KEPCO EL Series Electronic Load Operator Manual P/N 243-1295 Firmware Version 4.00 to 4.xx - Manual (Page 59)

SERIES EL 071414
3-23
• When using batteries, ensure they are fully charged when possible. Many styles of bat-
teries (especially lead-acid batteries) have a tendency to oscillate when excited by fast
rise-time transients. The sudden change in current causes the battery plates to warp
slightly, thus changing capacitance which interacts with the inductance of the cables.
3.14.3 DAMPING PROCEDURE USING FRONT PANEL CONTROLS
The following procedure provides the details of how to use the front panel to accomplish System
and Mode (PFM) damping directly from the front panel. Before proceeding, refer to PAR. 3.14,
3.14.1 and 3.14.2 for the setup and a full understanding of successful damping.
1. With the load disengaged (LOAD pushbutton indicator steady green) press the LOAD push-
button to engage the load (LOAD pushbutton indicator goes from green to amber).
2. Push and hold for CONTROL knob for three seconds, until the LOAD pushbutton indicator
starts blinking alternately green and amber, then release CONTROL knob.
3. Rotate CONTROL knob to select OFF mode (CI, CR, CV and CP indicators are all off), then
tap the LOAD pushbutton. The LOAD pushbutton indicator blinks alternately green and off.
4. Rotate CONTROL knob until (DAMP) is shown in AMPS display, VOLTS display
shows the System damping value and KW display shows the Model (PFM) damping value.
5. To change damping values, tap CONTROL knob. VOLTS display shows (SYST)
and KW display shows a blinking digit representing the System damping value.
6. Rotate CONTROL knob to change system damping value, then tap CONTROL knob to
accept. VOLTS display shows (PFM) and the KW display shows a blinking digit
representing the Mode (PFM) damping value.
7. Rotate CONTROL knob to change PFM damping value, then tap CONTROL knob to accept.
AMPS display shows (RAMP).
8. Tap the LOAD pushbutton to exit the menu (LOAD pushbutton changes to steady green) and
returns to OFF mode.
3.15 PROGRAMMING TIME REQUIRED TO CHANGE STATE (RAMPS)
The EL Load allows the user to ease the transition from one state to another by using the front
panel RAMP menu to set the time for three ramps:
POS: Time (from 0 to 2 seconds) required to change to a more positive state.
NEG: Time (from 0 to 2 seconds) required to change to a more negative state.
INPT: Time (from 0 to 2 seconds) to reach operating mode setpoint after engaging the load.
Ramps work in all modes except power. The three ramps each consist of up to 4000 evenly
spaced steps of 4.5 microseconds to 2.50 milliseconds to achieve the ramp time programmed
(maximum ramp time is 2 seconds). The ramp will either step from one level to the other in 4.5
microsecond steps (the minimum step time) or will execute approximately 4000 steps within a
time required to meet the ramp duration. For example, a ramp of 1 millisecond consists of 222
steps (4.5 microseconds per step). A ramp of 20 milliseconds consists of 4000 steps (25 micro-
seconds per step). A ramp of 2 seconds (maximum) consists of 4000 steps (0.5 milliseconds per
step).