Hi I have a problem with a 3 phase industrial ironer. main components are (3) inverters roughly 8 amps per phase (24 amps) no further details at this time.the circuit is protected with a C50 Amp MCB feeding a 300mA type B RCD. The RCD has tripped, and now will not reset even with the load disconnected and therefore requires replacement. The ironer is new. what are your thoughts?