSAC FS155-30T destroyed by lightning
SSAC FS155-30T destroyed by lightning

Lightning path to ground, through the bottom of the case.

The PIROD PRLC-A tower lighting controller

PIROD tower company has been around for a while, thus there are likely many of these tower light controllers out in the field.  They perform a vital service in controlling and monitoring tower lights at remote transmitter sites maintaining a safe operating environment for aircraft and compliance with FCC rules.

PIROD was sold to Valmont in 2004, Valmont no longer manufactures or supports the product.  All is not lost, however, as XCEL Tower Controls does support it and parts are still available through them.

These units were fairly rugged, had good surge suppression on the incoming AC lines and are designed for easy access to service parts.

PIROD PRLCA tower light controller, WRKI Brookfield, CT
PIROD PRLCA tower light controller, WRKI Brookfield, CT

This particular controller is being installed at WRKI in Brookfield, CT.  We are adding toroid cores to the tower lighting circuits coming off of the tower because the last controller has been mostly destroyed by lightning.  It is a tall tower, on top of a tall hill, thus it gets struck by lightning many times over the course of a year.

WRKI tower, Brookfield, CT
WRKI tower, Brookfield, CT

The block diagram looks like this:

PIROD PRLCA block diagram
PIROD PRLCA block diagram

Click for higher resolution.

The basic schematic looks like this:

PRCLA tower light controller schematic
PRCLA tower light controller schematic

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The entire manual can be found here, (medium sized .pdf) courtesy of John Brickley of EXEL tower controllers.