3 phase frequency drive controller exhaust.
I ran accross a frequency drive controller, operating a 3 phase direct drive exhaust motor.
The "Story goes" Sunday a Texas roadhouse called saying their Chargrill exhaust is "shaking the whole restaurant" sure enough the blower wheel is so bably damaged the drive motor lead end is vibrating atleast 2-4" in it's mount
I proceeded to replace the motor and blower wheel that the customer had on hand "as spare parts"
upon restart, the blower came up to speed and blowing good. Case closed, next call......
Later in the day I recieved another call that the store was full of smoke and the exhaust isn't moving enough air
This is where it get's good and frustrating. I've never encountered a frequency drive system before.
Getting back to Texas Roadhouse I eventually found out the blower was running in reverse No problem....switch 2 leads and good to go
NOT! The motor won't run at all except for 1 t1,t2,t3 to l1,l2,l3 connection
I'm tottaly confused/frustrated and pissed at 5:30pm on a sunday night when the restaurant has a line out the door and also full of smoke
So the blower running the wrong way I figured out how to increase the frequency/speed to get enough airflow so they could function. (still in reverse)
I might add... No manual or documentation on the controllers operation
Monday morning: After spending 5 hours at home on my own time till 1 am online I found and learned enough to be able to reverse the motor from the controller but it shuts down after 5 minutes on an error
Found a phone # for Cuttler Hammer Tech. ( the controller's brand)
The Tech. walked me through changing a bunch of parameters and got it running alot better By that time one of my supervisor's arrives (very nice guy!)
He spent the next few hours on the phone messing with the controller and finally got the motor running the right direction at full speed drawing proper amps and moving a TON of air.
Aparently this Adjustable Frequency Drive Controller has some kind of DC feedback from the motor and the field connections to the motor can only be one way and the controller parameters must be changed for direction,speed and such.
Sorry for the long post, In 17 years I've NEVER been so ticked off/frustrated/confused amd felt so helpless at the same time!
They are correct VFD's have feedback from the motor, even though there isn't any extra wires. It does this by monitoring the line and load wires thru the VFD itself.
One thing about VFD's I learned is you have to swap 2 wires on the discharge side of the VFD to change direction if you dont know where to do it in the VFD parameter's menu.
I love to Cook...HVAC is a hobby that pays the bills!
VFD is Excelent device for three phase Motors,I think there are two ways you can vary the output Frequency of VFD.Manual and Auto.In manual Mode you change the frequency by push button or potentiometer on VFD panel or remote in some cases.In Auto mode either trere are some pre defined steps or through Some Sensor like Thermostat,Pressurestat or Flow sensor etc.The Signal from Sensor can be 0-5VDc 0-10VDc or 4-20mA etc.If you have seen some control wires coming from motor itself that can be probably from builtin techometer which is usually not used in exhaust Fan applications.In Exhaust Fan applications either 2 or 3 speeds can programmed or Use Potentiometer so that operator can adjust according to load requirements,If more smoke he can run faster otherwise run slowly and safe energy and cooling also if it is condioned area.
hey exc, was the exhust working right to beging with, did it change by itself? thank god i have not run into this before, is there a picture or a site i that i could go to see one thanks.
Here is a great site for Learning VFD.
Other thing you can do,which Model and brand VFD you have go to that site and download Operational manual of that model and study.If you don't get exect model still other models can also help there is not much difference.Hope
it will help.Good luck.