Winding short
A winding short (a combination of the words winding and short circuit ) occurs when various windings of an electrical machine are electrically connected due to an insulation fault .
The winding short has different effects depending on the machine and the fault location:
- Failure of part of the winding (loss of performance)
- Removal of galvanic isolation (loss of operational safety)
- Short circuit with destruction of the windings (complete loss of function and fire hazard)
root cause
The main reasons for a winding short are (multiple reasons are also possible)
- Aging of the insulation materials
- Overload due to improper use of the machine
- Overheating of the winding due to incorrect or missing cooling (ventilation defective, slots clogged, dirty)
- Improper, amateur repair of machines
- Incorrectly set voltage setting ( slide switch , rotary switch at the voltage input)
- Operation in the wrong environment (e.g. in salty air or in the tropics with high humidity)
- Incorrect voltage at the connection
- Insufficient fixation of the winding by impregnation varnish
detection
In terms of measurement technology, the winding short can be detected via a resistance measurement and / or a high-voltage measurement. In addition to multimeters or ohmmeters, measuring devices are also measuring bridges and high-voltage measuring devices (only qualified persons ). A winding short can also be recognized acoustically under certain circumstances. An affected motor may generate humming noises during operation.