At present, the voltage level in the welder equipment in the society is 380V, and in the mine underground construction, it is often because the downhole voltage is 660V and cannot be used directly.In previous underground construction, a series of two welding machines and 380V power supply from the ground were used.Not only the effect is not good, but also reduce the equipment utilization, make the construction equipment insufficient problem more outstanding.Can you solve this problem?Through the exploration and practice, we use a BX3-400 ac arc welding machine, which can meet the requirements of 660V under the downhole by changing the connection of its internal winding.This method is used for the first time in underground construction of canal main shaft.
1.The BX3-400 arc welding transformer is an enhanced leakage - moving coil arc welding transformer.It can be seen that both primary and secondary windings are divided into two parts.It is fixed at the bottom and center of the core column, and the coupling process of the two can be changed by turning the screw on the handle to achieve the purpose of regulating the current size.Primary and secondary windings can be controlled by switch respectively connect in series (connection Ⅰ) and (Ⅱ).The number of turns of primary and secondary windings is approximately equal when connected in series.So the secondary voltage doesn't change much, but at this point the reactance is about four times as high as in parallel, which is a quarter of the welding current.Therefore, the adjustment range of the current can be greatly expanded when the connection method of the primary winding is changed.
2. Modified method of 660V welder.As is known to all, to make the modified electric welding machine can be used under 660 v voltage normal, first must meet the following two conditions: first, a modified electric welding machine coil bear 660 v voltage, electric current is less than the rated current of the original electric welding machine.Otherwise the coil will be worn and burned.Second, the no-load voltage of the modified welder should be between 60V and 80V.Because more than 80V will be harmful to personal safety, less than 60V will be difficult to meet the welding process requirements.Therefore, integrated the original welding connection Ⅰ and connection characteristics of Ⅱ will welding machine coil a concatenated to the side, and the secondary side and pick, to reach the above requirements.
The feasibility of the refitting welder is theoretically calibrated.We select the maximum working state of the welder to prove it.
2.1 voltage check.
From the front BX3-400 welding machine principle, can be seen in the structure, the welding machine in connection Ⅱ, a coil and on 380 v power supply.So come to the conclusion that electric welding machine, each coil pressure is greater than 380 v, and modified welder, a coil is concatenated on 660 v power supply, each coil only bear 330 v voltage, less than 380 v, so to be able to meet the requirements.
2.2 current check.
A, the maximum working current I2 = 400 welding machine, according to the current ratio is equal to the voltage transformer is law concluded: = 75/380, 11/400, 11/79, because at this time for parallel at A time, so only half under each coil current of 39.5 A.The modified welder: I '1/400 = 660/65, I' 1/=39.3< 39.5, so it can meet the current requirement.
2.3 the calibration of the no-load voltage is due to a string of 660V power supply, so the voltage of each coil is 330V, according to the number of turns before modification.330/380=V '2/75 u' 2= 65V, so it can satisfy the requirement of the electric welding machine's no-load voltage between 60V- 80V.
3. Conclusions and recommendations.
3.1 the conclusion
It is proved by theory that the modified welder can adapt to the working voltage of 660V and has the same performance as the original welder.The test results show that the no-load voltage of the welding machine is 63V, and the current is between 150~400A and can meet the demand of the downhole welding operation, and it has good welding characteristics.
(1) it can change the tap of a coil to improve the no-load voltage if it is considered to be low.
(2) a switch switch can be installed on the welder to change the wiring.So that's 380V and 660V.
(3) because the voltage is doubled, the requirement for insulation is higher, and it is better to increase the spacing of the two terminal columns at one time.