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| General Electronics Chat This forum is for general chat about electronics, eg: Dont know what a part does? Dont know how to read a circuit? Want to get an opinion? |
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I finally broke down and got a new compressor for my garage. I am a machinist mostly not an electri. any way the compressor I am replacing is 220 volt sears. The new comp. is bigger and says 240 volts, single phase same as the old one. Wired new compressor in place it doesen't work. I am assumeing 220v and 240 v are the same 2 120v lines and a ground. In this case I have a bad motor or just an old fart moment is 220v and 240 volts the same hook up? I have checked the voltage paths with a meter and they are connected correctly lol, all the way to motor. I have even checked how the other compressor is wired they are identical except for this motor on the new one looks cheaply built and has 2 start capaciters on top instead of one on the old compressor. my confidence is now confused lol. can someone set me straight thanks.
I for the heck of it I disconnected 1 120v line from the motor and connected a ground to it and tryed it the motor runs? I didn't run it but for a few seconds but it ran. Im thinking the motor is wired wrong, I did something wrong, bad motor? |
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Make sure both '120 volt' lines aren't on the same phase, which would give you 0 volts phase to phase..this is a common problem when old fuse panels or two single pole breakers are used, they both end up on the same phase and you get 0 out phase to phase and 120 phase to ground..
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gerty |
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thanks, Gerty
I will check into that, I thought just because it worked with 220volts it would with 240 volts. |
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It should work on either 220 or 240..We had a problem once wiring a 240 volt compressor to a 208 circuit..208 is two phases of a three phase system . The compressor hummed when starting , something it didn't do before it was moved. Compressors typically start under load and need full voltage/current.. I'm sure you'll figure it out..
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gerty |
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For the most part, the difference in voltage is just an upgrade in the U.S. power grid. Home voltage is around 120v now, so the two phases together will be 240 v similar to the old 115v/230v system.
If the motor has two capactors on top, one is a start capacitor and the other is a run capacitor, common on larger horsepower motors, especially compressors where you have a lot of starting torque required. Check the voltage on the incoming line side at the pressure cutout switch to see if you have 240 v. If not, check each phase to neutral to be sure you have 120. If both phases show zero, you have a problem either with the wiring or back at the service panel. If one is dead and the other good, you have a blown fuse or a bad circuit breaker. If you have 240v at the incoming side of the cutout switch, check on the motor side of the cutout switch. If there's 240v there, you have a bad motor or it's not wired right -- hopefully the latter is the case. You'll have to check the motor's nameplate to find the wiring diagram and then check "under the hood" to see if it's correct for 240v. Be sure the power is off at the service panel when you're fooling around with this end of things. If the voltage at the motor end of the switch measures zero, check each side to ground. If one is zero and the other is 120v, you have a defective switch. If both are zero, either the switch is defective or there's full pressure in the tank and the switch is in the cutout position. You can check the switch by jumpering across the kpressure switch contacts, one wire from side "A" of the incoming phase to side "A" of the motor and the other wire from side "B" of the incoming phase to side "B" of the motor. Turn power back on at the breaker panel. If the compressor starts up, you have a bad pressure switch. Turn power back off and remove the two jumper wires. Dean
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Dean Huster, Electronics Curmudgeon Contributing Editor emeritus, "Q & A", of the former "Poptronics" magazine (formerly "Popular Electronics" and "Electronics Now" magazines). R.I.P. |
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Hey I found lots of help on motors but I still am not sure how to hook mine up. I want it to open a gate with my 1 hp Baldor motor but Im not sure how to make it for forward and then when told to, to reverse. Some how I have to reverse the power with a circuit.
Other problem is I dont know how to wire it. It is rated for 115/208-230 and I need to know how to wire it for 115... also 220 would be nice if I decided to change my plans to go with more power but might not costs too much for electrical cable. Any help much appreciated! |
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Usually theres a wiring diagram for 12/220V and CW/CCW rotation inside the end cap ( where the wires go in) of baldor motors, info is available on the net for a specific motor number and also at WWW.grainger.com.
A reversing circuit involves 4 wires switched around and you can't sw from forward to backward immediately it is not good for the motor nor the controller . The accepted method is that a controller goes to a neutral position where a set of diodes act as a dynamic break and THEN change direction. Much depends on motor RPMS, if its a gear motor and the current draw. The more info the better. |
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My plan is to have the gate open on say a 55 timer so it opens and then stops, then a delay for 40 sec or a minute.... then to close so it will have stopped for about 40 to a minute.
So I have to some how figure out how to wire it so that I can make it go one way then wait then go the other way. Maybe two different timer circuits will work? |
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The motor is going to be driven by a pully system.
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IT WORKS!!!
The funny thing is I am putting bike gears on the motor (1 sprocket set) and then a chain to another sproket to chain it. I just hope my gate dosent open at the rated 1,725 RPM and that the gears from the bike are enough. Will test it before actually putting the gate to it haha! Thanks TillEulenspiegel PS I went to that site and it didnt really say anything about wiring but the diargram on the motor itself was enough. |
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Hi OXY,
I don't recomend you to transmit power thru a bike chain directly from the motor shaft at 1725 RPM. It would be better to reduce the primary speed via pulley and V belt in at least a 1 to 5 relation and then use the chain and sprocket. From the text, I understand that the gate will return automatically to the closed position after a pre-set period has expired. If it its so, I think that is really dangerous and may cause accidents. Be very careful with this. Regards. |
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hey
yeah I was thinking about that saftey factor. Maybe I should have a remote close too, not sure but I am thinking of using a remote garage door like setup so maybe that would be the safer idea. And the pully way sounds better too. Maybe loosen the belts so that it just has enough tourque to close but if it was to hit something, the belts would just slip. Thanks! Now I just have to come up with a switch that will take 3x3 wires as seen on the motor diagram to allow power one way and then to switch the two wires only for reverse polarity. Kindof hard to explain without looking at the wiring diagram if you follow. |
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That's the EZ part, the safety part is a bit messier. If I get time , I'll shoot ya 1
edit to add: Damn conversion proggie threw out my remarks, which were: M5 and M6 are those numbered terminals on the motor and the X and Y are the wires that went to the terminals , in other words disconnect the wire from term 5 on the motor that wire becomes x, disconnect the wire that went to term 6 that wire becomes Y. The relays K2 and K3 control direction, the relay K1 is the engage relay. Clear at all? limit switch stuff later. |
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thanks buddy, I tried taking a closer look to get a better idea of what you mean but the picture is quite distorted when blown up. Is there any way you could send me a bigger picture? Also there is a total of 6 wires with #5, #8 which switch back and forth. Thanks again!
I think a 555 timer will trigger a triac or a relay which in turn will turn the motor on. The tigger will be a garage door opener sensor system so there is no need to get out to push a button on the gate. Then I am planning on making a keypad with 4 digit code to open the gate for other comers. Lots of work but will be nice when done! |
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