Hi All, With some trepidation I am throwing this one out for comments / advice from members.
I have been asked by a customer to provide 3 phase supplies for some 'machines' that are under development by my customer.
The machines are basically cabinets for dehydrating food items , that have been designed by my customer as he has been unable to find a suitable commercial product that will meet his needs.
So far he has arrived at a test machine that has a fabricated upright steel cabinet with heating elements mounted at the rear and multiple fans at the front, drawing warm air over the food which is spread over trays stacked on a shelved trolley that is wheeled into the cabinet.
There are 3 x 3kW single phase heaters that are separately controlled by solid state relays and the fans are ELV units that are electronically controlled by a series of thermostatic probes, the idea being to maintain the correct temperature, humidity etc over the height of the unit so that the food dries evenly.
At present he has everything supplied via multiple 13A plugs connected to various sockets which may or may not be on the same circuit / phase. I have cautioned him on overloading circuits etc.
His prototype is now working (pic) and he wants to turn this into a finished appliance that will be used commercially and copied for use in his own premises.
Whilst he is taking full resposibility for the appliances themselves (compliance with relevant regs etc) I have been asked to install supplies and assist with packaging the electrical elements of the design.
I can see no problem with supplying the unit from a 5-pin 16A RCD socket as the heater elements although separately controlled will be roughly in balance (similar load) and the ELV parts will be a negligible (single phase) load in comparism.
My thoughts on packaging are that the different voltages present should be separated adequately (different enclosures,double insulation, sheathing etc) and that the steel casing should be of course adequately earthed.
Also I have thought that a 'fail safe' thermal trip operating an 'upfront' contactor might be advisable.
Any other thoughts? other than run a mile, which is kind of what I am expecting...
View attachment 43830