Fluke 1577 FE 1587-1577 Users Manual - Page 25

Understanding AC Zero Input Behavior of True RMS Meters True RMS Meters accurately measure distorted waveforms, but when the input leads are shorted together in the AC functions, the Meter displays a residual reading between 1 and 30 counts. When the test leads are open, the display readings may fluctuate due to interference. These offset readings are normal. They do not affect the Meter's ac measurement accuracy over the specified measurement ranges. Unspecified input levels are: • AC voltage: below 5% of 600 mV ac, or 30 mV ac. • AC current: below 5% of 60 mA ac, or 3 mA ac. Low-Pass Filter (Model 1587 and 1587T) The 1587 is equipped with an ac low-pass filter. When measuring ac voltage or ac frequency (B), press the blue button to activate the Low-Pass Filter function (K). The Meter continues measuring in the selected ac mode, but now the signal diverts through a filter that blocks unwanted frequencies above 800 Hz. Refer to Figure 5. The low pass filter can improve measurement performance on Insulation Multimeters Understanding AC Zero Input Behavior of True RMS Meters composite sine waves that are typically generated by inverters and variable frequency motor drives. XWWarning To avoid possible electric shock or personal injury, do not use the Low-Pass Filter function to verify the presence of hazardous voltages. Voltages greater than what is indicated may be present. First, make a voltage measurement without the filter to detect the possible presence of hazardous voltage. Then, select the filter function. Note When using the Low-Pass filter function, the Meter goes to Manual mode. Select ranges by pressing the r button. Autoranging is not available with the Low-Pass filter function. 800 Hz 100 Hz Figure 5. Low Pass Filter bav16f.eps 15