AMETEK MX CTSL - Manual (Page 21)

User Manual MX-CTSL Compliance Test System
California Instruments Revision J 21
than 15 seconds in any 150 second period. This requirement imposes more demands on the power
analyzer being used than it does on the AC power source.
Steady state harmonics are those exhibited by equipment that has a constant current draw such as a
fluorescent lighting fixture. Many pieces of equipment, such as Laser printers that have a heating element
that kicks in any time a page is printed, have fluctuating power demands and may require transitory
harmonics testing.
Note that Amendment 14 does away with the distinction between stationary and transitory harmonics.
2.4.3 IEC 61000-4-7 Inter Harmonics Evaluation.
IEC61000-3-2 Edition 2.1 (2001-10) references measurement methods per IEC61000-4-7 and Edition 2.0
of this measurement standard specifies the inclusion of inter harmonics. For the assessment of harmonics,
the harmonic and inter-harmonic current levels are grouped to be the sum of squared intermediate lines
between two adjacent harmonics according to the equation below, as visualized also in the accompanying
figure. The resulting harmonic group component of order n (corresponding to the center line in the hatched
area) has the magnitude C (rms value).
In these equations, “c” is the modulus of the spectral component corresponding to an output bin of the
Fourier Transform of the data obtained from the 200 ms acquisition period , and “C” is the resulting
modulus of the harmonic which is to be compared against the limits in IEC61000-3-2 for the selected test
class.
This inter harmonics measurement is not mandatory as of this writing, as the use of equipment meeting the
previous version of IEC61000-4-7 (the older Edition 1) is permitted for a short period (until the existing
IEC61000-4-7 Edition 2 has gone through its maintenance cycle). Therefore the user has the option to
either disregard inter harmonics, or to group them into the assessment by selecting the appropriate field in
the “Test Category” settings.
It should be noted that selecting this “inter harmonics grouping” has little impact on the measurement
results for the vast majority of products. Only products with active power factor correction AND highly
fluctuating power consumption will produce inter harmonic levels that would add to the level of “C” as given
above. Most products do not produce inter harmonics, and therefore the measured harmonic currents will
be the same either way.
2.5 EN 61000-3-3 Flicker
Flicker standards are imposed to limit voltage variations caused by loads connected to the low voltage
supply network that would cause lights connected to the same circuit to flicker. A complex measurement