Hand welding practice problem_ii - Edwards @ Wiki

1 Structure / function / operation of welding machine

Question 2.1 Current unit: I [A]

Question 2.2 Unit of voltage: V [V]

Question 2.3 Ohm's law: R = \ frac {E} {I} [\ Omega]

Question 2.4 Total value of series connection resistance: R_{a} = r_{1} + r_{2} [\Omega]

Question 2.5 Total value of parallel connection resistance: R = \frac{1}{\frac {1}{r_ {1} + \frac{1}{r_{2}}

Question 2.6 Electronic foundation

1. AC power frequency: 50 or 60 [Hz]
2. Arc discharge: Discharge between welding medium and base metal
3. Rectification: Stable conversion of variable voltage
4. Rated usage rate: usage time per unit time

Question 2.7 Handling of conductors (cables)

1. Electromagnetic induction is generated by the laying of the rotation
   with an excess surplus length to the output cable,
   so output power is secured with an appropriate extra length
2. For the input / output side cable, select the surplus diameter
   against the current used and connect
3. Since a large current flows through the output side cable,
   select a large diameter for the input cable and connect it
4. Cable to weld object side securely connect

2.8 Welding machine usage rate

1. ratio of arc discharge time to unit time

2.9 Measurement of arc power supply

1. The ammeter is connected in series to the arc generation output cable
2. The voltage system is connected in parallel to the arc generation output cable

2.10 Drop characteristics in voltage and current of AC arc welding machine (arc generation)

1. Voltage drop slightly increases current at a specific point

2.11 No-load voltage of AC arc welding machine

1. Voltage at standby time due to welding operation

2.12 Movable core type AC arc welding

1. Control welding current

2.13 Regulation for no-load voltage in AC arc welding machine

1. Measures against high-voltage hazards

2.14 Regulation on voltage of AC arc welding machine

1. The no-load voltage is limited to 80 [V] in the AC arc welding machine
   with the electric shock prevention device eliminated

2.15 Outline of AC arc voltage

1. Arc voltage increases with arc length

2.16 Proper voltage setting in AC arc welding

1. Welding rod diameter 4 [mm]: 30 [V]

2.17 Function of electric shock prevention device for AC arc welding

1. Reduced occurrence of electric shock accidents
   at no-load voltage against waiting time of welding operation

2.18 AC electric arc welding machine

1. No-load voltage: 25 [V]

2.19 Example of usage rate of movable core type AC arc welding machine

1. Usage rate 60 [\%]: Arc generation time 6 [min] / 10 [min]

2.20 Characteristics of AC arc welding machine output cable

1. The output power is decreased with the total length by the rotation laying

2.21 Handling of AC arc welding machine output cable

1. Output current decreases with use of output small diameter cable

2.22 Selection of welding machine output cable

1. As the output current rises with respect to the input current,
   the input side cable is connected to the output side with a large diameter on the output side

2.23 Comparison between DC arc welding machine and AC arc welding machine

1. Arc is dispersed by AC power output to DC arc welding machine
2. Attract magnetic blow by AC power output to DC arc welding machine

2.24 Magnetic blowing

1. The direction of the arc is changed by collision of magnetic flux

2.25 Emergency substitute electric circuit for breakers in distribution box

1. Copper: Because of its high electrical conductivity,
   the current flow increases, causing heat generation and fire
2. Power supply interruption function against overcurrent is lost

2.26 Cause of arc welding accident

1. Cause
   1. Holder connection cable
   2. Welded side connection cable
2. Trouble phenomenon
   1. Difficult to arc
   2. Heating / burning of cable