I am in the process of setting up a blower fan to supply some cooling to the main bedroom in the house, the house has been added to in the past and as a result the main bedroom has no natural ventillation so at this time of year it can be quite uncomfortable, it's not dust collection per se but there's relevence I think; air movement, VFD control, power consumed etc.. sorry if it gets a bit detailed/nerdy.
The blower in question....
fan wheel.jpgdrive side.jpgblower fan.jpg
It (and another) was an auction pickup, not sure but they may be out of the roof mounted evaporative style air conditioner, the plan is to set it up outside and take outside air into the bedroom via some ducting, I'm going to experiment with some thermal mass and water evaporation for some additional cooling.
This wheel type of fan with the forward facing blade design is good for moving bulk volume of air and for overcoming ducting resistance, I did put a piece of ply up to the outlet to block it off which took a bit of effort, I must remember to do a static test at least!!! this fan would be good for ventillation of the shed as well and that is what I will most likely do with the other one I have.
It will be speed controlled via a VFD and a temperature controller, um, all once again gleaned from an auction...
wiring.jpg
The temp controller (lower left in pic) has a digital input and two 0 to 10vdc analog outputs, I just use one that goes to the VFD, (temp above setpoint=speed increase) for the shed the simplest is to just use an adjustable pot. to give a variable output.
Unfortunately it's a bit of a mishmash of voltages, 5vdc from the VFD, 12vdc for the voltage switch, 24vac for the temp controller, 24vdc and 240vac for the relay/contactor coils and 415vac for the fan motor but we got there, a bit more labelling and it will be done!
For additional control I want the fan to turn off when below SP and after a time, this was accomplished with a timer, if above SP the fan turns back on which was done via a voltage switch...
voltage switch.jpg
Jaycar came to the rescue here, it's a kit designed for use in cars to turn a fan on or such dependent on a voltage from a sensor, I am using it here to give me a start signal for the VFD at just above SP (0.3v from the temp controller). The other bit of electronics on the left is a 12vdc regulated power supply and a delay on timer (about 7 secs) which gives the temp controller time to turn on before the voltage switch turns on.
After a few test runs and a few measurements...
data from tests.jpg
At this point all I have done is run the fan as pictured above, the data is taken straight from the screen of the VFD, I then plotted a few graphs, ended up a little messy but I wanted get a visual idea of performance.
Basically I increased speed from 10 to 70Hz by 10Hz increments and then read off the variables as per the table. Unfortunately I don't have anyway of measuring the airflow other than to say it's a nice breeze at 10Hz and at 70Hz it's a fair gale.
One of the VFD setup programmes covers the current draw, the motor nameplate gives 3.6 amps which is the maximum allowable, I can also set the start It2 current and the It2 corner Hz, (t=time) with these three values I can adjust the current trip value at any speedxtime, this sort of programme setting can be good for a motor trip well before the motor lets the blue smoke out,
the current draw is an important number to be aware of especially if we are driving our DC motors at more than the usual Hz.
The power consumed is rather interesting, the table/graph shows as speed increases there is more power consumed per increment, something we know from the fan laws! the kw line looks a little too straight at the end tho, I suspect it might be to do with there being only 1 decimal point on the readout, the %load looks a bit better, I reckon another 10Hz would be about the limit.
Another interesting point is that the motor is rated at 1.5kw, at 70Hz the readout gives 2kw, this extra 0.5kw is most likely due to the fact the motor is not drawing full current and the higher speed above the rated 50Hz, if it was on a larger fan the motor would have reached it's limit before 70Hz. Before I purchased this motor I had a 2pole 2.2kw motor on it as a trial, it did run it but not a good combination, 25Hz was max current draw at 1.1kw from screen readout for this motor, I liken this to driving up a hill foot flat in top gear at 60km.
