Bridge crane electrical fault phenomena and causes

  A main motor circuit generally comprises the main motor winding resistance box in series resistance, the control box in the AC contactor and the linkage lines. Because  overhead gantry crane  during normal working hours, the resistance of the resistance group box most of the time put into operation and will therefore generate a lot of heat, so that the resistance groups at higher temperatures. At high temperatures, either itself or resistor resistor connection terminals are perishable. On the one hand will change the resistance material, causing a qualitative change in resistance resistance: resistance connection terminal on the other hand may lead to rupture of the motor rotor or stator series resistance unbalance. At the same time,  hoist gantry crane  work process various AC contactor switching frequency is particularly high, and its contacts can easily be in frequent switching of injury, aging, resulting in some contact resistance becomes large or the occurrence of phase phenomenon, so the series resistance of the motor winding resistance unbalance. In both cases, the  bridge crane  overload or working long hours will cause motor damage and other faults.
   (2) the main power supply system failure is mainly powered trolley line failure. If caused by a trolley line power interruption, significant deformation caused by the electrical conduit can not move the brush side of the granular surface abrasions and pits, ducts shaking too much work, brush wear too fast, there is a large electrical glide sound and shell scratches. The reason is often caused by improper installation of rail deformation caused by thermal expansion of the ambient temperature is too high stuck phenomenon by incorrect electrical installation and positioning deviation.
   3. The electrical system of the electronic components of quality problems can cause the main motor and other electrical damage. Such as the poor quality of AC contactor, mechanical reliability is not good, coil heat, pull bad and coil burnout; various protection relays poor quality and damaged. Some AC contactor low silver content or use copper iron copper contacts, contacts or use of recycled plastic shell thin plastic, resulting in poor contact contacts, sparks and easy melting, three-phase contact spring pressure inequality and shell rupture.
   4 Power supply voltage decreases. As the main motor (lifting motor) power (typically more than 15 kW), but also a full voltage starting, if the bridge crane mounted farther to pitch power transformer or dedicated power supply line equipped with other high power appliances, and optional power supply line when the diameter is small, the power supply voltage decreases will, sometimes resulting in reduced power supply voltage is greater than 10% of rated. Supply voltage is lowered is bound to make the motor starting time longer or cause starting difficulties, can lead to motor damage.