Hus Rupani:

Now let me show you how the students will shut down this board and at the same time, measure the voltages to ensure that the circuit is isolated. So to start with, we can see that the lamp is turned on, so the power is going to the lamp. Let’s also measure the voltage that we’re getting at the socket outlet. So I’ll set my multimeter to voltage and go to AC. And I am seeing 23 volts here. So I can see that my power circuit and my lighting circuit, both of them are getting power. So let’s start off by isolating both of those circuits. So now that we’ve turned them off here, let’s double check, we know that the lighting circuit doesn’t have voltage. Let’s double check if our power circuit is isolated as well. And we’re seeing that there is no voltage coming out of this. So we have successfully isolated our power and lighting circuit.

Now we’ll follow the shutdown procedures that are listed in both of these switch boards. Let’s start with our shutdown procedure one, and then we’ll go to the shutdown procedure two. Shutdown procedure one says turn off the main switch inverter supply, which is this one. Let’s turn that off. Next one is turn off the inverter isolator, which is this one here. So let’s turn that off. Now just to double check, let’s measure the voltage that we’re seeing at the inverter output. So we are seeing that we’ve got voltage on the inverter, which means that the rest of the part is not turned off, but we know for a fact that this whole thing is turned off.

Just to confirm, I will turn this on with the inverter isolator off and turn on my lighting circuit and see if that works. And I know that the power isn’t getting through there. I can double check with my multimeter as well on the socket outlet if I wanted to confirm the power circuit as well. Let’s go back. So that’s my first two steps. Turn off the main switch inverter supply, which I’ve turned off and I have turned off the inverter isolator. The third step is follow the shutdown procedure two in the main DC switch board, which is here.

So let’s go to the main DC switch board. First step is follow shutdown procedure one. That’s only there to reiterate that you need to do the isolation here before you get to this point. Second step, turn off inverter switch. So if I turn this inverter switch off, I am expecting to see no voltage at these points here. Let’s double check. Since now it’s all DC I’m going to change my multimeter to a voltmeter to DC range and I’m seeing about two volts, which is slowly dropping. It’s probably some sort of charge left over, but it is dropping and we can tell that it is turned off. Next step is turn off PV array switch, which is this one here. So we turn the PV array switch off.

Now since this PV array switch is off, we will hope to see no voltage on the input of the solar charge controller. Let’s double check. And we have about 0.6, 0.5 and it is dropping. So we know that there is no voltage coming from the solar panel to the solar charge controller. If I check the voltage here, I can see that I still have voltage, but I know that I don’t have any voltage here because I’ve isolated that part. Okay, the next step is turn off PV array DC isolator, which is this one. So we just checked here that there was voltage, we turned that off. Let’s double check. And now I’m seeing no voltage here.

If I double check here, I’ve still got about 28 volts, but if I check on this side, I have nothing. So we have isolated our solar panel voltage going to the solar charge controller. Next is turn off charger switch. So if I turn this charger switch off, I have basically disconnected my solar charge controller from the battery. If I measure the voltage here, I’m only getting about 1.6, but this is really because my power is not coming to the solar charge controller. However, if the charger switch was on, I would see the battery voltage here because the battery and the solar charge controller are connected there. By turning this off, I have isolated them.

Last step of our shutdown procedure is turn off battery systems isolator. So before we turn that off, let’s just measure the voltage on the terminals. So here I’m seeing 13.35 and on the battery I’m seeing 13.35 as well. Let’s turn that off and double check what we’ve got. And I’m seeing zero volts here. So we know that the battery is isolated, but let’s just double check our battery terminals. We still have 13.35 volts, so we have successfully shut down the system. Just to reconfirm that there is no current flow. We’ll use our clamp meter to measure the current at different points.

Let’s start off with our PV input to the solar charge controller. I’m seeing 0.08, so pretty much zero amps there. Output off the solar charge controller, I have nothing. I want to ensure that this battery is not supplying current to anything and I’m getting 0.07 amps as well. And just to see if our inverter is not getting power from anywhere else, I am seeing 0.07 amps there as well. So we have confirmed with our voltmeter that there are no voltages present and we have confirmed from our clamp meter that there are no currents present. The only thing we still have is the voltage across here and across the battery terminals. Because those two energy sources, realistically we can’t turn them off. They will always have some voltage showing.

Now we’ve completely shut down the board. This is how the students will go through the shutdown procedure and confirm that the board is isolated. Thanks for watching.