VFD (or maybe Speed Controller) conundrum...

[GRW]

Guy I'm working for has some Biomass Boilers fuelled by Firewood Furnaces.
Now first off know nothing much about them & haven't seen the complete things in service - but today he waved some old parts at me and basically told me....

There is a fan motor at the rear of the burner unit. This has what I'm told is a Single Phase IN & Single Phase OUT, Variable Frequency Driven Motor.
The VFD piggy-backs off the motor casing.
In turn the Furnaces unit has a main controller, which I'm told interacts & signals the VFD to alter speed ( for example if the furnace door is opened the fan speed automatically goes to max, the only time I'm told it does so).

Here's the thing.... the VFD's are fragile & go pop a lot, znd the OEM supplied replacements are £500 each . Consequently another solution is being sought.
Questions:
1. Are 1ph - 1ph 230vac to 230vac VFD readily available affordably?
2. If no to 1 above, could a 1ph motor speed controller be used instead?

(Note owner is happy to have a manual speed control knob and dispense with the main controller issuing what I assume is an automated signal version of a manual potentiometer. The OE VFD has connections for 1ph+N+E in and out, plus a 3-pin connector which I think must be for the signal from the main controller to change speed - see pics).

Motor: 1ph 250 watt rated

VFD gubbins (note 3 pin connector bottom right on PCB, while on left top us power out, and power in is left bottom:

Sorry its so bit vague, but that's all I've got to go on atm!

TIA, G.

 

[waddycall]

I would be wary of doing anything other than fitting standard parts to it. There may be some other safety features in there that could possibly end up being overridden.

 

[GRW]

I would be wary of doing anything other than fitting standard parts to it. There may be some other safety features in there that could possibly end up being overridden.

That thought occurred to me immediately too.
However "not my circus, not my monkey" as it were.
Owner has decided (& knows how the kit works while I dont) on this "solution" - all I've been asked is to look into the theoretical feasibility of making something work, and with what pieces of kit.
(I didn't even bother getting into the discussion, as I know he's one of those types who'd not be deflected by any rationale. Luckily, I know the siting & location of said boilers.... & if any mods burnt the lot to the ground, it's all nowhere near anyone else or their property - so he'd be the only loser).

 

[eddie49]

Yes, 1-phase in-and-out VFDs are available. E.g.:

RS PRO Inverter Drive, 0.75 kW, 1 Phase, 200 → 240 V ac, 11 A | RS

uk.rs-online.com

I assume there are some power semiconductors under the PCB, mounted on a heatsink?
I would suggest you ask the owner to give you a few defective units, and then check if it is always the same component that fails when they go pop. It may then be possible to replace that part with a similar but higher-spec version.

 

[GRW]

Yes, 1-phase in-and-out VFDs are available. E.g.:

RS PRO Inverter Drive, 0.75 kW, 1 Phase, 200 → 240 V ac, 11 A | RS

uk.rs-online.com

I assume there are some power semiconductors under the PCB, mounted on a heatsink?
I would suggest you ask the owner to give you a few defective units, and then check if it is always the same component that fails when they go pop. It may then be possible to replace that part with a similar but higher-spec version.

Thanks @eddie49 for that info!
There is a massive heatsink yes, so you could well be right. I'm no electronics dude though, so confess I've never considered how to test a semi-conductor (resistance measurement??)

But it's a good idea - if it's a common component failing that could be replaced, that'd butter a lot of parsnips!

(The siting of the motor & VFD is on the back of the firebox, and between that and the flue - so I'd not be in the least surprised that excessive heat has accelerated the demise of something. Poor design IMO. It'd only take extending a few wires to re-position the VFD somewhere much cooler - so this is something else on the cards in the quest for reliability)

 

[Seadog]

VFD Board 0.55 KW 1PH 230V 50/60Hz Mobicool

This VFD board is for 0.55 KW motors, operating at 1 phase, 230V, 50/60Hz, intended for Mobicool systems, ensuring precise control and energy efficiency

www.misting-systems.com

 

[GRW]

VFD Board 0.55 KW 1PH 230V 50/60Hz Mobicool

This VFD board is for 0.55 KW motors, operating at 1 phase, 230V, 50/60Hz, intended for Mobicool systems, ensuring precise control and energy efficiency

www.misting-systems.com

That looks identical to the OE unit (I think the boilers are Italian made, & doubt very much that the VFD is specific to their boiler)

 

[eddie49]

That board looks like an exact match for the original, and about half the quoted £500 price.

 

[GRW]

That board looks like an exact match for the original, and about half the quoted £500 price.

Same old story. And OEM uses bought in components, removes all branding, then doubles the price for the part

 

[Seadog]

That looks identical to the OE unit (I think the boilers are Italian made, & doubt very much that the VFD is specific to their boiler)

Which is why I posted the link.

 

[GRW]

Which is why I posted the link.

Much appreciated - well found

 

[Seadog]

Google Lens sometimes comes up trumps.

 

[GRW]

Google Lens sometimes comes up trumps.

Sounding Fick here - but Google Lens is a new one on me!

 

[Turbo]

Another alternative would be a single to 3 phase vfd and fit a 3 phase blower motor. You would need to find out how the boiler ramps up the speed to see it that will work with a different vfd.

Whatever way you do it you should do as you suggest, ie remote mount the vfd away from the heat and vibration. Both will shorten the life of a vfd significantly.

 

[prepman]

Yes, 1-phase in-and-out VFDs are available. E.g.:

RS PRO Inverter Drive, 0.75 kW, 1 Phase, 200 → 240 V ac, 11 A | RS

uk.rs-online.com

I assume there are some power semiconductors under the PCB, mounted on a heatsink?
I would suggest you ask the owner to give you a few defective units, and then check if it is always the same component that fails when they go pop. It may then be possible to replace that part with a similar but higher-spec version.

Electrolytic caps usually.