- Location
- Placerville, CA, USA
- Occupation
- Retired PV System Designer
Just add more poles!
Curiosity for the day.... How/why did we settle on 60hz and not say 400hz?
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- Start date
- Status
- Location
- Placerville, CA, USA
- Occupation
- Retired PV System Designer
400 Hz has a definite advantage when two conditions are present:
1. There is a high penalty for weight, so the smaller motor and transformer magnertic circuits that 400 Hz allows, based on saturation, is a critcal factor.
2. The wiring is generally small enough that the higher skin effect penalty on conductor ampacity is not a problem.
Where are both conditions present? Aviation for one. Back packed or portable equipment before DC transformation became so easy for another.
I did some experiments with synchro resolvers where one identical unit (the receiver) matches the shaft angle of another identical unit (the transmitter.) They were very small and lightweight because they were designed for 400 Hz excitation. Running them off 60 Hz required a much reduced voltage and greatly reduced the output torque.
1. There is a high penalty for weight, so the smaller motor and transformer magnertic circuits that 400 Hz allows, based on saturation, is a critcal factor.
2. The wiring is generally small enough that the higher skin effect penalty on conductor ampacity is not a problem.
Where are both conditions present? Aviation for one. Back packed or portable equipment before DC transformation became so easy for another.
I did some experiments with synchro resolvers where one identical unit (the receiver) matches the shaft angle of another identical unit (the transmitter.) They were very small and lightweight because they were designed for 400 Hz excitation. Running them off 60 Hz required a much reduced voltage and greatly reduced the output torque.
- Location
- San Francisco Bay Area, CA, USA
- Occupation
- Electrical Engineer
I once did a project that involved making a load bank to test the 120kVA 400Hz generators used on the Boeing 777 aircraft. Each one was about the physical size of a little 1Hp standard induction motor, and that included the CVT transmission it needed to step down from the high shaft speed of the turbines. The alternator itself inside looked roughly like a car starter motor.
petersonra
Senior Member
- Location
- Northern illinois
- Occupation
- engineer
I have designed many load banks over the years. Most for testing aircraft generators and invertors. Don't recall if a 777 was in the group or not.
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