Thread: VFD for 5hp extractor

You need to check if the motor can be configured for 220V Delta. A pic of the motor nameplate will help.
There are plenty of 5HP 240V VFDs on eBay fairly cheap.
https://www.ebay.com.au/itm/4000W-5H...sAAOSw8H1aUMRO
Just an example.

Most of the >3HP DCs motors I have looked at use Delta 415V motors which cannot be converted to run on 240V 3Phase so you might need to replace the motor.

A 5hp machine is a 5Hp machine.
SO .... how much 240V supply do you have.
Yeh you might reduce the demand, by using a VFD to reduce the speed ...... but how far do you need to reduce the speed to get within your current available and will the motor tolerate that .... AND at that speed will the blower be efficient and will it pull enough air speed.

cheers

I've attached a pic of the motor name plate if that helps. It can be on its own 15A circuit it that means anything at all.

IMG_20180606_170617076_LL.jpg

...

Originally Posted by soundman

Yeh that is its own 15 amp 3 phase circuit .. 45 amps total ....... ya got a spare 45 amps single phase.

It doesn't work like that.
To determine total current for a 3Phase device the current through any one phase current is not multiplied by 3 but the Square root of 3.

415V x 6.7A (motor nameplate current) X 1.73 = 4.8kW input power.
At 240V this translates to a total of ~20A (a long way from 45A) which is perfectly normal for a 5HP motor.

The real current draw will depend on the actual load.
If only 6" ducting connected to a machine is used it won't draw anywhere near 20A you 'd have to be using a wide open 8 or 9" ducting for it to do that.

A 3HP connected to 6" ducting typically draws about 9A total current. as does a 4HP motor, and a 5HP will not draw much more.

For safety sake it should be connected to a 20A circuit. Your 15A circuit cable may already be rated to 20A and you might be able to just change the breaker.

You could limit the total current to 15A using a VFD but it probably means you won't be able to speed it up too much.

The motor name plate doesn't say what the connection is.
Open up the motor connection box and take a photo - there might be a clue in there.

I found some other Seing motors with dual voltage on the plate so I think this one won't be a straight connection job.

Originally Posted by BobL

The real current draw will depend on the actual load.
If only 6" ducting connected to a machine is used it won't draw anywhere near 20A you 'd have to be using a wide open 8 or 9" ducting for it to do that.

A 3HP connected to 6" ducting typically draws about 9A total current. as does a 4HP motor, and a 5HP will not draw much more.

For safety sake it should be connected to a 20A circuit. Your 15A circuit cable may already be rated to 20A and you might be able to just change the breaker.

You could limit the total current to 15A using a VFD but it probably means you won't be able to speed it up too much.

The motor name plate doesn't say what the connection is.
Open up the motor connection box and take a photo - there might be a clue in there.

Thanks Bob

I'll be using 6" ducting.

My breaker panel is located in the wall connecting the house to the garage. Its on the inside of the garage, which is where the tools are. My power runs are designed to run entirely around the inside walls of the garage. What this means is that i can get a sparkie to quite easily put a new breaker/circuit in, to whatever specs are feasible. It can be specifically for the dust collector/VFD. With this in mind, would i have any options to improve performance using a VFD (i.e. beyond a 20A circuit)? I've attached a picture of the breaker panel, just in case it helps.

In a previous post you mentioned that i might need a replacement motor. Do you think this is still the case?

Also apologies if none of this makes sense. I'm a novice with electrical. Just trying to get the basics down so i know what i need/want.

IMG_20180606_221033779.jpg

Originally Posted by BobL

The motor name plate doesn't say what the connection is.
Open up the motor connection box and take a photo - there might be a clue in there.

Sorry, just saw this part. Ill take a look.

Originally Posted by skullmonkee

Thanks Bob

I'll be using 6" ducting.

this will constrain the DC nicely - but you will need to be very careful not to run it without any ducting attached on a 15A circuit. Also ask yourself what happens if the ducting falls off the front of the impeller.

My breaker panel is located in the wall connecting the house to the garage. Its on the inside of the garage, which is where the tools are. My power runs are designed to run entirely around the inside walls of the garage. What this means is that i can get a sparkie to quite easily put a new breaker/circuit in, to whatever specs are feasible. It can be specifically for the dust collector/VFD. With this in mind, would i have any options to improve performance using a VFD (i.e. beyond a 20A circuit)? I've attached a picture of the breaker panel, just in case it helps.

