DC or low frequency AC is an almost meaningless test, although field life is
a good data point.
The only valid bench tests for a relay in these applications are RF heating
with high current, and voltage breakdown. Some relays even run current or
voltage through the coil pole center, making a "capacitor" to the control
pins. The relay has to be opened and inspected, or measured for stray
capacitances.
Almost always the heating is in the contact bar or wire to the contact bar.
Heating there is aggravated by RF current and skin effect, so it must be
tested at radio frequencies.
Contact materials should be gold overlay and ideally have a small contact
area, otherwise they develop receiving issues more frequently. The larger
and more robust the hot switching, the less reliable the receiving becomes.
I find relays that can reliably carry 20-30 amps or more at 60Hz that heat
and fail at 4-5 amps at 10 MHz.
73 Tom
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