As ever I am relying on the combined wit and wisdom of this forum to evaluate a problem.

I am peripherally involved in a project trying to improve the processing of various agricultural projects in West Africa. part of the work involves setting up various experimental dryers in rural areas to improve the lifespan of things like tomatoes, chilli, fruits etc etc by drying them.

Local firms have built two kinds of dryer – one is essentially a charcoal oven with a fan attached to blow the hot air through a sealed space to dry the produce in a controlled way. The other, based on the pictures I have just received, looks like a pile of old fashioned electric stove elements stacked up, fully exposed, to generate the heat for drying. Not the greatest regard for health and safety or practicality. Can't see any direct control for the elements but maybe there is a thermostat elsewhere.

I have asked repeatedly for more information but none is forthcoming. The local fabricators have knocked this together so no design manual, plans or design briefs whatsoever.

The problem?? Apparently the motors blowing the hot air from the charcoal burner AND the heating elements are set up to require a 3 phase supply. The local village only has access to single phase from Nigeria's erratic grid and/or a generator.

As a consequence these dryers are useless unless a workaround can be found either by reconfiguring the wiring or adding some technical gizmos better understood by the electrically minded – and that isn't me.

Presumably the motors should be a relatively easy problem to solve – either replace with single phase or add a phase converter. No idea of power etc of the motors so please don't ask. Common sense suggests under 1HP but maybe you can assess them from the picture?

The array of heater elements is presumably more complex. I doubt the single phase supply will deliver more than 20A at 240V 50Hz (grid will fluctuate between 210-240 and between 50Hz and 60Hz in my experience).

This is the only feedback from an administrator sent to the village to get more details " Based on my request for the power of each element I was told the elements are 18kw. There are about 5 elements. However the total rating of the equipment was meant to be 20kw based on the spec given for the dryer so maybe each element is 4kw. The fan was said to to be 4kw. There are two fans."

I haven't seen the kit so maybe the heating elements are actually the size of dustbin lids by experience suggests someone has simply repurposed some cooker elements???

So dear forum. We have some cooker elements potentially wired up to draw on a 3 phase supply (I don't really know what these words mean) and 3 phase motors. Can these two separate 'inventions' be re-wired to work and run off a singly phase, 240V supply bearing in mind the potential current drain.

If they can't there is a need to create a stand alone 3 phase supply to the village. Which probably won't happen.

Some pictures which may or may not help. Please don't attempt this at home . . .

Edited By Andrew Smith 16 on 13/05/2022 10:04:27

Thanks both. That confirms my worst fears.

Someone will need to stump up for 3 phase supply.

On another tack I'd be interested to know if it would be possible to develop something similar using single phase by reconfiguring the design in some way. Power consumption is always going to be a big factor in cost effectiveness and general usability given the erratic supply and fuel prices of running of a generator.

I recommended a system that was little more than a black box with a solar powered fan wafting air over the produce.

And believe me, that wiring setup is absolutely state of the art on these parts.

Many thanks again. I will break the bad news.

Andrew