Presentation on theme: "Basic Electrical Measurements 1. Basic electrical measurements 2 Basic Electrical Measurements Skill 2 Unit 2: Digital Multimeters."— Presentation transcript:
Basic Electrical Measurements 1
Basic electrical measurements 2 Basic Electrical Measurements Skill 2 Unit 2: Digital Multimeters
Basic Electrical Measurements 3 Goals of this presentation: Understand how to safely operate a digital multimeter (DMM). Learn how to set a DMM to the correct function, for a given measurement. Understand how to use a DMM to perform basic measurements.
Basic Electrical Measurements 4 A first look at the Digital Multimeter Display Function Dial Probe Input Jacks Function Buttons
Basic Electrical Measurements 5 Battery access Fuse ratings: 11 amp On the back...
Basic Electrical Measurements 6 Display Its important to understand the many different symbols.
Basic Electrical Measurements 7 Display
Basic Electrical Measurements 8 Function Dial OFF AC Volts & Hertz V DC Volts V Continuity ( tone) Ohms Diodes Capacitance AC Amps A DC Amps A )))))))) Display backlight On/Off
Basic Electrical Measurements 9 Probe Jacks Common (black) Volts, Ohms, etc. ( V ) Amps
Basic Electrical Measurements 11 Safety Inspection Physical damage: Case Display Function Buttons Selector Dial Probe Jacks
Basic Electrical Measurements 12 Safety Inspection Test leads and probes Safe to 1000 volts ( max ). Check test lead resistance: Step 1:Insert leads in V/ and COM inputs Step 2:Select, touch probe tips Good leads are How do you check a single test lead? Visually check for: Shrouded connectors not damaged: no insulation pulled away from end connectors. Insulation not melted, cut, cracked, etc. Probes: Finger guards intact, tips: not loose, broken off or burned.
Basic Electrical Measurements 13 Safety Inspection Checking meter fuses on most meters: Step 1:Plug test lead in V / input. Step 2: Select Step 3:Insert probe tip into A input and read value. (should be less than 0.5 ) Is the fuse okay? What would an open fuse read? Note: This test will only confirm that a fuse is good. It will not test for a wrong sized fuse being installed.
Basic Electrical Measurements 14 Safety Features Auto Ranging Reversed Polarity Protection 1000 volts protection on leads ( higher than maximum range of AC or DC volts )
Basic Electrical Measurements 15 DMM Measurements Volts ( AC & DC ) Resistance ( Ohms ) Diodes Continuity Amps ( AC & DC ) Frequency ( Hertz )
Basic Electrical Measurements 16 DMM Measurements AC Volts
Basic Electrical Measurements 17 DMM Measurements DC Volts V
Basic Electrical Measurements 18 DMM Measurements Continuity Tone can be heard when resistance is typically less than 50 ( 250 max ). ))))))))
Basic Electrical Measurements 19 DMM Measurements Resistance Maximum 40 M Six ranges (auto or manual)
Basic Electrical Measurements 20 DMM Measurements AC Amps A 10 Amps maximum Protected by internal fuse Change positive lead to A input LEAd is displayed whenever switching to or from amps mode, as a reminder to change the positive lead.
Basic Electrical Measurements 21 DMM Measurements DC Amps A 10 Amps maximum Protected by internal fuse Change positive lead to A input LEAd is displayed whenever switching to or from amps mode, as a reminder to change the positive lead.
Basic Electrical Measurements 22 Common DMM / User Hazards Voltage contact while in continuity or resistance Protection: Overload protection in ohms up to the meters volt rating. Measuring voltage with test leads in current jacks Protection: High energy fuses rated to the meters voltage rating. Shock from accidental contact with live components Protection: Test Leads double insulated, recessed / shrouded, finger guards. Replace when damaged. Using meter or tester above rated voltage Protection: Good karma !
Basic Electrical Measurements 23 Summary What we learned: Functions of the DMM Safety inspection How to check for good test leads How to test for open fuses Function of overload protection Why amperage inputs need fuses How to take measurements Common user hazards
Basic Electrical Measurements 24 Ohms Law
OHMS LAW POWER I I I I I I I R R R R R R RE E E E E E E P P P P P P P VOLTS OHMS AMPS
OHMS LAW R E P I EI Primary Use: DC Circuits Primary Use: AC Circuits - KEEPING IT SIMPLE -
Basic Electrical Measurements 27 Review Safety check the meter and leads prior to use Place the Test Leads in correct input Amps input is low impedance 10 A max Safety- fused use correct fuse only Select the correct function for the reading you want Min / Max and Hold functions can be useful