This set of questions comes up a lot (in my head) and on occasion here on the forum. The definitive answers seem to always lurk just around the corner but I've never seen them spelled out. So I want to get to the bottom of it.
1. Is the HP of a motor given as the mechanical HP or electrical HP? It can't be both, right? or else it would be 100% efficient.
2. A DC permanent magnet commutator motor can be used as a generator, so long as the brushes are not aligned in a way for use in only one direction (in other words, a bi-directional motor) - correct? I think everybody will say yes, so
2.A. In this case, with your bi-directional DC permanent magnet commutator motor, does it have the same HP as a generator as it does as a motor? Let's say your motor has an electrical HP rating of 2HP and operates @ 180V at full RPM, can you draw 8A from it (2hp)? What if you try to draw 20A? Will the voltage drop or will it burn up or both?
2.B Will the bi-directional DC permanent magnet commutator motor generate the same voltage per RPM as a generator as it would generate RPM per voltage as a motor?
3. How does regenerative braking work? Let's say an electric car has a battery voltage of 300V and max speed of 120mph. When full 300V is applied to the motor, it spins 120mph (ignore gearing, example only). Say this car is going only 40mph (1/3 of max), and coasting, the motor is generating only 100V (1/3 of max) so how can this energy generated by the motor be transferred back to the battery, when it is of lower potential than the battery?
4. how on earth does polyphase induction motor function as a generator? I know they use it in windmills. I have read about it before and I know that the motor has to be spun faster than synchronous speed, but I did not understand the material. It made me think that current flows in 2 different directions simultaneously in the same winding; once to induce current into the rotor, and then again in the opposite direction as the rotor induced current back into the winding. I do not understand.
1. Is the HP of a motor given as the mechanical HP or electrical HP? It can't be both, right? or else it would be 100% efficient.
2. A DC permanent magnet commutator motor can be used as a generator, so long as the brushes are not aligned in a way for use in only one direction (in other words, a bi-directional motor) - correct? I think everybody will say yes, so
2.A. In this case, with your bi-directional DC permanent magnet commutator motor, does it have the same HP as a generator as it does as a motor? Let's say your motor has an electrical HP rating of 2HP and operates @ 180V at full RPM, can you draw 8A from it (2hp)? What if you try to draw 20A? Will the voltage drop or will it burn up or both?
2.B Will the bi-directional DC permanent magnet commutator motor generate the same voltage per RPM as a generator as it would generate RPM per voltage as a motor?
3. How does regenerative braking work? Let's say an electric car has a battery voltage of 300V and max speed of 120mph. When full 300V is applied to the motor, it spins 120mph (ignore gearing, example only). Say this car is going only 40mph (1/3 of max), and coasting, the motor is generating only 100V (1/3 of max) so how can this energy generated by the motor be transferred back to the battery, when it is of lower potential than the battery?
4. how on earth does polyphase induction motor function as a generator? I know they use it in windmills. I have read about it before and I know that the motor has to be spun faster than synchronous speed, but I did not understand the material. It made me think that current flows in 2 different directions simultaneously in the same winding; once to induce current into the rotor, and then again in the opposite direction as the rotor induced current back into the winding. I do not understand.