Using a Digital Multimeter to Check Amperage | ACDelco TechConnect

[Music] hello I'm Peter Robert from ACDelco today David is going to demonstrate amperage testing using a digital multimeter hello my name is David Wells and today I'm going to speak to you about measuring amperage using a digital multimeter or DMM before we get into actually using the tool to measure amperage we should first talk about what amperage is amperage is simply a measurement of strength of electrical current through a circuit current as we know is the flow of electricity from one point to another using conventional theory it would flow from positive to negative using the DMM we can then measure the strength of that current and know how much electricity is flowing through a circuit before we actually measure current on the circuit let's talk a little bit about the tool we use to do that for our purposes we'll be using a fluke 87 digital multimeter your meter may differ slightly but the basic operation should be the same the important points that you want to understand about the meter are the input jacks here in here and the rotary dial as far as the input jacks are concerned the main two that you'll be using are the amps terminal and the milliamp and micro amp terminal you will also be using the common port for our to complete our path the rotary dial the positions you'll be using are here the milliamp amps signing and the micro amps setting before we use the meter we should first check the fuses to do this we insert our red lead into either the amp terminal or the micro amp terminal and then turn the meter on to any position other than the amp setting if you hear a beep and see the word lead at the top display you know that the fuse is working properly to test the milliamp fuse remove the lead over to that position and do the same thing that beep tells us that our fuses are good if we did not hear a beep then our fuse will be blown and we would need to service the meter before using it let's talk about the fuses the two fuses are a 10 amp fuse to protect the amp terminal and a 400 milli amp fuse to protect the milliamp micro amp terminal if you exceed those ratings the fuse will blow and the meter will not work okay let's take a look at how we're going to measure amperage on a simple circuit you can see on our project board here we have a simple circuit set up to flow DC current or direct current through our light bulb we have our 13 volt power supply here it flows through this red wire here through our fuse to our switch over to this wire to the input side of the bulb through the bulb and then to the ground so if I turn the switch on you can see we have a working circuit here now we want to understand how to measure amperage through this circuit first we'll shut our circuit off power it down next we need to set up our digital multimeter well do that by inserting the leads into the proper terminals you want to always start by inserting the red lead into the amp terminal if we're measuring a lower current circuit we can move the lead over to the milliamp scale however it's important to always start at the amp scale that way if the current exceeds the 400 milli amp fuse rating we don't blow the fuse next we'll take our black lead and insert it into the common or ground terminal next we need to turn our meter on since we're going to start at our high level we want to turn our rotary knob to the milliamp amp setting that will read our higher scale the next thing you want to do is adjust these meter to read either AC or alternating current or DC direct current since we're working on a direct current circuit here we'll need to switch our meter from AC to DC you can see on the display here we're currently set for AC by pushing the yellow function button that cycles our meter to the DC scale we're now ready to measure amperage remember during amperage is measurement of the strength of electricity flowing through a circuit in order to do that we need to make the digital multimeter part of the circuit to do this we need to break the electrical circuit and insert the meter in line to do that we start off by powering down our circuit which we already are we next need to create an open within our circuit I'll do that by disconnecting it here remember amperage is the same throughout the entire circuit so it doesn't matter where you disconnect the circuit your reading will be the same throughout your next step will be to insert the red lead to the most positive side of the circuit in other words using conventional Theory electricity will flow from our power point down through the switch to the bulb into the ground therefore power is coming from this direction we want our red lead on this side of our break next we'll insert our black lead into the wiring to complete the circuit now with the meter connected when I turn the switch on electricity should flow from our power point through this red lead through the fuse through the switch then through the red lead of our meter into our meter out our black lead around through to this green wire and then onto the bulb and ultimately to ground at this point we should read amperes as you can see on our display we are reading 0.236 amps of current through this circuit or 236 milliamps since we are below our 400 milliamp threshold if we want to find a resolution we can simply move our lead over to the milliamp microamp input and read a higher resolution on our meter and indeed we can see we are now reading 230 point 6 milliamps for amperage readings below 1 milliamp you can use the micro amp setting on the meter simply turn the knob to the micro amp setting you will probably also need to change your function from AC back to DC and then you can read microamps as you can see where our meter is displaying Oh L or out of limits which means we're currently reading more than one milliamp because of that we know that we need to switch our dial back to milliamps change our function back to DC to properly read this circuit hopefully this demonstration has helped to show you the proper way to measure amperage in a circuit thanks David remember when testing amperage the meter is hooked up in series and the circuit should be operating if the circuit does not operate your meter might not be hooked up correctly thanks for watching

Channel: GM Genuine Parts & ACDelco

Views: 849,147

Keywords: check amperage, digital multimeter, acdelco techconnect

Id: x2NLYydxbo4

Length: 7min 39sec (459 seconds)

Published: Thu Sep 07 2017