Topband: Vacuum relay powering #2

[Dr. Wolff Ostwald]

Hi reflectees ! 
I guess the relay issue is of common interest here.
Even if a surface seems to be hard and rigid, the common contact surface can be enhanced by extra pressure, with an accurate Ohm-meter You can measure that. At a relay contact regularly there is dissipated heat, pressure leads to a more common heat conducting body of metal and minimzes thermal differences and surface bending by heating. Everybody who contacted wires with sufficient current with bare fingers knows the effect of pressure at metal to metal contacts. The relay manufacturer knows why he says 26.5 Volts, he knows the magnetic force necessary to make a contact pressure to yield the current allowance and specifications.
At the cost of vacuum relays it may not be a good idea to save a penny per year electricity for the coil and loose a 100 dollar+ relay.
73 de wolf  df2py