Q:My AC stopped working a few months back, got the HVAC guy to come out and he said that the fan motor had gone out on one of the units (we have two) so he replaced it but ever since he did that , the AC will trip at the circuit almost everyday, sometimes a few times a day. When I looked at the old fan motor vs the new one, it looks as if the new one is higher HP 1/4 vs 1/6 and also more AMPs 1.8 vs the old at 1.0. or my other guess is that the shut of switch next to the ac units , one of them looks a little melted and the metal plate is slightly turned due to it. ( not sure if that is the correct name for it but it has a plastic handle that you can pull to shut of the AC unit right there). Any help would be appreciated. Thanks

The motor size increase in itself should not be an issue. .8 amps is minimal on a circuit rated at 30 amps(thats a guess depending on what your actual circuit load is). The disconnect switch on your wall may very well be the culprit. Weak connections can cause over amperage conditions to occur very easily. A bad contactor(the part that energizes and pulls in to turn on the compressor) will cause over amperage and/or voltage imbalance as well if the contacts are severely pitted and/or burned. I suggest powering off the unit at the breaker. Go through all the electrical connections and check for tightness at the lugs. Look for any wiring with broken insulation that could be touching metal intermittently. Take a closer look at the disconnect and look for wiring with melted insulation or fuse holders that are loose or look overheated. (a disconnect can be found at Home Depot). Good luck.

Q:Why in general larger aircraft make use of both AC and DC electrical systems.?

AC motors and controls can be made smaller and lighter, especially when driven at 120V and 400 hz. Almost all, if not all, systems that are intended for normal use with normal power will be AC. DC, on the other hand, is the old stand-by when down to just battery power. If a pilot arrives at a dead airplane, with no external power (AC), how will he get the thing running if it requires A/C? With one or two batteries, one DC fuel boost pump, a DC starter on the APU, DC fire detection and DC fire fighting systems, he can safely get the airplane up and running, and if a fire breaks out during the process, he can fight the fire. If there is a loss of all AC generators, then there needs to be some DC powered stuff from the battery (basic flight instruments, basic lighting, etc.) to allow continued flight while attempts are made to restore the AC. On the Boeings, the fallback really important stuff will be found on the hot battery bus, battery bus, DC transfer bus, and standby DC bus. The Airbus probably does the same thing using different names.

Q:my AC motor have 2800 rpm but i need 1500 to 1800 rpm which will be variable value.i can control rpm my self 1500 to 1800 which i need.how can i do this?and is this effect on life of motor?

Reduce speed on the driven equipment by using reduction drive pulleys. The driven pulley should be twice the diameter of the drive pulley.

Q:It's quite a newbie question x_x there is a label on the motor I've got (top image) and it has 3 inlets for wires. 2 white wire go into the middle inlet and one blue for each left and right inlets.I presume the middle one is for the neutral and either left or right is for the phase wire.Thanks in advance :)

Connect the 220 volt power to terminals 1 and 2. Terminal 0 is not connected.

Q:Im trying to make tattoo gun what would be a better motor 18volt ac or 18 volt dc?

DC because it's safer. If you don't know what you are doing you could kill someone with ac, even at 18 volts.

Q:I like to do like home project to boost my mind and I seem that ac motor can be used as a generator as long has you turn it the other way. I was a industrial ac motor and would like to see if I can use it for my project to built a generator

An induction motor won't work well as a generator. A synchronous motor can be used as a generator.

Q:What are the speed regulating methods of AC motors? Detailed point

1. use frequency changer to change power frequency speed regulation, speed range is wide, stability smoothness is better, mechanical characteristic is hard. That is, with the rated load, the speed drops much less. Stepless speed regulation. It is suitable for most three-phase squirrel cage asynchronous motors.2., change the magnetic pole logarithmic speed regulation, belong to level speed regulation, speed adjustment smoothness, generally used in metal cutting machine tools.3. change slip speed regulation.

Q:Why are DC motors more powerful than AC motors of the same power?

Because the motor armature circuit resistance and inductance are small, and the rotating body has certain mechanical inertia, so when the motor is switched on, starting the beginning of the armature speed and anti electromotive force of the corresponding small starting current, large. Up to 15~20 times the rated current. This current will disturb the power grid, the unit will be subjected to mechanical shocks, and the commutator will spark. Therefore, the direct closing start is only applicable to motors with power not greater than 4 kW (starting current is 6~8 times the rated current).

Q:I know many AC motors don't have brushes but there are some that have brushes. How do you call that type of motor? Thanks!

There is such thing as a brushless motor!. Although i think they are only DC motors that are brushless and used in things like your desktop pc as cooling fans

Q:The difference between DC motor and AC motor

Master formulas n1=60f/P, S= (N1-N), /n1, n= (1-S), 60f/P, and understand their meaning (very important), and be able to flexibly use these formulas for calculations. Also remember: the slip rate of the motor at normal load is approximately SN, 0.01-0.06. The examples in the book should be emphasized.