Susan Brown

[Susan Brown]

Yes, that’s what it is good for!

[Susan Brown]

Current depends on the resistance in a circuit.

The only generalization you can make about parallel circuits is that they each have the same source voltage, since each branch is tied to Line and N (or L1 and L2 if a 240 circuit).

The current going through each parallel branch will depend on the resistance of the load(s) in the branch. Only if each branch had an identical load would the current would be the same.

Does that help?

[Susan Brown]

You got it! The key to this question is recognizing the shunt. Everything falls into place after that.

[Susan Brown]

When the detector switch is closed, they will all go through that circuit, since it has no load.

By definition, (which we gave in Unit 1 and also talked about in more detail in Unit 5) all the current will go through a shunt, if one is available. It’s how loads are controlled in a lot of circuit configurations – switches sometimes close to create a shunt that bypasses a load so that it won’t do any work.

An unintended shunt (that happens by accident) is a “short”.

[Susan Brown]

Hi Shawn,

A lot of people call those “finger drivers”. We got ours at our local hardware store, but here’s an example at Amazon:

https://amzn.to/2ZsUz3v

[Susan Brown]

Hi Bill,

I moved your question to a new topic, since it didn’t really have to do with that other thread.

See the video in this forum topic – it should help you!
https://my.mastersamuraitech.com/appliance-repair-course-support/student-forums/topic/calculating-equivalent-resistance/

[Susan Brown]

There’s a big difference between a path with resistance (a load) in it and a path with none. A shunt is not like a parallel circuit, because ALL of the electrons will choose that path over one with a load in it.

Keeping that in mind, take another look at the circuits and see what you think.

[Susan Brown]

When electrons have two paths available to them, and one has a load and the other does not, what happens? (This is a particular circumstance that we address in Unit 5.)

[Susan Brown]

Forget about main for the moment.

If you are the igniter or the booster, don’t you have more than one option to get to N? Remember, electrons don’t “see” bends or connections in the wires.

[Susan Brown]

Hi Duane,

Thanks for posting a question! I did move it to the Basic Electricity forum, and gave it a new title.

Short answer to your question is no – there will never be a partial voltage drop across a load if it is the only load in the circuit.

It’s an observable law – “Kirchoff’s Law” – the sum of the voltage drops in a series circuit shall always, everywhere, and forever add up to the supply voltage. It’s related to the conservation of energy, but there’s no need to try to understand it deeper than that. We just have to accept it!

In the video you referred to, if we changed the lightbulb to something with a different resistance, that would change the current flow in the circuit.

I = E/R

The voltage is determined by the power supply, and the resistance in the circuit is determined by the loads that are in the circuit. The current will be whatever it takes to drop all the voltage across the load(s) in the circuit.

Does all of that help?

[Susan Brown]

By the way, here’s a great webinar recording at Appliantology that would be helpful, if you haven’t seen it yet:

https://appliantology.org/topic/72423-voltage-voltage-drop-loads-switches-jumpers-cheaters/

Also, we’ve got some recent videos at our YouTube channel that show voltage measurements on various jobs.

https://www.youtube.com/user/SamuraiRepairman/videos

[Susan Brown]

Hi Nate,

They don’t give us the strip chart for this washer or enough information to know exactly what that “full – empty” area is doing, with the two switches and the wire between them. All we can do is go by what they say in the text, which is when the tub is empty, the water level switch is as drawn, which energizes the circuits in the bottom half of the schematic that have closed contacts. When the tub is full, the switch flips up and energizes the top circuits.

When the motors and agitate solenoid are energized, switch 8 is open. No electrons will flow through that circuit.

Does that help?

[Susan Brown]

Hi Nate,

A Watt is by definition 1 Joule per second. The time increment is part of what a Watt is.

You could say that 1 BTUH (or, BTU/hr) is equal to 0.29307107 Joules/second if that helps you picture it.

There’s no need to make the time increment equivalent, since we are only ever going to use the units BTUH or Watts. We don’t need to know Joules/hour or BTU/second, for example.

When you say a car is going 55 mph that doesn’t imply that the car is going to drive for an hour. It just says that IF the car drove at that rate for an hour, it would traverse 55 miles.

Joules and BTUs are different from each other, just like kilometers are different from miles. We could convert 55 miles/hour to whatever number km/minute, and that car would be still driving at the same rate of speed.

Does that help?

[Susan Brown]

Might have been! Of course, there are sharp edges on other brands as well. It’s definitely something to watch out for.

[Susan Brown]

Yes, that’s a joke 🙂
Some of Frigidaire’s models over the years have been frustrating to work on. I remember Samurai once saying he thought that Frigidaire engineers hated appliance techs, since they made their machines so hard to work on, with lots of sharp metal edges, etc.

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