What happens when a motor goes dead?
George Gonzales covered the first question pretty well.Many home appliances like vacuum cleaners, food mixers and power tools have universal motors. They are like DC motors. They have brushes that can wear out or stop making contact. Brushes are replaceable, and older appliances used to have two little round covers that you could unscrew to replace the brushes. Now, you need to take the appliance apart and unsolder the brushes. That is probably the most simple repair that can be done, but even that will usually cost more to pay someone to do than the price of a replacement appliance. Because of that, there are few if any places to get something like that repaired.If there was any odor or smoke involved in the failure, the insulation on the motor windings is probably burned. Even if the insulation has not burned to the point that there is a short circuit or open wire, that would happen soon if the protection is reset or replaced and the motor operated again. Repair would mean re-winding or replacing the windings. The cost is above or near the cost of a new appliance, so no one offers that kind of repair except for much larger industrial sized motors.Sometimes the bearings lubrication will get bad or cooling air will get blocked from going through the motor by dirt or something. That will make the motor overheat. When that happens, a thermal fuse buried inside the motor will blow and shut the motor off. The thermal fuse doesn't cost very much, but it takes time and a certain amount of skill and patience to replace it. With practice and the knowledge of how to quickly take apart and re-assemble a lot of different products, someone could make a living doing that kind of repair, but there would need to be a lot of people willing to bring things in to save just a little on repairing something that may or may not be easy to fix.In a refrigerator, dish washer, laundry washer or dryer, replacing a small relay or switch may bring the appliance back to life at a fraction of the cost of a new one. Even then, it is probably more profitable to sell refurbished appliances than to go to people's houses and repair them.
What are the advantages and disadvantages of transformer?
Advantages:*High efficiency.(comparison)*No moving parts.*Less capital cost.(comparison)*Less maintenance cost.(comparison)*Easy to move.(comparison)*Easy to add and remove.*Easy to increase or decrease voltage.*Less monitoring required.*No starting time.Disadvantages:*Emits heat and requires a cooling system.*Works only for ac supply.This device is the most efficient device to transform voltage during transmission of ac power