Modern electrical house wiring is built according to certain rules, one of which is the need organization of a water shield and the installation of several automatic devices in it, the main of which are automatic switches. The presence of the latter makes the operation of the wiring much safer, since they remove the power supply from the line in the event of a short circuit.
Correctly mounted and serviceable machine works completely silently. However, sometimes certain sounds such as humming or buzzing appear during its operation. If this acoustic effect is detected, the question arises: how dangerous are these sounds and what to do when they appear?
Humming machine
There can be only one reason for the humming machine: the coil of the electromagnetic release, which is clearly visible in Figure 1. It is constantly under the influence of an alternating current electromagnetic field, and with insufficient pressure spring rigidity, its core begins to oscillate at a 50 Hz frequency. The operation of the coil core in saturation mode and a strong difference in the current shape from sinusoidal can also have a certain effect on the volume of the hum.
The expected life of the machine in these cases can be determined on the bench in the testing laboratory. However, it is extremely difficult to reproduce the appropriate conditions at home. Based on this fact, it is assumed that the buzzing machine is defective and must be replaced immediately, even if it continues to perform its functions and is triggered when the load is exceeded or a short closure.
The requirement for immediate replacement is based on the high density of the visor assembly. Therefore, if one device fails, there are high risks of damage to neighboring ones. Figure 2 shows an example of the consequences of such an event.
Humming machine
The reason for the buzzing (or, alternatively, crackling) is always the same - it is an electric arc that occurs between two conductive elements with poor contact between them. Accordingly, the places of origin of such an arc can be very diverse.
The easiest way to localize the place of arc occurrence is to sequentially turn off the machines. Further, a visual inspection is carried out, paying attention primarily to soot, plastic melting and insulation (Figure 3), as well as to the characteristic smell of burnt plastic.
Most often, the arc occurs in a poorly tightened terminal contact due to poor installation. This defect can be easily corrected by tightening with the required force with an insulated screwdriver.
If, after pulling the terminals, the crackling / buzzing does not stop, then, most likely, the area of poor contact is inside the machine case. Taking into account that the machine is not a repairable item, it must be replaced with a new one with similar characteristics.