Microwave ovens are probably the most dangerous of consumer appliances to service. Very high voltages up to V at potentially very high currents AMPs are present when operating - deadly combination. These dangers do not go away even when unplugged as there is an energy storage device - a high voltage capacitor - that can retain a dangerous charge for a long time. If you have the slightest doubts about your knowledge and abilities to deal with these hazards, replace the oven or have it professionally repaired.
Extreme operating environment and more Low insulation resistance in Electric motors Low insulation resistance is one of the most common causes of motor failures and also one of the most difficult to handle.
A low insulation resistance leads to leakages or short circuits in the coils and finally the motor malfunction and failure. When the insulation becomes weak, it eventually breaks down and does not provide the required isolation between the conductors or motor windings.
However, after some time, the insulation starts degrading due to overheating or other undesirable conditions such as corrosion, physical damage and others conditions. To prevent such problems, the maintenance people should perform regular inspections of the insulation.
Electric motor faults due to over-Current An electrical overload or over current condition occurs when excessive current flows inside the motor windings. This is usually more than the design current the motor winding can carry efficiently and safely.
An over current may occur due to various reasons; in particular a low supply voltage will cause the motor to draw more current in an attempt to maintain its torque. Another reason is when there are short circuited conductors, excess voltage etc. An overcurrent condition leads to overheating of the motor and damage to the insulation.
And it is possible to minimize the risk of motor failures due to over current. This can be done by using reliable over current protection, to detect any over current condition, and interrupt the supply and hence stop the current.
Overheating problems in electric motors Overheating in the motor occurs from a variety of reasons, the main one being bad power quality such as overvoltage or under voltage condition. If the supply voltage is higher that rated voltage, the excess voltage is dropped in the motor windings, resulting in to heat dissipation.
On the other hand an under voltage will lead to over current condition which results into more I2R losses in the windings. An over current condition may also happen due to shorted windings or other conditions inside the motor. The other reason why overheating occurs in the motors is the overloading of the motor, or operating the in hot environments which are beyond the motor design or recommended temperature.
A motor with excessive temperatures due power supply or operating environment will fail faster, especially if the rate of removing the heat away from the motor is low. Temperature will continue to increase as the heat generated remains in the motor, causing further increase in temperature and damage to the insulation.
It is recommended to use ventilated areas, ventilation systems of cooling fans if the environment is likely to get hot. An overheating condition existing for a prolonged period of time regardless of the cause will lead to insulation damage and damage to the motor.
A faulty electric motor winding image: In addition, other faults in the motor such as loose bearings, misalignments, and corrosion related issues like wear may cause the motor to have internal vibrations. This reduces the accuracy and efficiency while accelerating the tear and wear on the moving parts that are in contact with one another.
Moisture in AC electric motors The moisture can cause a lot of problems to the motor by causing corrosion of various parts of the motor. In particular, the moisture will corrode the insulation, and lead short circuit between the windings, corrode the bearings, motor shaft and rotors. This will prevent the smooth rotation, decrease efficiency and lead to complete failure of the motor.
Faults in Electric motors due to dirt Dirt such as dust and other debris can block the flow of air in the motor cooling fans, and lead to overheating. In addition, dust particles and other small objects inside the motor may introduce some resistance that will slow down the motor, meaning that it will have to work harder to overcome this resistance.
The dirt particles may also be abrasive in a way to damage the insulation. Conclusion Faults in AC electric motors are caused by simple things and can be prevented through regular maintenance, observing the recommended operating conditions such as well ventilated, dust free environments with no moisture.
In addition, it important to have a stable supply to the motor and the appropriate over current and over voltage protection gear.
Thank you for reading, A. What more can you say about the causes of faults in AC motors?You can plug in with confidence in any region with VV power thanks to our highly-efficient internal universal power supply. With its multi-voltage design, the MGP ensures worry-free operation in potentially damaging environments with fluctuating power levels.
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In certain industries, high voltage means voltage above a particular threshold (see below).High voltage is used in electrical power distribution, in cathode ray tubes, to. Feb 17, · Introduction: By increasing population of the world, towns are expanding, many buildings construct near high voltage overhead power transmission lines.
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Switching Power Supply Topology Voltage Mode vs. Current Mode by: Robert Mammano Unitrode IC Corporation has, since its inception, been active in the development of leading-edge. This power supply outputs one adjustable voltage, which is indicated by the one set of banana jack terminals.
The above arrangement of output terminals with the ground terminal between the + and - terminals is the most common and makes connecting either terminal to ground using a .