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Well, the explanation we give in Unit 5 is already pretty brief! As an appliance repair tech, you don’t have to have a deep understanding of how transformers do what they do, and you’ll be revisiting some of these concepts as you go along in the course. But I appreciate that you are trying to understand the material the best you can right now. Let’s see if I can help with that…
First: “what” they do. Here’s the main point (from the lesson): “Transformers get their name from the fact that they “transform” one voltage or current level into another. They are capable of either increasing or decreasing the voltage and current levels of their supply, without modifying its frequency, or the amount of electrical power being transferred from one winding to another via a magnetic circuit.”
Do you have any questions about that?
As for “how”, it’s good to understand this, at least in a general sense, because this is also basically how motors work (with windings and magnetic fields).
Here’s how we explain it in the lesson:
A single phase voltage transformer basically consists of two electrical coils of wire, one called the “Primary Winding” and another called the “Secondary Winding”. Normally, the “primary” side of the transformer is the side that takes power, and the “secondary” is the side that delivers power. In a single-phase voltage transformer, the primary is usually the side with the higher voltage.
These two coils are not in electrical contact with each other but are instead both wrapped around a common closed magnetic iron circuit called the “core”. This soft iron core is not solid but made up of individual laminations connected together to help reduce the core’s losses.
The two coil windings are magnetically linked through the common core allowing electrical power to be transferred from one coil to the other. When an electric current is passed through the primary winding, a magnetic field is developed which induces a voltage into the secondary winding as shown.
(see the figure in the unit)
Do you follow that explanation? You’ll be revisiting these concepts in various ways as you go along, so don’t feel you have to completely understand it yet.
You’re welcome! Glad to help.
Correct!
Yep! So your meter reading would reflect that.
Exactly!
Right! So if you have a circuit with multiple loads, you can do that with one of them. If your hand has to travel through another load in order to reach either L1 or N, then that load is in series with the one that you have become. That’s one way to check if loads are in series. Loads that you do not have to go through, but that are still connected to the same power supply, would be in parallel to you.
Does that help?
Correct – so would any current be flowing?
Sure – but I was hoping you would give me the answer – the name of the situation I am talking about – so I can make sure you got it.
It’s a good idea to take the time to get these circuit configurations straight in your mind.
The videos at the end of Unit 4 are good to review for this.
Also, do you understand the “Zen trick” we teach in the second video in Unit 5?
When you figure out the answer to Question 3, I think you’ll see what this answer is.
These light bulbs are in series.
In a circuit, you must have a complete path to and from the power supply for current to flow. (If we’re talking about a 120vac circuit, then we need an unbroken path from L1 to N.)
Since the bulbs are in series, there is no alternate path for current to flow. The electrons have to be able to go through both of them in order to have current flow.
What happens to the circuit when a light bulb blows?
Voltage drop is directly proportional to the resistance of a load. In other words, higher resistance equals higher voltage drop.
If you had two or more loads in series, the only way their voltage drop would be identical is if they had the exact same resistance.
Hi Ladarius,
Thanks for posting your questions in the Forums!
It is not a small difference for that switch to be closed – it affects the circuit quite a bit.
What the branch does to the circuit when the switch is closed is discussed in the 3rd video in Unit 5. It is a particular circuit design to control loads (either give them power or divert it).
Do you know what I’m referring to?
Note that the questions don’t tell you the voltage drop – they are asking you to determine the voltage drop. They tell you the lines of voltage that are applied to either side of the load.
Remember voltage drop is created by current flowing through a load.
And current will only flow in a circuit where there is a difference in voltage applied to either end.
Ah! You are looking at the wrong light on the schematic. The “surf ind light” just goes on when any surface element is turned on. The hot surface indicator lights are different. There are 4 of them, and they are switched by a thermostat and come on if the glass temp is >150 deg.
I’m not sure how you got the other questions correct on these quizzes. You should be looking at the LF “hot ind light” (there are 4 of those lights)
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