KEPCO EL Series Electronic Load Operator Manual P/N 243-1295 Firmware Version 3.22 through 3.41 - Manual (Page 54)

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SERIES EL 062011
special situation, damping adjustments are best made using a test set up as shown in Figure 3-
5.
Figure 3-6 shows various waveforms that may appear at the current monitor output (I-Load)
when the load is connected to a high current source and the current drawn from the source
changes rapidly following a square wave (or pulse) source connected to the E-Load input. Fig-
ure 3-6 shows the effects of changing both the System Damping and the Mode Damping. The
exact waveforms that will be seen are highly dependent on the nature of the source, the inter-
connecting cables and the various damping setting.
FIGURE 3-5. DAMPING MEASUREMENT SETUP
Damping adjustments are made using the SCPI Commands found in Appendix B via either the
RS 232 or USB remote interface.
• System Damping. Use SYST:DAMP command (see PAR. B.81).
• Mode Damping. Use SYST:PFM:DAMP (see PAR. B.88).
When modifying the damping settings, a good approach is to start with SYSTem:DAMPing 5
(the factory default) and adjust the Mode Damping from 3 to 2 or 4 while observing the results
on an oscilloscope connected to the I-MON terminals (Figure 3-5). Once the impact of the Mode
Damping adjustments are understood, a change in System Damping may be warranted.
A test plan should anticipate potential conditions that may cause an under-damped response to
transitions. Some basic steps taken at setup may help minimize problems:
• Where possible, use short cables between the source (UUT) and the load.
• Maximize the size of the cables to minimize both resistance and inductance.