Electrician's formula (7)

Measure the no-load current of single-phase welding transformer without nameplate 380V, and calculate its rated capacity

Formula: 368 welder capacity, no-load current multiplied by five.

Single-phase ac welding transformer is actually a special purpose step-down transformer. Compared with ordinary transformer, its basic working principle is basically the same. In order to meet the requirements of welding process, the welding transformer is required to have certain arc starting voltage when working in short circuit state. When the welding current increases, the output voltage drops sharply. According to P=UI (power is constant, voltage is inversely proportional to current). When the voltage falls to zero (that is, the secondary side short circuit), the secondary side current will not be too large, and so on, that is, the welding transformer has the characteristic of steep drop, the welding transformer's characteristic of steep drop is obtained by the voltage drop generated by the reactance coil. When there is no welding current passing through, the reactance coil does not produce voltage drop. At this time, the no-load voltage is equal to the secondary voltage, that is to say, the no-load welding transformer is the same as the ordinary transformer when there is no load. The no-load current of the transformer is generally about 6%~8% of the rated current (the state stipulates that the no-load current should not be more than 10% of the rated current).

Electrician's formula (8)

Judge ac current and dc current:

The electric pen judges ac and dc, ac bright and dc dark,

Ac neon is bright all over, dc neon is bright end.

Distinguish intersection, direct current, good "two" between the comparison, so it is very obvious. When measuring alternating current, both ends of neon tube are bright at the same time, when measuring direct current, only one end of neon tube is bright.

Partial burning cause of servo motor of ABB robot training

Causes and countermeasures of partial burning of servo motor winding iii

The reason:

Servo motor winding insulation by mechanical vibration, such as the large current when starting, the drag equipment vibration, servo motor rotor unbalance, etc.), and the winding interturn relaxation, insulation as well as the crack phenomenon, accumulating damage effect, heat bilges cold shrink winding due to friction, thus speeding up the insulation aging, eventually led to the first carbonation insulation damage to winding burn.

Countermeasures:

(1) as far as possible to avoid frequent start, especially high voltage FANUC servo motor.

(2) ensure that the dragged equipment and FANUC servo motor vibration value in the specified range.

 

Source: guangke intelligent reprint source