The NB20i has pass-through with a transfer switch. The transfer switch does have a 20ms delay which some equipment might not be able to withstand due to small internal capacitance. The easy thing to do is ask DSA if they have unexpected shutdowns when they unplug our carts from the wall in the standard US 120V models. If no issue, the 230V models should not either. It is rare that the 20ms delay causes shutdowns.