On a DC drive dynamic position drillship, we had these in our engine
controllers and underwater television systems.
Any noise spike would shut the relays off and then back on. This
caused out TV systems to shut down and restart and out power
management system to be useless. The DC drives put hash on the AC
buss which got passed back to our systems which would cause the
SSC's's to turn on/ off rapidly
Although the on/off/on pulses were less that an second, it was enough
to cause a lot of problems.
The fix?? Put mechanical relays back in, the "momentum" of the relay
kept it energized thru the hash or our AC system and the relays
stayed closed and the systems functions normally.
We have had large SSC's's for the main power to our UPS and we ripped
them out and replaced with mechanical ones.
Because SSC's's are electronic, they switch a lot fasted than
mechanical contactors and require absolutely clean power and control.
The hash TC's give out will probably cause the relays to misfire and
either damage the transformers of pop a main breaker because they
will be open/ closing a lot causing large current pulses.
Frank
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