Amprobe 37XR-A Professional-Digital-Multimeter - Manual (Page 14)

7
Additional Features
Input Test Lead Warning
The meter emits a continuous tone when a test lead is placed in the mA or 10A
input jack and the Function/Range Switch is not set to a correct current position. (If
the meter is connected to a voltage source with leads connected for current, very
high current could result). All current ranges are protected by fast acting fuses.
True-rms Measurements
For ac measurements most DMMs average the ac input signal and display the
result as an estimated rms value. This average-responding method is accurate for
sinusoidal waveforms, but can be very inaccurate for distorted waveforms. To
ensure the most accurate measurements, always use a true-rms DMM when
measuring ac voltage or ac current on circuits for the following kinds of
applications:
x
Power Supplies - diodes
x Controllers
x Power Limiting - SCR or Triac
x Starting - motors
x
Florescent Lighting - ballasts
x
Speed Control - motors
x
Pulsed Signals
x Any non-sinusoidal ac waveform
MIN MAX AVG Measurements
The MIN MAX AVG function reads and updates the display to show the maximum
or minimum value measured after you press the MIN MAX AVG button.
Pressing the MIN MAX AVG button for less than 1 second will put the meter into a
mode of displaying the maximum, minimum, average, or actual readings. Each time
the button is pressed, the meter will cycle to the next display mode as shown in the
table below. Press the MIN MAX AVG button for more than 2 seconds to disable
this feature.
Button Display Value Displayed
< 1 second REC MAX Maximum value after feature activated
REC MIN Minimum value after feature activated
< 1 second REC AVG Average value after feature is activated
< 1 second REC Actual reading, min max being recorded.
> 2 seconds Exit MIN MAX AVG Normal measurement, actual reading
Peak Hold Measurements
Note: The PEAK function calibrates itself to meet the specifications.
Peak Hold records and stores the positive and negative peak values that occur while
measuring ac current or ac voltage. To enable the Peak Hold feature press the PEAK
button for more than 2 seconds. The display will show CAL to indicate the
calibration cycle is in process. After the CAL indication clears, press the PEAK
button again to display the maximum (P+) value for the ac voltage or ac current
being measured. The display will toggle between the P+ and P- readings each time
the PEAK button is pressed. Press the PEAK button for more than 1 second to exit
the PEAK function.