For AC machines, the torque and speed can be also expressed in pu.

The nature of the AC machine with a large transformer also made these units very hard to transport, and they tended to be large units on wheels.

Flux linkage is commonly used to estimate the magnetic flux of an AC machine.

The AC synchronous machine is the most common technology for generating electrical energy.

It was used extensively to explain the properties of salient-pole AC machines.

Now there is more interest in superconducting AC synchronous electric machines (alternators and synchronous motors).

The rated voltage of the three-phase AC asynchronous machine and the traction current machine is 12.5 kV.

For instance, VL80 is an AC machine, with VL10 a DC version.

However, an AC machine must match both the amplitude and the timing of the network voltage, which requires both speed and excitation to be systematically controlled for synchronization.

Eventually, the General Electric company (formed by a merger between Edison's companies and the AC-based rival Thomson-Houston) began manufacture of AC machines.