I have a Galley Maid 12 volt windlass on my trawler. It has a DC motor with separate terminals for the field winding (F1, F2) and the armature (A1, A2). Measuring the terminal voltages under load, I'm getting readings of about 6 volts on each set of terminals. The polarity on the armature winding reverses to change rotation direction.
My first reaction at seeing 6 volts was that I was getting a lot of voltage drop somewhere in the cables, controller box or terminals. Now that I take a close look at the controller circuit however, it looks like the field and armature windings end up in series instead of parallel. If that is in fact the case, 6 volts at each winding would be just about right.
Is there anyone here familiar with the normal way of connecting up the field and armature windings on DC motors?
Richard J Kinch 1 April 2005 08:40:21 [ permanent link ]
Wayne.B writes:
Is there anyone here familiar with the normal way of connecting up the> field and armature windings on DC motors?
Can work either way, series as you say you have, or parallel. Series vs parallel yields different speed/torque characteristics depending on which way it is wired, so which you want depends on the application.
Meindert Sprang 1 April 2005 10:09:50 [ permanent link ]
"Wayne.B" <waynebatrecdotboats@hotmail.com> wrote in message news:4bip41t0nrqp5lai524elab5i4n9rs1dpd@4ax.com...> I have a Galley Maid 12 volt windlass on my trawler. It has a DC> motor with separate terminals for the field winding (F1, F2) and the> armature (A1, A2). Measuring the terminal voltages under load, I'm> getting readings of about 6 volts on each set of terminals. The> polarity on the armature winding reverses to change rotation> direction.>
My first reaction at seeing 6 volts was that I was getting a lot of> voltage drop somewhere in the cables, controller box or terminals.> Now that I take a close look at the controller circuit however, it> looks like the field and armature windings end up in series instead of> parallel. If that is in fact the case, 6 volts at each winding would> be just about right.>
Is there anyone here familiar with the normal way of connecting up the> field and armature windings on DC motors?
This is called a series motor. Shunt (=parallel) motors do also exist, as well al compound motors which have both. But the wiring method is not interchangeable. If you have a series motor, you cannot rewire it to be a shunt motor because the field windings are different for both types. A series motor has only few fiels windings of thick wire while a shunt motor has many field windings of thin wire. Applying a series field winding as a shunt will simply be a short-circuit and blow (hopefully) your fuses. The advantage of a series motor is a high starting torque, but the disadvantage is that it runs away with no load, until it explodes into bits.
