Question concerning AC vs DC servo motors

[glengeniii]

I'm curious to know why AC servo motors always have a specified power rating listed (watts) and DC servo motors never have a power rating listed, only their volts and amperage.

Is it safe to say that a DC motor that is rated at 100vdc and 5amps, can do about the same amount of work that a 500watt AC servo motor can do?

Thanks

[ee_t]

You would have to factor in the efficiency, as the AC motor is likely rated 500W output, and the DC you are taking 500W input.

So looking at the KL34-180-90 for example:
constant torque: 226 oz-in
speed: 3200rpm
voltage: 90V
current: 7.8A

Input power = 702W
Output power = 535W
Efficiency = 76%