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I noted a huge difference between a static transformer and a mobile transformer. Static do tend to be larger so not a direct comparison however static transformer having been left on unused for a week is barely warm the mobile yellow brick is really hot. Read the info and static transformer rated at 5kVA is continuous where the mobile one is intermittent use.
Clearly you have to carry the mobile transformer so weight is rather important also size so they tend to fill with epoxy resin which both helps transmit the heat to out side of the box and also absorbs the heat so a 3kW load when on is producing more heat than it can radiate so it's stored and released latter.
The static unit is both heavier and larger often with a large space inside for the cooling air to circulate and it is common for MCB's to be fitted to both outputs and input. Often a pair of 16A sockets share one 20A MCB although not always so using just one of the pair with found large machines like vacuum cleaners with three motors which were well over the 16A rating would work OK.
With the yellow brick often the overload consists of a 12A overload which is thermal only and fitted in the incomer only so even if it trips spot on 12A then 12 x 230 / 55 = 50 amp to earth before it will trip. What it relies on is the user not using long leads so any damage to a lead will cause over 50A to flow so tripping the over load before it melts the cable. It does kind of make the whole idea silly, safer to use 230 volt but rules are rules and nothing to do with safety. So really the yellow brick is to allow one to use 110 volt equipment where there is no 110 volt supply it does not make anything safer.
So in your case a 3.3 kVA static transformer will likely trip the MCB unless you use a 32A outlet but likely would run the device. However a 3.3 kVA yellow brick will likely not trip the over load but will over heat and possibly not deliver the start current required.
For a B20 MCB to trip the loop impedance needs to be 1.1Ω line to line and 0.55Ω line to earth it is unlikely the transformer has that impedance never mind the cables between the transformer and the appliance as well. If we use the new 95% rule it is unlikely any yellow brick will ever have a low enough earth loop impedance. As the transformer size increases so the earth loop impedance (ELI) drops and this applies to both physical size and rating size. Feeding a 5kVA transformer needs around 22 amp and likely a C32 MCB would feed it. But with a 3.3kVA brick likely a B20 MCB would hold in as they are designed to work with a 13A fuse which needs an impedance of 2.42Ω compared with B20 2.30Ω so a B20 MCB should in theroy trip slightly before a 13A fuse. If we were to use a 3.3kVA fixed transformer likely it would need a C20 MCB where the required ELI drops to 1.15Ω.
Clearly you have to carry the mobile transformer so weight is rather important also size so they tend to fill with epoxy resin which both helps transmit the heat to out side of the box and also absorbs the heat so a 3kW load when on is producing more heat than it can radiate so it's stored and released latter.
The static unit is both heavier and larger often with a large space inside for the cooling air to circulate and it is common for MCB's to be fitted to both outputs and input. Often a pair of 16A sockets share one 20A MCB although not always so using just one of the pair with found large machines like vacuum cleaners with three motors which were well over the 16A rating would work OK.
With the yellow brick often the overload consists of a 12A overload which is thermal only and fitted in the incomer only so even if it trips spot on 12A then 12 x 230 / 55 = 50 amp to earth before it will trip. What it relies on is the user not using long leads so any damage to a lead will cause over 50A to flow so tripping the over load before it melts the cable. It does kind of make the whole idea silly, safer to use 230 volt but rules are rules and nothing to do with safety. So really the yellow brick is to allow one to use 110 volt equipment where there is no 110 volt supply it does not make anything safer.
So in your case a 3.3 kVA static transformer will likely trip the MCB unless you use a 32A outlet but likely would run the device. However a 3.3 kVA yellow brick will likely not trip the over load but will over heat and possibly not deliver the start current required.
For a B20 MCB to trip the loop impedance needs to be 1.1Ω line to line and 0.55Ω line to earth it is unlikely the transformer has that impedance never mind the cables between the transformer and the appliance as well. If we use the new 95% rule it is unlikely any yellow brick will ever have a low enough earth loop impedance. As the transformer size increases so the earth loop impedance (ELI) drops and this applies to both physical size and rating size. Feeding a 5kVA transformer needs around 22 amp and likely a C32 MCB would feed it. But with a 3.3kVA brick likely a B20 MCB would hold in as they are designed to work with a 13A fuse which needs an impedance of 2.42Ω compared with B20 2.30Ω so a B20 MCB should in theroy trip slightly before a 13A fuse. If we were to use a 3.3kVA fixed transformer likely it would need a C20 MCB where the required ELI drops to 1.15Ω.
