Measurement Categories - Tempo Communications MM810 Manual De Instrucciones

AC Measurement
AC measurements are usually displayed as RMS (root mean square) values. The RMS value is equal to
the value of a DC waveform, which would deliver the same power if it replaced the time-varying wave-
form. Two AC measurement methods are average-responding RMS calibrated and true RMS-reading.
The average-responding RMS calibrated method takes the average value of the input signal
The average-responding RMS calibrated method takes the average value of the input signal after full
after full wave rectification, multiplies it by 1.11, and displays the result. This method is
wave rectification, multiplies it by 1.11, and displays the result. This method is accurate if the input
accurate if the input signal is a pure sine wave.
signal is a pure sine wave.
The true RMS-reading method uses internal circuitry to read the true RMS value. This method
The true RMS-reading method uses internal circuitry to read the true RMS value. This method is accu-
rate, within the specified crest factor limitations, whether the input signal is a pure sine wave, square
is accurate, within the specified crest factor limitations, whether the input signal is a pure sine
wave, triangle wave, half wave, or signal with harmonics. The ability to read true RMS provides much
wave, square wave, triangle wave, half wave, or signal with harmonics. The ability to read true
more measurement versatility. The Greenlee DM-810A, DM-820A, DM-830A, and DML-430A are true
RMS provides much more measurement versatility. The Tempo MM810 is a true RMS meter.
RMS meters.
The Waveforms and Crest Factors table shows some typical AC signals and their RMS values.
The Waveforms and Crest Factors table shows some typical AC signals and their RMS values.
Waveforms and Crest Factors
Waveform
RMS Value
Average Value
Crest Factor*
(x)
* The crest factor is the ratio of the peak value to the RMS value; it is represented by the Greek
letter x.
AC + DC True RMS

Measurement Categories

AC + DC true RMS calculates both of the AC and DC components given by the expression
These definitions were derived from the international safety standard for insulation
coordination as it applies to measurement, control, and laboratory equipment. These
measurement categories are explained in more detail by the International Electrotechnical
when making measurements and responds accurately to the total effective RMS value regardless of the
Commission; refer to either of their publications: IEC 61010-1 or IEC 60664.
waveform. Distorted waveforms with the presence of DC components and harmonics may cause:
Measurement Category I
• Transformers, generators, and motors to overheat
Signal level. Electronic and telecommunication equipment, or parts thereof. Some examples
• Circuit breakers to trip prematurely
include transient-protected electronic circuits inside photocopiers and modems.
• Fuses to blow
Measurement Category II
• Neutrals to overheat due to the triplen harmonics present on the neutral
Local level. Appliances, portable equipment, and the circuits they are plugged into. Some
• Bus bars and electrical panels to vibrate
examples include light fixtures, televisions, and long branch circuits.
The DM-830A and DML-430A are AC + DC true RMS meters.
Measurement Category III
Distribution level. Permanently installed machines and the circuits they are hard-wired to.
10
Some examples include conveyor systems and the main circuit breaker panels of a building's
electrical system.
Measurement Category IV
Primary supply level. Overhead lines and other cable systems. Some examples include cables,
meters, transformers, and other exterior equipment owned by the power utility.
100 100
90 100
1.414
100
87
1 1.73
9
MM810A
100
64
2