What is going on here?

By Dale Stevens; posted December 5, 2004

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I took this picture during my recent trip to Costa Rica. It is of power distribution on the grounds of the hotel where I stayed. I have seen similar setups in Colorado, but without the pyramid shaped items on the lower cross-arm. My guess is that 3-phase is coming in on the top, going to the fuse/cut-outs in the middle, then what is going on the bottom? Thanks to Jim and Dave for the answer: This is a "primary metering" setup. The box-shaped transformers reduce the line voltage to 120V while the pyramid-shaped transformers reduce the line amperes to 5 amps - the secondaries then go down to a regular 120V 5-amp transformer-type meter (this being a much safer solution than trying to build a meter with high voltage and high current feeding right into the enclosure).

What all this does is it allows the power company to meter a large industrial complex with one meter instead of having to account for numerous meters throughout the complex.

The three boxes with a wire attached to each end are current transformers (C.T.'s) and the other two are voltage transformers (P.T.'s). It looks like one of the fuses are blown on the cut-out at the left side.

Note: The picture was taken 5 hours after a 6.2 earthquake had struck and power was only partially restored at the time.