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Electronics Period 4 SAIT > Welders & Filters > Flashcards

Welders & Filters Flashcards

1
Q

What are the most important ratings when replacing resistors

A

Power
Resistance
Tolerance
The maximum voltage

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2
Q

What is the fourth band of a resistor represent?

A

Tolerance

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3
Q

Three characteristics that affect the capacitance of the capacitor:

A

Surface area of the plates
Distance between the plates
Dielectric constant between the plates

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4
Q

Electrolytic capacitors are polarity sensitive. T or F?

A

True

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5
Q

A capacitor can be used as what sort of device to block dc and pass ac if placed in series?

A

Coupling device

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6
Q

Inductors are sometimes used in electrical circuits where a sudden rise or fall of current is undesirable. T or F?

A

True, the application must be able to withstand the spikes (noise or dirty power)

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7
Q

What are the two most important ratings of a coil?

A

Inductance
Current

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8
Q

What is the ripple formula?

A

Vrms of the ripple / Vdc average x 100

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9
Q

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?

A

False. Capacitors are good with small loads, and chokes are good with large loads.

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10
Q

What does a filter do?

A

Used on the output of rectifiers to produce smooth dc.

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11
Q

What does ‘MIG’ stand for in respect to welding?

A

Metal Inert Gas

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12
Q

Describe the basic GMAW process.

A

Involves feeding a wire electrode through a tube onto the surface to be welded.

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13
Q

The three main components of a GMAW welder are:

A

Step-down transformer
The rectifier
The filter

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14
Q

GMAW welders weld with:

A

DC source

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15
Q

What is the simplest filter filter circuit?

A

A capacitor filter is the simplest

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16
Q

You can change heat settings on a welder by using which taps on a Transformer

A

Primary or Secondary

17
Q

Name the values of these resistors:

R1: R22
R2: 22K
R3: 2M2

A

R1: 0.22 ohms
R2: 22k ohms
R3: 2.2M ohms

18
Q

Mica capacitors are temperature stable. T or F?

A

True. Mica is also a good insulator.

19
Q

When a capacitor is connected to a dc supply, what occurs?

A

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.

20
Q

When testing a charged capacitor, treat it as a ______ _______.

A

Charged battery

21
Q

Describe Lenz Law

A

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.

22
Q

What is the formula for time constants dealing with Inductors?

A

T = L / R

23
Q

If you get an OL reading with an inductor coil, what is the problem?

A

Its become open-circuited- several windings may be shorted together because the insulation has broken down.

24
Q

A variation in the magnitude of voltage is called

_______ , and is sometimes reffered to as the the ac component of ________.

A
  1. Ripple
  2. Voltage
25
Q

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?

A

True.

26
Q

To prevent the metal from oxidizing or burning when its molten during welding, what is applied to the arc area?

A

An inert shielding gas is supplied to displace air containing oxygen

27
Q

What does the welding machine control?

A

The amount of current
The rate of electrode feed
The amount of shielding gas

28
Q

What is the definition of Welding?

A

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.

29
Q

Seam welding machines, spot welding machines and box welding machines are resistance welders. T or F?

A

True

30
Q

How is a choke filter connected?

A

An inductor coil connected in SERIES with the output of a rectifier and in series with the load.

31
Q

How is a capacitor filter connected?

A

The capacitor is connected in parallel with the output terminals of a rectifier and in parallel with the load.

32
Q

How is an L-Section Filter connected?

A

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.

Electronics Period 4 SAIT (8 decks)

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