Susan Brown

[Susan Brown]

Hi Sajjad,

Do you know how timer contacts work? They open or close a circuit for one or more loads. So, they are either supplying L1, L2, or Neutral to a load, depending on the configuration.

[Susan Brown]

Hi Ronny,

I think you’re just mixing up the math

He’s telling you that the resistance of R1 is two times that of R2.

So, whatever R2’s resistance is, R1 will be two times that. If R2 is 10, R1 would be 20. If R2 is 50, R1 would be 100.

Since we know that R1 + R2 has to equal the voltage supply (120), then there is only one pair of values that will meet both criteria:

R1 = 2 x R2

AND

R1 + R2 = 120.

R1 = 80
R2 = 40

[R1 + (2 x R2) = 120 is not a correct way to rewrite the equation. You could substitute (2 x R2) for R1 and write (2 x R2) + R2 = 120. This then equals 3 x R2 = 120, which gives us R2 = 40.]

Does that help?

[Susan Brown]

Thanks for the head’s up!

Would you please tell me which course, module and unit that appeared in so I can fix that link? Thank you!

[Susan Brown]

Hi Rodney,

1. you are close! remember that an electrical circuit has to end up where it started. Your need to select the answer that adds “module” at the end.

2. “What current carriers are present in a gas flame with a voltage difference across it?”

When you have a flame, you’ll have both electrons and ions. We show that in a couple of places in the video.

[Susan Brown]

It does take some thinking and working in order to figure this stuff out!

Think of parallel circuits as individual series circuits that are tied to the same power supply.

When we are talking about parallel circuits, we often refer to different “branches”. Each branch is actually a little series circuit.

So, each individual series circuit will follow the rules of series circuits. However, when there are two or more circuits (or branches) in parallel, the total current to/from the power supply will be the combination of the current flow in each branch.

Look at the figure below. Each branch (B, C, D) is an individual series circuit. The resistance of the load in each circuit will determine the current in that circuit.

If you had more than one load in any of the branches, then the total resistance in that branch would determine the current flow in that branch.

In this figure, if each load is identical, then the current in B, C, and D would be the same.

The sum of the currents in B, C, and D would equal the current flow found at points A. So, A = B+C+D

This is only true for current.
Does that help?

[Susan Brown]

Hi Michael,

There were 3 correct answers (we asked you to select all that apply)
LoZ setting on your DMM
Wiggy or solenoid voltage tester
Any low input impedance meter that measures AC voltage

You had only answered wiggy and solenoid tester

[Susan Brown]

You are correct! I reset you.

[Susan Brown]

Hi Ronny,

You’ll learn a lot more about series and parallel circuits in the next two units.

The current is the same throughout a series circuit.

In parallel circuits, what happens in one does not affect the others.

Current is determined by the voltage supplied and the total resistance in the circuit. Those two items are not affected by something happening in a circuit that is parallel to it.

See the last two videos in Unit 4!

Let us know if you have any followup questions.

[Susan Brown]

Hi Ronny,

Answers will vary slightly depending on how you round the numbers.

There is no practical difference between 1350 and 1352 watts from our (appliance techs) point of view.

[Susan Brown]

Hi Ronny,

Good question!

In our opinion, appliance repair is definitely doable for someone with some physical limitations. We see hundreds of appliance techs at the conferences that we go to, and many of them are not in optimal shape!

There’s very little standing around. You’re on the move, doing several calls a day. We train you how to do as much troubleshooting as possible from the control board, which minimizes the physical work.

You do have to get on the floor at times, and we strongly recommend wearing knee pads to protect your knees.

The most important physical ability is manual dexterity and a little bit of arm strength, since you use a lot of tools to do measurements, machine tear-downs and parts replacements.

You need to be able to do things like pull appliances toward you, and occasionally tip them on their front or side, then put them back into place.

The occasional job that requires heavy lifting (stacked laundry, wall ovens), you can either pay someone to help you or use specialty equipment for this purpose. These are costs that you pass along to the customer. (These types of jobs you might avoid when starting out, until you are prepared.)

You may find that doing appliance repair will help you get into a little better shape, since you’ll be moving around more than with the truck driving.

Hope that helps!

[Susan Brown]

You are correct!

Sorry for the delay in replying. We had meetings all morning.

The only “wrong” thing is that the Midterm is in Module 4, so I’ll move this conversation to that Forum.

[Susan Brown]

Good question! And you’ll learn more about this as you go along in the Module.

Here’s a short description for now:

Electrons respond to voltage.

We get current (the stream of moving electrons) when there is a difference in charge (voltage). As you said, they’ll always move toward the more positive charge.

With AC current, the voltage polarity at the power supply alternates, so that at one moment it is positive, then next it is negative, etc. This causes the electrons to go back and forth in response to the changes.

Does that help?

[Susan Brown]

Hi Robert,

It looks like Danfoss made some updates to their data since the time we made those videos.

[Susan Brown]

That’s definitely on the right track – it depends what exact number you mean for the one that drops “less”, and which load it is. You can email the answers to me so that I can give you better feedback.

[Susan Brown]

Here’s the answer:

Because the two compressor windings are in parallel, you take the equivalent resistance of those first, then calculate equivalent resistance again using that and the resistance of the fan.

Although, since you know that the equivalent resistance will be something less than the smallest resistance, you can also figure out the answer without carrying out all the calculations.

Let me know about the reset…

[Author]

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