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Help! Blower motor control
In what now seems like a slightly hasty decision I purchased a hand dryer motor and controller for my roaster. It?s an Exel Xlerator, the type that make your hands look like they?re made of putty when drying them. Anyway, on paper it?s just what I need with regards to CFM and static pressure, the only thing is....

1. It stops every thirty seconds
2. There?s an IR sensor that needs to see movement otherwise it locks out the unit thinking there?s an obstruction.

The motor runs three phases (metering shows each to be DC and about 300V) and has some sort of speed sensor circuitry

The control unit does all of the rectifying via kbj2506 and has a dsPIC30F2010 programmable chip to control everything.

I know many of you are far smarter than I?ll ever be so I?m reaching out to see if any of you help me reprogram the chip or point me in the direction of a dummies guide to remove the 30 second timer and IR sensor?

Otherwise, is there a simpler solution for controlling the motor?

Edited by ACEMBL on 03/19/2021 6:47 AM
Do you want it just fixed, i.e. run at a fixed speed, or want also speed control ?

How is the three phases connection: star or delta ?
Basically, you should connect the windings as one of the scenarios in the attached picture.
renatoa attached the following image:
Hi Renatoa, Thanks for the diagrams. I?ve been using a single phase side channel blower for a while but really wanted the variable speed so I can tune the throw of the beans for different varieties and as they warm up.

How would I identify how the phases are connected? There are three main wires going to the motor windings and five to the sensor on the top.
The usual UVW and they connect back to a chipset that controls the power and switching.

I?d add a picture but I don?t seem to have an option at the moment.
For a variable speed three phase motor you could look at various VFD open source projects:


There are cheap variable speed boxes on ebay, like these:
...but no idea if they match your motor and sensor
Thank you for the info, I can instantly see now what on this board does what. I wasn?t far out in my guesstimation. I?ll persevere with the reprogramming route first and if that fails see if I can repurpose many of the components from the board and control it via Arduino.
Good evening all,

I’m revisiting an old project and looking to build a new one too. The first is a 500gm (1lb) and the second is a 280gm (1/2lb) roaster. Both are of a Sivitz/Neuhaus inspired design.

I built it during the first UK lockdown with the few bits I could obtain. It uses a 3.3KW heat gun element mounted on a side channel blower for propulsion. It’s ok but rather too restrictive (limiting roasting to 300gm) so am looking at improving on the airflow. I have seen positive mention of porcupine elements. Is this still considered a worthy option, if not what would you recommend?

If yes to above… From a little research I’ve done so far there seem to be a few alloys available for the elements. Is there a particular alloy best suited to this type of application?

The current blower for the larger machine is 1.4m3/min max and static pressure of 130mbar. How would I best calculate the element requirements. Would the current element stand as a good guide?

I’ve been experimenting with a bit of heat recycling as in the cold weather I have struggled to get the temperature up sufficiently fast for the profile. It’s been pretty successful so am looking at developing it on a bit. The side channel blower seems good for about 70~80C inlet temperature and cuts energy requirements by about 25/30%. I’m going to look for a suitable splitter valve that I can control with a servo - PID to manage recycled air vs fresh air temperature. Has anyone else tried this? (Probably only relevant to Europeans paying crazy amounts for power).

All the above apply to the little one but scaled down.

All words of wisdom/guidance will be gratefully received
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