I've been thinking of using a 3 pole (for 3 phase) changeover switch for connecting a VFD to different 3 phase motors in a workshop. This switching would be done with the VFD powered down, and then powered up and the corresponding motor switched on through the VFD's input controls. The purpose would be to use a single-phase input VFD as a 3 phase supply (when 3 phase isn't available) and power several motors (not at the same time) using only one VFD (for cost saving). Whether this is practical or saves appreciable cost is to be determined. I'd appreciate your opinion if you are able to offer any thought.
I understand using this switch for a single supply and feeding two separate pieces of plant (one at a time) but I thought if you had 2 supply's to a single load (grid & generator) then a 3 position change over is required. My understanding was this is because there is a potential, just at change, on this one of both supply's being connected at the same time? But good video.
Why do all the double pole rotary switches I've searched for have 8 terminals ? If its 2 wires in (supply ) and 4 wires out (2 for one load and 2 for another ) ? Baffled
Where abouts in the world are you. If your in the UK we run 3 phases and neutral. That's your 4. Not at all written in law but you could double up your cables and half the rating of the device to save costs. Providing your happy with the terminations. Double pole means it isolates the live and neutral at the same time. Most isolator switches are used in a commercial environment. More likely that not youd expect three phases and a neutral at this point. Apologies for the late reply. I have a 1 year old that is currently balls to the wall and doesnt sleep!
pietkaify Hi thanks for replying , am in UK I need a rotary to switch between an inverter or mains hook up in RV , so I can choose which one to supply the load (sockets ) ,the UK has neural ,live, and an earth , single phase 240v ,same with inverter although I don't think the earth is used on inverters ,just want to switch ,I've read I need DPDT switch , the output can be fixed , but needs to switch at wiper between the mains electric feed or the inverter ,with an all off in the middle
