electric motorelectrical
I got this Bergin AC motor which was from a pool pump, but now I want to use it to power a saw.
For this I need to invert its rotation direction. How can I do that by just switching wires?
The four cables at the top just go to the power switch. Unfortunately the metal housing can not be opnened.
Yes, the concave shape should always curve in the direction of the air flow...
(Click to enlarge.)
Switching the L1 and L2 wires wouldn't change the motor's direction and the colors are a bit arbitrary since this is a 220V circuit. Verify that it is 220V and that neither wire is the neutral, then mark the white wire with black electrician's tape to signal that it is "hot" too.
It's a common thing to switch the polarity of the start windings relative to the run windings to change an AC motor's direction. These are usually yellow and orange wires, and the previous installer may have switched these. If you can't tell that this kind of switch was done, don't worry about it and set the new motor's jumper to get it spinning in the right direction.
But, if you aren't certain or comfortable with the situation, have an electrician look it over.
Comparing those tables: Note that the speed switch in the circuit you show isn't using L.
A: L+2+3
B: L+1+3
C: L+1 (Maybe this is L+1+2 ???)
D: L+1+2+3
0: No connection (or no connection to anything but L)
1: 2+1 (possibly plus a connection to L)
2: 1+2+3 (possibly plus a connection to L)
3: 2+3 (possibly plus a connection to L)
Making them correspond with each other...
C is obviously equivalent to 0.
D is obviously equivalent to 2.
That leaves us with
A: L+2+3
B: L+1+3
1: 2+1 (possibly plus a connection to L)
3: 2+3 (possibly plus a connection to L)
We can make those match if we relabel the connections. If we just swap the labels on your terminals 3 and 2, then
A is equivalent to 3
B is equivalent to 1
If we renumbered them all (your 2 is their 3, your 3 is their 1, your 1 is their 2), then
A is equivalent to 1
B is equivalent to 3
Pick whichever you prefer; one will switch off-high-medium-low-off, and the other will switch off-low-medium-high-off.
As far as theory goes: I'm not sure either, but let's see what I can do with it.
3 (2->3) appears to be "slow" because power flows through the right half of the bottom coil, and then through the side coil, in series. More resistance, less current flow, less power.
1 (2->1) appears to be "fast" because the left side of the bottom coil, and the side coil, are powered in parallel. Both get the full house-current voltage applied across them rather than the reduced amount of power they got in series.
2 (2->1 and 3) is the tricky one. I am far from certain, so DON'T take my word for it. But I think what's happening here is that, since the middle and right sides of the bottom coil (1 and 3) are now connected to each other, that loop has a current induced in it by the motor's moving magnets, which creates a countering magnetic field, which acts as a magnetic brake to slow the motor... so fast with a bit of braking equals medium. Seems like an odd solution, but if I'm remembering my freshman Physics at all correctly it might actually be a reasonably efficient solution.
You might want to run this by the physics discussion, to get someone with more recent memory of electrodynamics to check and/or correct that last paragraph.
Gopher baroque...
Best Answer
Single phase, permanent-split-capacitor (capacitor run) motors, like your unit, are normally reversed by switching the roles of the start and run windings. Unfortunately, with the way your unit is wired, it is not possible to make the necessary wiring changes without completely disassembling the motor -- you would have to disconnect the two red wires from each other, then connect the red wire from inside the motor to the terminal that now has the tan wire from the motor on it while connecting the red wire from the capacitor and the tan wire from the motor together, then taking them to where the red wire from the motor now leads.
So, you'll have to head down to a shop that sells motors (industrial-supply places will have them, guaranteed) and get a new motor to power your saw with; either that, or find a way to make your saw work with a motor that rotates the opposite direction from the original.