A two phase AC motor

[zape]

I also posted this message in the electrical motors engineering forum but being a 400Hz question and this the aerospace forum.... who knows!!

"I have a very old design (from the 70's) and the information I have is pretty poor.

The schematics show a two phase AC motor which is supplied with a reference voltage of 26V@400Hz. A second voltage, used for control, is a 400Hz signal with a maximum of 13Vrms.

I do not have any information about the relation of phases between the two signals and even more frustrating, in the drawings the motor seems to be based in a three phase motor having two of the windings connected in parallel. These parallelized windings are fed with the control signal (13V@400Hz).

Any idea/advice about the type of motor and control will be appreciated. Obviously I don't have the motor in my hands, so any measurement can not be done before two/three months.

Thanks in advance."

 

[FieldTeam]

It sounds like a servo for an autopilot system. The reference 26VAC fixed phase must be excitation and the control would be directional/variable phase relationship controlled from a control amplifier.

There should also be additional components to a servo like this, such as a rate generator, follow-up mechanism, capacitor and torque limiting device.

The type I am used to seeing operate on 115VAC 400hz excitation and a variable phase/voltage from the control amp. The phase and amplitude would determine the direction of turn and torque.