Q:If an induction motor is rated at 0.5HP and 370W at 220V single phase, is this just at start up or when under operating load. In this instance it's a submersible water pump designed for continuous duty operating on a power curve with a maximum flow rate of 400Litres/min and maximum dynamic head of 14.5 metres. Apart from general interest my main reason is that I want to get some idea of the operating costs of running this pump to supply my pond waterfall on a 24/7/365 basis.

In the case of submersible pumps for wells, the motor efficiencies usually are even lower for a given motor size. It may be due to the constraint that the motor has to fit in a small-diameter well casing. It could also be due to the motor manufacturer being able to get away with producing a low efficiency motor since the liquid in which the motor is immersed will conduct away the waste heat. And submersible motors tend to be exempt from efficiency requirements.

Q:will a brushless dc motor work underwater if you just varnished/sealed/coated the windings?

Underwater Dc Motor

Q:what are the important uses of dc generator and dc motor?

dc generators have been mostly supplanted by more efficient alternator style generators. this is particularly true where the mechanical rotation speed has to vary over a large range, such as an automotive engine. dc motors have historically been prefered for applications requiring high power and smoothly variable speed. AC motors tend to work best when rotation is locked to the phase of the line frequency. dc motors can have the speed smoothly adjusted and in some applications can also act as a dynamic brake for slowing, a good example is the motors used in railroad locomotives.

Q:Winding of single-phase AC motor?

Depending on the type of motor, the range motor is the same as you say. Asynchronous motors are not like this.

Q:I want to run an AC motor submerged in hydraulic oil. What do I need to do?

Verify that the pump seals and gaskets of a sumersible motor/pump assembly are rated for the fluid being pumped. You may need to order a unit with teflon vs. rubber seals for example....

Q:i have a motor that need dc current but i don't have the equipment with dc i have only ac. what is the difference of ac and dc

AC voltage alternates polarity 60 (50 in Europe) times a second, meaning the AC current changes direction that often. Only AC is good for transformers, and AC motors tend to be more efficient and constant speed. You just need to know what DC voltage you need for the motor. If it's 12 volts, most people will just use a car battery for a source. You can hook batteries in series for higher voltage. You can also buy power supplies that turn AC into different DC voltages.

Q:what is the connection of single phase AC motor rew and fwd?

In AC single phase motors to reverse the direction of rotation of motor, you have to reverse the direction of the magnetic field. To reverse the direction of magnetic field interchange the winding wires.

Q:How to distinguish AC and DC machines

This also increases the manufacturing cost of DC motors to a certain extent. The alternator is concerned, it can realize direct energy feedback to the grid (but must ensure 4 conditions: the same voltage amplitude, phase and phase sequence of the same, the same frequency); but DC generator power needs to convert AC inverter (DC rectification process called, the direct current into alternating current the process that the inverter can be feedback to the power grid). So it also needs to increase the power of the inverter.

Q:What is the size of DC motor and AC motor under the same power?

The output power is the same, and the DC motor is small.. The power consumption is the same as that of AC motor.

Q:How does one calculate the stator (or rotor) phase winding resistance (NOT impedance) of an AC 3 phase motor?

Firstly, we have to establish if this is single speed, or two speed? You have said it is a squirrel cage motor, therefore can assume to be an induction motor. Because the starter has 3 contactors, you cannot assume it is a Star/Delta started motor, even if one contactor has a star connection. A 3 phase induction motor, with, or without a star/delta starter should never have any resistance between windings if all external connections are disconnected, which you obviously appreciate. There does exist a type of motor called a tap wound, or Dahlander motor. This is a 2 speed motor with 1 x 3 phase winding. The windings are connected internally, using 3 contactors to give a pole change in ratio 2:1 using delta and star/star (Double star) configurations. Afraid not enough information is supplied, however if it is a single speed 3 phase induction motor, you have a problem with the motor, sorry. Try the site below for winding connections, I have eventually found. Good luck Chuck.