AMETEK MX CTSL - Manual (Page 69)

User Manual MX-CTSL Compliance Test System
California Instruments Revision J 69
5.4 Stationary or Transitory Harmonics Test
The EN 61000-3-2:1998 standard distinguishes between two types of tests, stationary for equipment that
exhibits constant power consumption and transitory for equipment that exhibits fluctuating power
consumption patterns. While the harmonic current limits applied to each type of EUT are identical,
equipment that produces transitory harmonics is allowed to exceed the limit levels by 50 % as long as such
excessive levels last less than 10 % of the total time during any 2.5 minute period. This is equivalent to 15
seconds of the total period (2.5 minutes = 150 seconds, 10 % of 150 seconds = 15 seconds).
The user should determine the nature of the EUT based on his knowledge of the product. As a rule, the
transitory harmonics standard is easier to pass as there is some margin (up to 50 %) compared to the
stationary harmonics test. In case of doubt, it is always possible to run a stationary harmonics test on the
EUT first. If the stationary test passes, you are done; a unit that passes the stationary harmonics test will
always pass the transitory harmonics test. The reverse is not true however. If a unit fails the stationary
harmonics test, it may still pass the transitory harmonics test as long as the current harmonics do not
exceed 1.5 times the class limits and do so less than 15 seconds in any 2.5 minute period.
It should be noted that the user must ensure that the total test time applied is sufficient to cover a complete
operating cycle of the EUT. Many devices are stationary in nature but notable exceptions exists. For
example, a laser printer that periodically draws higher currents to heat the fuser may exhibit fluctuating
harmonics and may require a test time that is sufficiently long to cover such an event. The same applies to
microwave cookers and washing machines.
Note: The user is responsible for selecting the correct test method for the EUT. The CTS system does
not attempt to determine if the EUT exhibits stationary or transitory harmonic currents. If in doubt,
select the stationary test method as it is the most stringent of the two.
If you selected the EN 61000-3-2:2000 standard, evaluation of current harmonics is always done using the
transitory method so no user selection is provided. See section 2.3.3 for details on selecting the correct
test time.