Overheating of DC motors is mainly due to:

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ALP CBT 2 Electrician Official Paper (Held On: 23 Jan 2019 Shift 3)
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  1. Rough commutator 
  2. Overloads 
  3. Loose parts
  4. Absence of brushes

Answer (Detailed Solution Below)

Option 2 : Overloads 
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There are typically five main reasons for overheating are given below

  1. Overload
  2. Poor power condition
  3. High effective service factor
  4. Frequent stops and starts
  5. Environmental reasons

 

  • Over Heating in motors can cause a number of performance problems.
  • Overheating causes the motor winding insulation to deteriorate quickly.
  • For every ten centigrade rise in temperature, the insulation life is cut in half. It has been concluded that more than 55% of the insulating failures are caused by over-heating.
  • Every electric motor has a design temperature. If a motor is started off at a bad current value, it starts operating in a much warmer condition than the design temperature.
  • It is very important that the motors should be matched with their ideal current values.
  • Overheating also occurs when an electric motor is forced to operate in a high temperature environment. This causes the rate at which heat can be conducted to reduce at an alarming rate.
  • The area where electric motors are operating must have a proper cooling system and a ventilation system should be there in case the cooling system stops working.
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