3 Phase AC Motor Speed Control

Thread Starter

rups22

Joined Oct 26, 2022
6
Hi folks

I'm currently building a restaurant and commercial kitchen. The extraction system uses a fan with a 3 phase motor. I've measured the voltage at around 110/120v per phase and my clamp meter shows a draw of around 1.5 amps per phase under full load. I'm looking to build/buy a speed controller but cannot seem to find many (affordable) options. I understand I can either adjust frequency or voltage. Hoping someone can push me in the right direction of what I should be looking for. Thanks in advance
 

MaxHeadRoom

Joined Jul 18, 2013
26,278
Do you have any info off the motor? 120vac is unusual for it to be a normal 3ph induction motor.
Is this measuring 120v phase to phase?
There is 3ph 120v VFD's if you can find one.
 

LowQCab

Joined Nov 6, 2012
2,644
Be careful with what You alter in a Commercial-Kitchen,
the Fire-Marshall may Shut-You-Down for any un-approved modifications.

Exhaust-Hoods have a specific "approved" design that works as a "Balanced-System".
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Thread Starter

rups22

Joined Oct 26, 2022
6
Be careful with what You alter in a Commercial-Kitchen,
the Fire-Marshall may Shut-You-Down for any un-approved modifications.

Exhaust-Hoods have a specific "approved" design that works as a "Balanced-System".
.
.
.
Appreciate the advice. In Spain the rules are very relaxed. Regardless, the extraction fan is almost unnecessary, it's connected to a pizza oven that are typically installed without extraction fans as the hot gasses naturally rise up the ducting. I would just like to lower the RPM slightly to reduce noise.
I've tried my best to get photos of the technical data plate, it is buried deep inside the ducting on the opposite side of the motor and using my phone I have managed to get some photos but it's very hard to read. I've emailed the manufacturer asking for specifications as well.
 

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Thread Starter

rups22

Joined Oct 26, 2022
6
Do you have any info off the motor? 120vac is unusual for it to be a normal 3ph induction motor.
Is this measuring 120v phase to phase?
There is 3ph 120v VFD's if you can find one.
I was measuring with my meter from one phase to earth - this gave me 130v (all 3 measure 130v)

I received an under voltage code on the VFD that I purchased so I just assumed this was correct.
https://www.amazon.es/gp/product/B012AU2QJU/ref=ppx_yo_dt_b_asin_title_o01_s00?ie=UTF8&psc=1

I've now measured phase to phase like you suggested and it's giving me 230v

Any thoughts?
 

MaxHeadRoom

Joined Jul 18, 2013
26,278
Can you see exactly what it says under the V (voltage) indication on the label?
It almost appears to be 460v?
If you measure 230v phase-phase then the motor and VFD should conform to this.
 

LowQCab

Joined Nov 6, 2012
2,644
Many Commercial Fans are Belt-Drive.
It may be possible to simply install a smaller Pulley on the Motor.
This may require a shorter Belt.
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strantor

Joined Oct 3, 2010
6,336
Man, you have really made a laudable attempt to provide all the pertinent information but tragically missed the mark in every instance.

The one important value from the motor nameplate (voltage) is the one value that can't be read in any of the pictures.

In order to view the Amazon link you provided, I am required to change my location to Spain. I have done this in the past and my amazon account got locked into that setting and stayed that way for weeks. All Amazon listing were in Spanish. I'm sorry but I will not click yes for you.

Screenshot_20221029-092719_Amazon Shopping.jpg

Can you please post a better picture of the nameplate and provide manufacturer & model # of the VFD?


When you are measuring 130V, is this the output of the VFD? or is it the mains?
 
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