Welders & Filters

Question 1

What are the two types of resistor groups?

Answer 1

Fixed Resistors
Variable Resistors

Question 2

What are the two most important ratings of a resistor?

Answer 2

Resistance and Power

Question 3

What are the three most important ratings of a capacitor?

Answer 3

Capacitance
Voltage
Tolerance

Question 4

What are the two most important ratings of a coil?

Answer 4

Inductance and Current

Question 5

In a DC cct, what is the formula for how much time it takes for a Capacitor to charge?

Answer 5

T = R x C (times 5 time constants)

Question 6

Define Resistance

Answer 6

The oppositions to current flow.

Question 7

What else might a variable resistor be called?

Answer 7

Potentiometer
Trimmer
Rheostat

Question 8

What is a wiper?

Answer 8

The middle lead of the three-lead potentiometer

Question 9

What are the physical properties of a Capacitor?

Answer 9

A capacitor is two conductive plates separated by a dielectric layer.

Question 10

Name the six most common dielectric materials used in a capacitor.

Answer 10

Paper
Plastic Film
Mica
Ceramic
Electrolytic
Tantalum

Question 11

Define Inductance

Answer 11

Inductance is the opposition to a change in current.

Question 12

What are three devices that have the property of inductance.

Answer 12

Inductors
Coils
Chokes

Question 13

In a DC cct, what is the formula for the rate of change using an Inductor?

Answer 13

T = L / R

Question 14

What is a Choke Coil?

Answer 14

An inductor that suppresses a sudden rise or decrease in current

Question 15

What does it mean if you get an OL reading while testing a coil?

Answer 15

The coil is open circuited and needs to be replaced

Question 16

Define the term Ripple.

Answer 16

Ripple is the variation in magnitude of voltage

Question 17

What does a filter do?

Answer 17

A filter produces smooth DC voltage.

Question 18

A power supply with a low percent ripple has a smoother DC waveform or a bumpy DC waveform?

Answer 18

Smoother and more constant (or cleaner) DC Voltage

Question 19

What is the formula to calculate %Ripple?

Answer 19

V rms / VDC ave

Question 20

How should a capacitor be connected to the rectifier filter output?

Answer 20

I’m parallel with the output terminals of the rectifier.

Question 21

How should an inductor be connected to the rectifier to filter output?

Answer 21

In series with the output of the rectifier

Question 22

Name two factors that affect the amount of ripple the load sees in a capacitor filtered cct?

Answer 22

1. Amount of capacitance (more cap = higher average voltage)
2. The resistance or impedance of load

Question 23

What are two factors that determine how well the choke filters the output?

Answer 23

1. Inductance of the choke
2. Amount of current

Question 24

What type of load is best suited for a capacitor filter?

Answer 24

Capacitor filters are good for small, constant loads.

The greater the load, the faster the capacitor discharges, and the greater amount of ripple.

Question 25

If there is no load connected, what will the voltage at the capacitor filter be?

Answer 25

V Peak

Question 26

What type of load is best suited for a choke filter?

Answer 26

Choke filters are good for large constant loads (less resistance).

This creates a greater variation from zero to peak value of current. Large loads try to create a larger variation in current than a small one.

Question 27

What type of loads are best suited for an L-Section Filter?

Answer 27

Varying loads

Question 28

Why should an L-Section filter be connected as a choke input?

Answer 28

To reduce the possibility of voltage spikes at the load produced by the choke.

Question 29

What are the three main electrical sections of a welding machine?

Answer 29

Transformer
Rectifier
Filter

Question 30

In a welder, what is the purpose of a varistor or surge suppresser?

Answer 30

The varistor is connected between the positive and negative terminals of the bridge and is used to protect the diodes from high voltage spikes.