I can't tell much from the breaker box labels they seem to duplicate each other. I can see a bunch of ACs and spas there - you sure have a power hungry house.
You need to seek qualified advice here - I don't want to be the cause of you burning your shed down.
I'll tell you what I have experienced but someone qualified like NCArcher is better placed to be specific.
My experience is that you could get away with a 15A circuit by placing a current limit on the VFD to make sure it never goes above 15A and just accept whatever Speed that can get to at that current eg it might be something like 58Hz. This is a bit speculative you'd have to do some testing but given your experience its best left to a sparky.

In a previous post you mentioned that i might need a replacement motor. Do you think this is still the case?

We can't tell yet. Can you take photo of the inside of the motor connection box.

this will constrain the DC nicely - but you will need to be very careful not to run it without any ducting attached on a 15A circuit. Also ask yourself what happens if the ducting falls off the front of the impeller.

Thanks for this info. Basically means i will ensure the ducting is attached secure and basically permanant without removing screws etc. So i understand clearly are you saying without the ducting the unit will draw too much current?

I can't tell much from the breaker box labels they seem to duplicate each other. I can see a bunch of ACs and spas there - you sure have a power hungry house.
You need to seek qualified advice here - I don't want to be the cause of you burning your shed down.
I'll tell you what I have experienced but someone qualified like NCArcher is better placed to be specific.

Breaker box is poorly labelled by the previous owner. Something i intend to fix. For the record i will absolutely seek pro advise from a qualified sparkie. At the moment i'm just getting the basics for what i need to request. My main intention with this thread was to see if i could feasibly use the 5hp unit i have.

My experience is that you could get away with a 15A circuit by placing a current limit on the VFD to make sure it never goes above 15A and just accept whatever Speed that can get to at that current eg it might be something like 58Hz. This is a bit speculative you'd have to do some testing but given your experience its best left to a sparky.

Does this mean that if a sparkie was to put in a circuit which could support a higher current it would improve performance?

Finally, i've attached a photo of the motor connection box (i think...)

IMG_20180606_224110292.jpg

Originally Posted by skullmonkee

Thanks for this info. Basically means i will ensure the ducting is attached secure and basically permanant without removing screws etc. So i understand clearly are you saying without the ducting the unit will draw too much current?

Correct but I would not rely on the ducting size to be the controller of current

Legally as it is now it should installed on the correct circuit designed for the machine. Currently its a 3Phase 415V machine.
If it is possible to modify it and it is modified by a qualified person to run on 240V 3Phase then it could be run with a 240V VFD on a 20A circuit and the VFD programmed not to exceed the name plate equivalent current of the motor.

Breaker box is poorly labelled by the previous owner. Something i intend to fix. For the record i will absolutely seek pro advise from a qualified sparkie. At the moment i'm just getting the basics for what i need to request. My main intention with this thread was to see if i could feasibly use the 5hp unit i have.

Sure , we're worrying too much about other things - if the motor is a 415V ∆ then the priority will be to sort a new motor first.

Does this mean that if a sparkie was to put in a circuit which could support a higher current it would improve performance?

Provided you can connect it to a VFD then you could run it faster and it would draw more current - but without testing how much current it draws at various speed we won't know. This testing should be undertaken by a qualified person.

Finally, i've attached a photo of the motor connection box (i think...)
IMG_20180606_224110292.jpg

Unfortunately that doesn't tell us anything either - it could still be either Y or ∆ connected.
The only way is to now open up the motor.

Basically after opening the motor the task would be to look for definite junctions - these will be covered with some form of insulation.
Trace back the wires from the junction box if they are each connected to two other wires then its a ∆.
If they connect to one wire, and there is one 3 wire junction that does not connect to any of the wires from the junction box then its a Y.
At this point it's really a sparky or motor rewinder job.

Be careful and stay safe.

Looking at your switchboard pic - your main switch is 63A. With 3 x 32A circuits for spa, hot plates & air con along with electric oven and HWS I would say you are already over the maximum demand allowed from your mains.

Originally Posted by maxxsinner

Looking at your switchboard pic - your main switch is 63A. With 3 x 32A circuits for spa, hot plates & air con along with electric oven and HWS I would say you are already over the maximum demand allowed from your mains.

It's pretty common to do this as one assumes that not everything goes on at the same time.
We have a 63A supply, 5ACs on individual 20A breakers, A 32A induction hot plate, 32 breaker to the shed, 3 x 16A GPO circuits and a 10A lighting circuit all installed by a qualified sparkies. We're hoping to get 3Phase when underground power arrives in the near future.