Apologies to Steve, as it is not strictly towers or antennas, but may have
implications if someone is using a portable power generator on a tower
project. Chuck and Rick and others, you may have opinions.
On our recent Dxpedition to OC-251, VI3JPI, I took along my new Honda E20i
generator as our principal power supply. When we connected up Earth Leakage
Detectors to the outlets, the ELDs continuously tripped. On return from the
Dxpedition I contacted Honda (Australia) to find out why. Apparently the
way the inverter is earthed, means that there is a residual current always
in the earth lead, which trips the ELDs. In Australia, where ELDs are now
mandated, they have had to get an exemption from the various State
Electricity Authorities.
Anyway, on the Expedition, we initially had a deal of line noise feeding
back to the rigs and being picked up by the antennas. There was an earth
stake right next to the generator. Fortunately, I had brought along a
number of clip on ferrites with half inch internal diameters that could be
clipped on the power cords at the generator, making a big difference. The
specs on the ferrites was: 1mhz = 10ohms, 25mhz = 150ohms, 100mhz = 250
ohms, 300mhz = 290 ohms.
For our next IOTA expedition at Easter, we were planning to make up some
sort of filter box with ferrite toroids in a common mode configuration,
which could be plugged in to the generator output like a very small
extension lead.
Having read the discussion about DC currents and their effect on
magnetising, might there be a better way to configure the toroids than
before? In discussion with Honda, the engineeer did say that a number of
similar generators, configured as solid state inverters, had the same
problem with ELDs.
We were even thinking of using ferrites rods, with both active and neutral
would in a bifilar fashion, but now we are not so sure.
Any comments or advice would be appreciated.
Cheers
Peter VK3QI
|