Superflow SF300 motors, motor performance issues, & motor wiring
-Five wires:
-the two small red wires connect to the thermal limit switch.
-the large blue is a common----where one wire from each of the 8 motors all connect in the center of a junction block.
-the large red is 110V that connects to one wire from each of 4 motors.
-the large black is 110V that connects to one wire from each of the other 4 motors.
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-the 7 small plastic tubes all connect to the manometers and to the open ends of small brass tubes that are inside the plenum.

-The junction block has one wire from each of four motor on one end connected---and connected to the black power wire.
-One wire from each of all 8 motors are all wired to the center section and connected to the blue “common” power wire.
-Then the other end receives the wires from the other 4 motors connected to the red power wire.
-The power supply from the wall is a 220 volt 3 wire 50 amp plug---where the bottom blade is the common and each of the angled blades is a 110v supply.
-The motors are 110 volts and when tested individually using a 110v supply show a 5.5amperage draw.

-The looseness of wires inside the motor compartment have been drawn together and then plastic wire ties were used to keep the wires relatively snug.
-These wire ties are very sharp so I have included a photo of just how dangerous they are.
-Part of my expedition and exploration here was to remove each of the 16 brushes, inspect them and pass judgement as to whether they should be replaced.
-But within the first few minutes my hand was bleeding-----so I cut all of those wire ties ---got them out of there until I was done---then I rebundled the wires and put new wire ties back in when I was finished.

ABOUT THE MOTORS
-I had been told that SF300‘s had 6 motors that were Ametek/Lamb #115923---supposedly consume 10.8amps with 100.4” H2o (inches of water) suction, and use special wide carbon brushes Ametek #33392-11 (have to call Grainger for prices).
-I found that my bench had 8 motors #115750----that were supposed to use 8amps with 92” H2o suction---brushes are Ametek #33308
 -I tested one of the 115750 motors and found it used 5.5amps with only 42” H2o of suction.
-I had bought 12 new #116884-49 (freight salvage) motors ---specs say 9.5 amps with 96.4” H2o suction, and use #33308 brushes.
-I tested all of these and found they all used 8.5 amps with 80 to 82” of suction.
-The Ametek brushes cost about $6.50 each in the Grainger catalog and supposedly have a 500 hour life span.
--I had paid just $66 total for the 12 motors so at first I was happy that I at least now had brushes that would fit my old motors----then when I found the additional performance difference that was like a bonus.
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-The motors are siliconed onto the mounting bulkhead---and also held in place with one wooden bracket and two 1/4nc bolts for each pair of motors.
-To remove the motors looks like it’s going to be a major job---where maybe a thin flexible paint scraper with the edges sharpened could be used to slice thru the silicone.
-the 8 motors up inside the SF300 motor compartment.

DISCUSSION ABOUT MOTOR PERFORMANCE AT ALTITUDE
-when I was testing the 116884-49 motors they were supposed to have a suction of 96.4” H2o but what I saw was about 80 to 82” which is 14.9 to 17% less than specified.
-So this got me to wondering why and this is my best explanation:
1-I live at approximately 4200 elevation where the barometer is about 25.65”HG (mercury) compared to sea level which is 29.92”HG.
I feel the difference in altitude easily accounts for about 14.3% just because of the barometer differences.
3-The difference between using 8 of the 116884-49’s having 80 to 82” suction versus the 42” suction of the original 115750’s looks like the 116884-49‘s” should be worth 1.9 times the current airflow of my SF300 flowbench----if I can justify the effort to go thru the removal of the original motors.

SuperFlow 300 Motor Wiring

Bill Jones' Photo Gallery Page 16