Welders & Filters Flashcards
What are the most important ratings when replacing resistors
Power
Resistance
Tolerance
The maximum voltage
What is the fourth band of a resistor represent?
Tolerance
Three characteristics that affect the capacitance of the capacitor:
Surface area of the plates
Distance between the plates
Dielectric constant between the plates
Electrolytic capacitors are polarity sensitive. T or F?
True
A capacitor can be used as what sort of device to block dc and pass ac if placed in series?
Coupling device
Inductors are sometimes used in electrical circuits where a sudden rise or fall of current is undesirable. T or F?
True, the application must be able to withstand the spikes (noise or dirty power)
What are the two most important ratings of a coil?
Inductance
Current
What is the ripple formula?
Vrms of the ripple / Vdc average x 100
When dealing with the L-Section filter, the capacitor provides good filtering with large loads While the choke is more effective with small loads. T or F?
False. Capacitors are good with small loads, and chokes are good with large loads.
What does a filter do?
Used on the output of rectifiers to produce smooth dc.
What does ‘MIG’ stand for in respect to welding?
Metal Inert Gas
Describe the basic GMAW process.
Involves feeding a wire electrode through a tube onto the surface to be welded.
The three main components of a GMAW welder are:
Step-down transformer
The rectifier
The filter
GMAW welders weld with:
DC source
What is the simplest filter filter circuit?
A capacitor filter is the simplest
You can change heat settings on a welder by using which taps on a Transformer
Primary or Secondary
Name the values of these resistors:
R1: R22
R2: 22K
R3: 2M2
R1: 0.22 ohms
R2: 22k ohms
R3: 2.2M ohms
Mica capacitors are temperature stable. T or F?
True. Mica is also a good insulator.
When a capacitor is connected to a dc supply, what occurs?
The cap acts as a short circuit as the opposite charges are attracted to each other on the plates of the capacitor. Resulting in maximum current flow in the circuit.
When testing a charged capacitor, treat it as a ______ _______.
Charged battery
Describe Lenz Law
The direction of the induced emf is such that any current resulting from it develops a flux that opposes any change in the original flux.
What is the formula for time constants dealing with Inductors?
T = L / R
If you get an OL reading with an inductor coil, what is the problem?
Its become open-circuited- several windings may be shorted together because the insulation has broken down.
A variation in the magnitude of voltage is called
_______ , and is sometimes reffered to as the the ac component of ________.
- Ripple
- Voltage
A power supply with a low percent ripple has a more constant (or cleaner) dc voltage than one with a high percent ripple. T or F?
True.
To prevent the metal from oxidizing or burning when its molten during welding, what is applied to the arc area?
An inert shielding gas is supplied to displace air containing oxygen
What does the welding machine control?
The amount of current
The rate of electrode feed
The amount of shielding gas
What is the definition of Welding?
The process of joining metal components by heating them until they become liquid, letting the metal pieces fuse together and then allowing them to cool to form a strong joint.
Seam welding machines, spot welding machines and box welding machines are resistance welders. T or F?
True
How is a choke filter connected?
An inductor coil connected in SERIES with the output of a rectifier and in series with the load.
How is a capacitor filter connected?
The capacitor is connected in parallel with the output terminals of a rectifier and in parallel with the load.
How is an L-Section Filter connected?
With the capacitor connected across the output after the choke. Reducing the possibilty of voltage spikes at the load produced by the choke. Also called a choke-input filter because the choke inputs to the capacitor.
