Transcript LCD display
How to use the STELR multimeter Multimeter • • • • • • • • • • Features Input jacks Turning on (and off) LCD display How to measure voltage How to measure current How to measure resistance Other measurements Use of the ‘hold’ button Use of the ‘backlight’ button Features of the STELR multimeter LCD display Multimeter LCD display Hold button Multimeter LCD display Hold button Rotary switch Multimeter LCD display Hold button Rotary switch Shock-proof case Multimeter LCD display Hold button Rotary switch Shock-proof case Input jacks Multimeter LCD display Back light button Hold button Rotary switch Shock-proof case Input jacks Multimeter Please also refer to the instruction leaflet accompanying each multimeter. Multimeter Input jacks The centre jack is a common negative Input jacks The centre jack is a common negative Input jacks The right jack should be used as positive for all measurements except when measuring between 200mA and 10A Input jacks The left jack should only be used as positive for when measuring between 200mA and 10A. For example when using the wind turbine. The centre jack is a common negative Input jacks Input jacks Tuning the multimeter on Rotary switch in ‘off’ position. Multimeter Turn rotary switch to any other setting to turn on Multimeter The display will activate once the multimeter is turned on Turn rotary switch to any other setting to turn on Multimeter If the display does not activate, it means either the battery is flat or the fuse has blown. Go to http://www.stelr.org.a u/how-to-use-stelrequip/ to find out how to change the battery and the fuse. Multimeter If the display does not activate, it means either the battery is flat or the fuse has blown. Go to http://www.stelr.org.a u/how-to-use-stelrequip/ to find out how to change the battery and the fuse. The multimeter will automatically power off if unattended for over 5 minutes. To reactivate, turn to off and then to any other setting. Multimeter LCD display If the battery is low, a battery symbol will appear in the top left corner of the display. LCD display If the battery is low, a battery symbol will appear in the top left corner of the display. It is suggested that the battery be replaced as soon as the low battery symbol appears. LCD display A small number is displayed at the bottom of the screen. LCD display A small number is displayed at the bottom of the screen. The number corresponds to the rotary switch setting and indicates the maximum reading for that setting. LCD display A reading of a 1 followed by a decimal point but no zero, indicates that the multimeter is off-scale. LCD display A reading of a 1 followed by a decimal point but no zero, indicates that the multimeter is off-scale. In this case the multimeter is set to 2V, so the ‘1.’ indicates that more than 2V is being passed through. LCD display A reading of a 1 followed by a decimal point but no zero, indicates that the multimeter reading is ‘off-scale’. The rotary switch should be moved to a higher value to allow proper measurement. In this case the multimeter is set to 2V, so the ‘1.’ indicates that more than 2V is being passed through. LCD display A negative reading is indicated by the minus symbol. The this means that the current is flowing in the opposite direction. LCD display Measuring voltage There are five different DC voltage settings Measuring voltage There are two different AC voltage settings There are five different DC voltage settings Measuring voltage There are two different AC voltage settings There are five different DC voltage settings There are no STELR activities that require the use of AC. Students should never use these settings. Measuring voltage There are five different DC voltage settings When measuring voltage, always use these two sockets Measuring DC voltage 0 – 600V Measuring DC voltage 0 – 600V 0 – 200V Measuring DC voltage 0 – 600V 0 – 200V 0 – 20V Measuring DC voltage 0 – 600V 0 – 200V 0 – 20V 0 – 2V Measuring DC voltage 0 – 600V 0 – 200V 0 – 20V 0 – 2V 0 – 200mV Measuring DC voltage Always start measuring with the meter set to the highest voltage and then move the rotary switch to lower settings until the most accurate reading is achieved. Here, the three volt STELR battery pack will deliver just under 3V. The rotary switch is set to the highest value (600V) and the multimeter reads 1V. Using different DC voltage settings The rotary switch is has been moved to 200V and the multimeter now reads 2.8V. Using different DC voltage settings The rotary switch is has been moved to 20V and the multimeter now reads 2.99V. Using different DC voltage settings The rotary switch is has been moved to 2V. Since the battery is delivering more than 2V, the multimeter reads ‘1.’ Using different DC voltage settings The rotary switch is has been moved to 2V. Singe the battery is delivering more than 2V, the multimeter reads ‘1.’ This indicates an ‘offscale’ error. The rotary switch should be returned to the previous, most accurate position Using different DC voltage settings The rotary switch is has been returned to 20V and the multimeter now reads gives the most accurate reading. Using different DC voltage settings Measuring current There are five different DC current settings Measuring current 0 – 200A 0 – 2mA 0 – 20mA 0 – 200mA 0 – 10A Measuring current There are four DC current settings for measuring lower currents. When measuring current, use these two sockets for currents below 200 mA. Measuring current When 10A has been selected Use these two sockets for currents between 200 mA and 10A. Measuring current These two sockets (used for currents below 200 mA) are protected by a 200mA fuse. Measuring current These two sockets (used for currents below 200 mA) are protected by a 200mA fuse. If overladed the fuse will blow. Measuring current These two sockets (used for currents below 200 mA) are protected by a 200mA fuse. If overladed the fuse will blow. Measuring current This most commonly happens if • the multimeter is connected directly to the power supply • The multimeter is connected directly to the wind turbine with no load To prevent blowing the fuse, students should be encouraged to always begin measuring current using the 10A setting. Measuring current For detailed instructions on how to change the fuse in the STELR multimeter go to: http://www.stelr.org.au/how-to-use-stelr-equip/ Spare 200mA fuses are supplied in the STELR Renewable Energy teacher kit. Replacing the fuse Measuring resistance There are five resistance settings Measuring resistance There are five resistance settings Measuring resistance When measuring resistance, use these two sockets. 0 – 2 MΩ 0 – 200 kΩ 0 – 20 kΩ 0 – 2 kΩ 0 – 200 Ω Measuring resistance Other measurements Other measurements There are two other settings on the multimeter that can be used for testing transistors and diodes. These are not required for use as part of the STELR program, but may be of general use in other programs. Set the rotary switch to this position Diode testing Set the rotary switch to this position Connect the black lead to the COM socket. Connect the red lead to the VΩmA socket. Connect the black lead to the cathode and the red lead to the anode of the diode to obtain a reading. Diode testing Set the rotary switch to the hFE position Transistor testing Determine whether the transistor is PNP or NPN. Set the rotary switch to the hFE position Transistor testing The hold button • When using the wind turbine, a fluctuating current is measured. • This is a result of the variable wind flow from the fan. • Pressing the hold button, ‘freezes’ the reading. • Pressing the hold button a second time returns the meter to the variable measurements. • Students can be encouraged to take three readings , five or 10 seconds apart, and average them for a more accurate measurement. Using the ‘hold’ button Using the ‘hold’ button The back light button Once the button is pressed, the backlight will illuminate the LCD display. The backlight will stay on for three minutes. Using the backlight button Once the button is pressed, the backlight will illuminate the LCD display. The backlight will stay on for three minutes. It is recommended that use of the backlight button is minimised, as it tends to drain the battery quite quickly. Using the backlight button www.stelr.org.au