User Manual – Rev J
CS Series
California Instruments
80
Figure 4-8: Selecting Waveforms for Single Phase or All Phases
Different waveforms may be selected for each phase. The number of custom waveforms from
which to select remains 50 but each phase can be assigned a different custom or standard
waveform. The specific output phase for which the wave shape is programmed is selected with
the
Phase
key on the front panel. To select the same wave shape for all three phases in a
three-phase configuration, press the
Phase
key until all phase enunciators (øA, øB and øC) are
lit. Waveform selections made in this mode will apply to all three phases.
4.4.3
Creating Custom Waveforms
The CS controller supports up to 50 user defined waveforms in addition to the 3 standard
waveforms. Custom waveforms cannot be created from the front panel of the CS Series.
Rather, they have to be downloaded through the IEEE-488, RS232C, LAN or USB interface.
Each waveform is defined by 1024 data points. Each data point can range between –1 and +1
(floating point number). See CS Series programming Manual (P/N 7004-988) for details on
downloading waveforms.
Once downloaded, waveforms remain in non-volatile memory and will be visible in the
WAVEFORMS menu for selection. The user can assign a 12-character name to each custom
waveform. Avoid using any of the standard waveform names (SINE, SQUARE or CLIPPED) as
these names will not be accepted. Also, names cannot begin with a number.
Waveforms may be deleted using the IEEE-488, RS232C, LAN or USB interface as well.
Custom waveforms cannot be deleted from the front panel however to avoid accidental erasure.
4.4.4
RMS Amplitude Restrictions
The output of a sine wave may be programmed to the full rms value of the current range . If the
The maximum programmable rms current is 14.8 Amps. If a custom waveform is used however,
the maximum programmable rms current may be less than the maximum range value. The
current limit is based on the use of a sine wave with a 1.414 crest factor. A 14.8 Arms sine
wave has a 20.93 Volt peak voltage. If the user selects a custom waveform with a crest factor
that is higher than 1.414, the peak current would exceed this maximum if the rms current were to
be programmed at 14.8 Arms.
The CS Series power source automatically limits the maximum allowable programmed rms
current of any custom waveform by calculating the crest factor of the selected waveform and
controlling the rms limit accordingly. Thus, each custom waveform may have a different
maximum rms value. The controller will prevent the user from programming the rms current
above this limit. If a value is entered in the PROGRAM menu above this value, a “Current peak
error” message is generated.
Figure 4-9: Waveform Crest Factor Affects Max. RMS Current.