The motor is a 6pole 955rpm with about 2.2 to 1 drive ratio which gives a fan shaft speed of about 570rpm (from memory) at 70 Hz, there's probably a little more speed in the fan before any big inefficiencies start to arise but I doubt I'll need to run it any faster.
Time for bed
Pete
The blower in question....
fan wheel.jpgdrive side.jpgblower fan.jpg
It (and another) was an auction pickup, not sure but they may be out of the roof mounted evaporative style air conditioner, the plan is to set it up outside and take outside air into the bedroom via some ducting, I'm going to experiment with some thermal mass and water evaporation for some additional cooling.
This wheel type of fan with the forward facing blade design is good for moving bulk volume of air and for overcoming ducting resistance, I did put a piece of ply up to the outlet to block it off which took a bit of effort, I must remember to do a static test at least!!! this fan would be good for ventillation of the shed as well and that is what I will most likely do with the other one I have.
It will be speed controlled via a VFD and a temperature controller, um, all once again gleaned from an auction...
wiring.jpg
The temp controller (lower left in pic) has a digital input and two 0 to 10vdc analog outputs, I just use one that goes to the VFD, (temp above setpoint=speed increase) for the shed the simplest is to just use an adjustable pot. to give a variable output.
Unfortunately it's a bit of a mishmash of voltages, 5vdc from the VFD, 12vdc for the voltage switch, 24vac for the temp controller, 24vdc and 240vac for the relay/contactor coils and 415vac for the fan motor but we got there, a bit more labelling and it will be done!
For additional control I want the fan to turn off when below SP and after a time, this was accomplished with a timer, if above SP the fan turns back on which was done via a voltage switch...
voltage switch.jpg
Jaycar came to the rescue here, it's a kit designed for use in cars to turn a fan on or such dependent on a voltage from a sensor, I am using it here to give me a start signal for the VFD at just above SP (0.3v from the temp controller). The other bit of electronics on the left is a 12vdc regulated power supply and a delay on timer (about 7 secs) which gives the temp controller time to turn on before the voltage switch turns on.
After a few test runs and a few measurements...
data from tests.jpg
At this point all I have done is run the fan as pictured above, the data is taken straight from the screen of the VFD, I then plotted a few graphs, ended up a little messy but I wanted get a visual idea of performance.
Basically I increased speed from 10 to 70Hz by 10Hz increments and then read off the variables as per the table. Unfortunately I don't have anyway of measuring the airflow other than to say it's a nice breeze at 10Hz and at 70Hz it's a fair gale.
One of the VFD setup programmes covers the current draw, the motor nameplate gives 3.6 amps which is the maximum allowable, I can also set the start It2 current and the It2 corner Hz, (t=time) with these three values I can adjust the current trip value at any speedxtime, this sort of programme setting can be good for a motor trip well before the motor lets the blue smoke out,
the current draw is an important number to be aware of especially if we are driving our DC motors at more than the usual Hz.
The power consumed is rather interesting, the table/graph shows as speed increases there is more power consumed per increment, something we know from the fan laws! the kw line looks a little too straight at the end tho, I suspect it might be to do with there being only 1 decimal point on the readout, the %load looks a bit better, I reckon another 10Hz would be about the limit.
Another interesting point is that the motor is rated at 1.5kw, at 70Hz the readout gives 2kw, this extra 0.5kw is most likely due to the fact the motor is not drawing full current and the higher speed above the rated 50Hz, if it was on a larger fan the motor would have reached it's limit before 70Hz. Before I purchased this motor I had a 2pole 2.2kw motor on it as a trial, it did run it but not a good combination, 25Hz was max current draw at 1.1kw from screen readout for this motor, I liken this to driving up a hill foot flat in top gear at 60km.
The motor is a 6pole 955rpm with about 2.2 to 1 drive ratio which gives a fan shaft speed of about 570rpm (from memory) at 70 Hz, there's probably a little more speed in the fan before any big inefficiencies start to arise but I doubt I'll need to run it any faster.
Time for bed
Pete
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