The Paton Welding Journal, 2013, №01



2013 №01 (10)

2013 №01 (02)

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The Paton Welding Journal, 2013, #1, 2-4 pages  

FEATURES OF CURRENT PROTECTION OF POWER SOURCES FOR EBW

O.K. NAZARENKO, O.A. GURIN and E.I. BOLGOV

E.O. Paton Electric Welding Institute, NASU, Kiev, Ukraine
 
 
Abstract
The purpose of investigations was elaboration of recommendations to reduce disturbances of weld formation during EBW, if current protection of accelerating voltage source has operated because of vacuum breakdown in the welding gun, or if specified value of beam current was exceeded because of short-circuiting in the control electrode-cathode circuit. In view of the random nature of development of the mentioned transient processes, normally-open shorting plug of control electrode-cathode circuit and discharger with adjustable interelectrode gap were temporarily built into the accelerating voltage source between the cable conductor connected to control electrode and ground. This allowed closing any of the circuits and recording load current and accelerating voltage directly during welding, which was followed by comparison of oscillograms with the occurring disturbance of weld formation. It is found that in order to reduce the disturbances of weld formation at breakdown in the gun, the high-voltage source should go into the mode of automatic re-starting during the time of about 0.1 ms. The current threshold of this transition should 3-4 times exceed the maximum load current of the source, allowing for starting current at asynchronous switching on of the power source, and charging currents of capacitances of high-voltage cable and output filter. At short-circuiting in the control electrode-cathode circuit, the accelerating voltage source should automatically go into the mode of beam current stabilization after exceeding its set value by 20-30 % for 3-5 ms. 3 Ref., 1Table, 4 Figures.
 
 
Keywords: electron beam welding, accelerating voltage source, three-electrode emission system, accelerating gap breakdowns, short-circuiting of control electrode to the cathode, physical modelling, requirements to current protection
 
 
Received:                15.10.12
Published:                28.01.12
 
 
References
1. Shabad, M.A. (2011) Maximum current protection. Leningrad: Energoatomizdat.
2. Nazarenko, O.K., Matvejchuk, V.A. (2011) Limitation of overvoltages in high-voltage circuits after discharges in welding gun. The Paton Welding J., 10, 32-35.
3. Lebedev, V.K., Nazarenko, O.K., Lokshin, V.E. et al. Method and apparatus for electron beam welding. Pat. 3042652 DE. Publ. 02.04.82.

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