motor wiring question

[jrc2905]

I have a book, Electricity and Controls for heating, Ventilation, and Air Conditioning, from Delmar Publishing. In the sections that deal with start relays, it shows its motors using common connected to a neutral (page 129) when using 120 v and common connected to L2 when 240V. All my other books use common for the 120V line or L1 when using 240V. This is the reverse of everything I have seen when wiring motors, what is up with this?

[ct2]

On a single phase 220 volt circuit there are three wires. usually a black a red and a white -white wire will be the common- the red will have 110 potential volts -the white will have 110 potential volts -AC-

so if we are talking about two motors side by side that are 110 volt motors- you would connect the hot red on one motor and the hot black on the other motor and the common wires can all be connected together

I guess I could have said that the red and the black are two seperate 110v-ac lines-however in the power panel you will find the two hot wires connected to the same breaker

[millerman]

Originally posted by jrc2905
I have a book, Electricity and Controls for heating, Ventilation, and Air Conditioning, from Delmar Publishing. In the sections that deal with start relays, it shows its motors using common connected to a neutral (page 129) when using 120 v and common connected to L2 when 240V. All my other books use common for the 120V line or L1 when using 240V. This is the reverse of everything I have seen when wiring motors, what is up with this?

120v indeed uses common to neutral. 240 common is L1 or L2 as they reffer common as a constant voltage potential and the other line going to a relay to complete the circuit when called.

[ct2]

btw page 129 in my book talks about commercial control systems- I have the 6th edition

[jrc2905]

My book is the second edition. I was looking at the motor as if it was a PSC hermetic compressor motor. What I was trying to find is a wiring diagram that shows the wiring for a PTC with a hermetic compressor.

[Edited by jrc2905 on 04-06-2005 at 02:14 PM]

[beenthere]

Many 240 volt multi speed motors will label the white wire as common, the black, red, and blue are your speed taps.

It just means that the white wire is hooked to the contactor, and which ever speed tap.


Check out the brown cap wires, ever wonder about the brown wire with the white stripe.

[wormy]

long day.... brains went numb....

Someone refresh my memory.

A PTC capacitor is the little blue one with terminals on each end and one on the side right? Has a jumper you put between each end terminal... Think Carrier used them alot about 10-15 yrs ago maybe

Am I on the right foot?

[beenthere]

Carrier,York, and others have used them, York still does.
There blue, or black.
Has a heater in it to drop it out of the circuit, after the compressor starts.

[jacob perkins]

Originally posted by jrc2905
My book is the second edition. I was looking at the motor as if it was a PSC hermetic compressor motor. What I was trying to find is a wiring diagram that shows the wiring for a PTC with a hermetic compressor.

[Edited by jrc2905 on 04-06-2005 at 02:14 PM]

I dont have the book you are talking about ,but I will attempt to answer anyway. The ptc is connected across the run capacitor.

[jacob perkins]

Originally posted by wormy
long day.... brains went numb....

Someone refresh my memory.

A PTC capacitor is the little blue one with terminals on each end and one on the side right? Has a jumper you put between each end terminal... Think Carrier used them alot about 10-15 yrs ago maybe

Am I on the right foot?

yes,that is right wormy.do you replace them,or pull them off and use a supco hard start?

[jacob perkins]

Originally posted by jrc2905
. All my other books use common for the 120V line or L1 when using 240V. This is the reverse of everything I have seen when wiring motors, what is up with this?

It doesnt matter.(As long as you dont cross them)