work-piece<\/em> (as opposed to the electrode).<\/p>\n\n\n\nHigher amount of heat on the work-piece would mean deeper penetration of the weld.<\/p>\n\n\n\n
This connection was termed as the straight polarity. In this, the electrode is connected to the negative terminal, while the work-piece is connected to the positive.<\/p>\n\n\n\n
Overtime, it was realized that this concentration of heat on the work-piece is not always good. In case of welding of non-ferrous metals and cast iron, it is problematic if most of the heat is directed at the work-piece. This results in a larger weld pool, which invites hard microstructures in metals such as cast iron.<\/p>\n\n\n\n
Therefore, for such cases where it is desired to minimize the heat on the base metal, a practice began to connect the work-piece to the negative terminal, and electrode to the positive terminal. This polarity is opposite of the earlier practice; hence it began to be called as reverse<\/em> polarity.<\/p>\n\n\n\nMoreover, when covered electrodes came to be in vogue, it was found that they gave the best results under reverse polarity. Hence, slowly \u2013 the reverse polarity came to be accepted as an equally acceptable option, based on the need of the base metal and process.<\/p>\n\n\n\n
In reverse polarity, as discussed above \u2013 electrode is connected to positive, and work-piece is connected to the negative terminal. This polarity is also called DCEP, short for direct current electrode positive.<\/p>\n\n\n\n
Conversely, in straight polarity \u2013 electrode is connected to negative polarity, and work-piece to positive polarity. Hence, this polarity is sometimes also referred to as DCEN, short for direct current electrode negative.<\/p>\n\n\n\n
How To Change The Polarity?<\/strong><\/h2>\n\n\n\nIn the earlier times, the machine would have two terminals \u2013 one positive, and the second negative. The cables headed to work-piece and electrode would be connected to these terminals in accordance with the desired polarity.<\/p>\n\n\n\n
When it was required to change the polarity, the cables would need to be disconnected and interchanged at the terminals.<\/p>\n\n\n\n
In modern machines, a polarity switch is provided which accomplishes this task by simply flicking a switch. This switch is called polarity switch. With this switch, the welder can quickly change the polarity of the current.<\/p>\n\n\n\n
Other Aspects Of The Welding Circuit<\/strong><\/h2>\n\n\n\nThe ammeter in a welding circuit is connected across a high current shunt in the welding circuit. It is basically a millivoltmeter, calibrated to deliver readings in amperes. The shunt is a conductor with very low resistance.<\/p>\n\n\n\n
The voltmeter measures the voltage delivered by the machine. This voltage is same as the one that exists across the welding arc.<\/p>\n\n\n\n
When welding is not under progress, the voltmeter measures voltage across the machine with no current flowing. This voltage is called open circuit voltage, or OCV. The OCV is higher than the voltage observed during welding.<\/p>\n\n\n\n
Another important aspect of an arc welding circuit is the power output of the machine. The power output can be computed by multiplying current and voltage. The result would be obtained in watts. Power can be directly measured too, through a wattmeter. A watt meter is a combination of ammeter and voltmeter, and delivers readings in watts.<\/p>\n\n\n\n
The amount of energy or work delivered by the machine can also be computed by multiplying power with the time for which the power was delivered. This work\/energy is expressed in terms of joules, or kilowatt-hour.<\/p>\n\n\n\n
This was about the arc welding electrical circuit. Please share your thoughts in the comments section below.<\/p>\n","protected":false},"excerpt":{"rendered":"
In order to understand about the polarity in an arc welding circuit, it is first important to understand the construction of the arc welding circuit. This article discusses a few terms used in any electrical circuit such as EMF, current, and resistance. The later part of the article equates the welding electrical circuit to ordinary … Read more<\/a><\/p>\n","protected":false},"author":2,"featured_media":0,"comment_status":"open","ping_status":"open","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[105],"tags":[4],"yoast_head":"\nWelding Electrical Circuit<\/title>\n \n \n \n \n \n \n \n \n \n \n \n \n \n \n \n\t \n\t \n\t \n