Title: Facilitator Help Page: Lab 10-3 -- (Do Not Publish)
Course: Basic Electrical Theory and Wiring (Sandbox) > Section: Module 10: Series Circuits

Expectations and Answers

1. The student must show their face in the video for credit.
2. The student must be wearing safety glasses covering their eyes to get credit.
3. The student must submit a legible schematic. See the example below for this lab schematic.
4. The student must have their name, date, and lab number on the schematic.
5. The wire colors must be on the schematic.
6. All components must be labeled. This includes circuit breakers, push buttons, switches, motors, fans, solenoids, resistors, etc.
7. The drawing must be wired to their schematic.
8. The circuit must work.
9. The student must correctly measure the voltage drop across the fan. Measure from V+ of the 24V power supply to the black wire of the fan (or the resistor wire where the black wire connects.)
10. The student must correctly measure the voltage drop across the solenoid. Measure from the red wire (or the resistor wire where the red wire connects) to the V- on the 24V power supply.
11. The student must correctly measure the amps across the fan. This works best to turn off the switch then clamp the Extech around the red wire of the fan. Then, zero the Extech. Lastly, turn on the switch to get the amps.
12. The student must correctly measure the amps across the solenoid. This works best when you turn off the switch and then clamp the Extech around the red wire of the solenoid. Then, zero the Extech. Lastly, turn on the switch to get the amps.
13. The student must explain why the solenoid doesn't work.
  1. A series circuit can only send a finite amount of current down the branch. The amount of current is limited to the electrical pressure or voltage of the circuit. Thus, the branch is limited to a finite amount of power. When things are wired in series, the total power cannot exceed the voltage and current of the system. In this case, there is not enough power to power both the fan and the solenoid. The student should notice that the current should be the same. Due to the Extech, the measurements may vary. The student will notice that the voltage drop across the fan is around 21V and around 3 volts through the resistor and solenoid. The solenoid needs around 12 volts to run. The solenoid can be placed first, and you would think that then the solenoid would work and not the fan. The issue here is that the solenoid works based on a buildup of a magnetic field which takes time to build. Therefore, while the solenoid is trying to build a magnetic field, the fan takes the current and starts running, so the fan will work whether it is first or last. The fact remains that there isn't enough power to run both devices. If we had 48 volts going into the circuit, we could run them both, assuming that the fan didn't burn up before the magnetic field was built up.
14. The student clearly shows lockout/tagout in their video.
15. The student clearly shows that they have verified with a multimeter that the voltage is at or near 0V.

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